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MPLAB® XC8 C Compiler Version 1.20 Release Notes - Digi-Key

1. does not affect the operation of the actual pro ject MPLAB XC8 C Compiler Version 1 20 Release Notes 29 Selecting compiler mode When using the Free version of the XC8 compiler the ability to select compilation modes in the plugin is disabled If you switch to an older version of the com piler inside the MPLAB 8 plugin you will not be able to change the compilation mode to Standard or PRO To work around this behavior close the plugin then reopen it This should allow other compilation modes to be selected rfPIC12 parts To use the rfPIC12 parts for example the rfPIC12C509AF you will need to spec ify to the compiler a part name in a format similar to RF509AF for example You can also use an alias like 12CS509AF for example The full part name is also not appropriate when compiling from MPLAB IDE MPLAB IDE integration If Compiler is to be used from MPLAB IDE then you must install MPLAB IDE prior to installing Compiler 7 Microchip Errata For 8 bit PIC devices this release of the XC8 compiler recognizes the published silicon errata issues listed in the table below Some of these issues have been corrected and no longer apply in recent silicon revisions Refer to Microchip s device errata documents for details on which issues are still pertinent for your silicon revision The compiler s chip configuration file records which issues are applicable to each device Specific errata workarounds can be selectively enabled or disabled vi
2. in MPLAB IDE v8 would show elements of a structure array correctly Changes have been made to the compiler output to correct this MPLAB XC8 C Compiler Version 1 20 Release Notes 20 Redirecting function using psect pragma PICC 514 There were instances where use of the pragma psect would not appear to work as the name of the psect being redirected was changing as a result of psect merging by the assembler optimizer A new system of identi fying mergable and splittable psects was introduced which will assist in reducing this problem MPLAB IDE popup about source code using include PICC18 565 PICC18 566 If you are using any of the printf family of functions an MPLAB IDE popup may have appeared warning that The project contains source files that use the include directive from within a function to include source code Although this would not have affected normal debugging operations in this particular instance the trigger for message has been adjusted so that this message will no longer be produced Zeroing of config bits PICC18 600 If you used the PIC18 pragma to program only the lower byte of a configuration location the compiler may have zeroed the upper byte rather than use the default configuration value Ideally all configuration words should be specified in your programs or the RUNTIME option to program the device with the default config words should be enabled However this zeroing of he upper byte will no lon
3. integer quantity when it came to assignment Code that assigned a byte or larger integer to a single bit bit field may have failed Can t Generate Code for Duplicated Functions XC8 358 The compiler may have issued Can t Generate Code error messages in situations where a function was duplicated in inter rupt and main line code and this function used pointers Handling of incomplete types XC8 374 The parser was producing incorrect type information where a type used in a declaration was at that point incomplete e g if you used a struc ture tag in a declaration but that tag had not been defined The code generator would sub sequently crash if such incomplete type information was encountered types should always be defined before they are used but the compiler will no longer crash on such situations Testing of volatile bytes XC8 388 The code that tested volatile bytes variables for in e quality was using a MOVF x f instruction This was not in keeping with the spirit of the volatile keyword and could also play havoc with certain registers such as the TMRO register on some baseline devices such as the 10F222 which require a read delay after being written This code sequence is no longer used and access of SFRs will be well be haved Pointer assignment failure XC8 342 XC8 343 In some circumstances assignment of a struc ture member address to a pointer may have resulted in an incorrect destination pointer size being determined by
4. supported 8 bit PIC device from the one application A single device driver xc8 is used to invoke the compiler regardless of the target device This driver will invoke the appropriate internal applications based on your device selection The picc and picc18 drivers which controlled the former compilers are currently still employed and the baseline mid range and PIC18 code generator and assembler applications are still separate Only one copy of the generic applications such as the preprocessor cpp the parser p1 the linker hlink and utilities like hexmate objtohex and cromwe11 are included with the compiler and these are shared by all device targets MPLAB XC8 C Compiler Version 1 20 Release Notes 8 Operating modes The former HI TECH C Compiler for PIC18 MCUs only operated in a Lite or PRO mode With XC8 a Free previously called Lite Standard and PRO mode are avail able for all target devices 4 Migration Issues The following are features that are now handled differently by the compiler These changes may require modification to your source code if porting code to this compiler version The version number in the subheadings indicates the first compiler version to support the changes that follow 4 1 Version 1 20 G option disable The option that controlled generation of symbol files has been disabled This option was always selected in MPLAB IDE and there was never a need to disable this fea ture Symbol files are now al
5. the compiler This would have resulted in subsequent pointer derefer ences being invalid This problem was detected only with assignments to pointer parame ters as part of a function call but could have potentially occurred elsewhere Pointer access failure with duplicated functions XC8 377 If a function that has a pointer pa rameter is called from main line and interrupt code i e it is duplicated by the code genera tor the compiler may have issued a looping around allocGlobals or can t generate code error message In other situations the code may have compiled but accesses to the pointer may have been incorrect The issue could have affected any device with interrupts Undefined btemp symbol XC8 371 In some circumstances exacerbated by the use of a de bugger and devices with small amounts of RAM the internal compiler symbol btemp may not have been defined and an error results This symbol is now correctly defined Incorrect access of high program memory XC8 363 The compiler was not correctly setting the TBLPTRU register for accesses of absolute addressed const data located above OxFFFF in PIC18 program memory Incorrect configuration bit user ID settings XC8 385 Attempts to program the configuration bit or user ID settings may have failed due to a sorting bug that may have resulted in the bits being programmed in the wrong order The issue was inconsistent but could affect all devices MPLAB XC8 C Compiler Version 1 20
6. 0 Release Notes 11 Compiler drivers While you may continue to call the picc or picc18 command line drivers it is recommended that projects be swapped to use the unified xc8 driver Future compiler releases may discontinue the device specific drivers or additional functionality may be added to xc8 that will not be usable if you continue to use the device specific drivers FN type directives All FN type directives are no longer supported and should not be used Such directive include FNBREAK FNSIZE FNROOT etc The FNCALL and FNROOT directives are still issued by the compiler but it is recommended that these not be used in handwritten assembly code 5 Fixed Issues The following are corrections that have been made to the compiler These may fix bugs in the generated code or alter the operation of the compiler to that which was intended or specified by the user s guide The version number in the subheadings indicates the first compiler version to contain fixes for the issues that follow The bracketed label s in the title are that issue s identifi cation in the tracking database These may be of benefit if you need to contact support 5 1 Version 1 20 Bad conditional code XC8 640 An error in an assembler optimization that dealt with a bit test and skip instructions and FSR manipulations caused the sense of some conditional control statements to be inverted Phase errors XC8 590 XC8 691 XC8 49 The assembler optim
7. 55 PIC16F1459 PICI6LF1459 PIC16F1784 PICI6LF1784 PIC16F1786 PICI6LF1786 PIC16F1787 PICI6LF1787 PIC18F45K50 PIC18F24K5S0 PICI8F25K50 PICI8LF45K50 PICI8LF24K50 PIC18LF25K50 PIC18F97J94 PIC18F87J94 PIC18F67J94 PIC18F96J94 PIC18F86J94 PIC18F66J94 PIC18F95J94 PIC18F65J94 PIC18F85J94 PIC18F96J99 PICI8F86J99 PIC18F66J99 The Common C Interface CCI The Common C Interface is a documented set of ANSI stan dard refinements non standard extensions and guidelines to help you write code which is more portable across all MPLAB XC C compilers A new chapter has been added to the XC8 User s Guide describing these features User s guide A new compiler user s guide has been included with this release See the Documen tation Updates section above for more information Roam out Licensing A new roam out feature allows a network license to be checked out for an extended period for use on a particular computer While the license is checked out the computer has licensed use to an XC compiler and need not be in contact with the network license server When the license is returned to the network license server it is once more available to be used as a floating license or to be roamed out to other computers Psect allocation The CCI _ section specifier can also be used in non CCI mode Refer to the CCI chapter in the user s guide It can be used in place of the pragma psect direc tive Function and module information Information a
8. ATH environment variable On Linux systems the installer by default updates the PATH envi ronment variable to include paths to the new executables being installed If the installer is run via sudo the default action will update the PATH variable of the user executing the sudo command If the installer is run by root the installer will only update root s PATH variable and not the PATH variables of ordinary users If installing the compiler while logged in as root a better choice is to update a user PATH variables Alternatively skip the step to update the PATH variable in the installer and to update the PATH variables of users who will use the software manually C18 code compatibility The C18 code compatibility feature is only a beta implementation Leg acy C18 projects may not compile or compile with runtime errors when using XC8 Changing toolsuite in MPLAB IDE V8 If the toolsuite associated with an MPLAB IDE v8 pro ject is changed from the HI TECH Universal toolsuite to the XC8 toolsuite or vice versa the selected options in the original toolsuite are not copied over to the new toolsuite Please note all options before you switch and confirm the options in the new toolsuite IDE plugin overwrite XC8 360 XC8 367 If an older compiler is installed after installing a newer compiler the new IDE plugin may be overwritten The 1 01 compiler installer is known to overwrite the 1 10 plugin You can manually reinstall the new plugin withou
9. CI8F24K50 and PIC18F25K50 The peripheral li braries for all supported devices have been updated to the latest code base New parsing option A new driver option has been added that alters the generation of intermedi ate files produced by the parser The option is PARSER and can be set to lean or rich The lean suboption the default will not include unused symbols in intermediate files These are included when selecting the rich suboption but not that this setting will generate larger intermediate p code files and will slow down the compilation considerably The MPLAB XC8 C Compiler Version 1 20 Release Notes 6 operation of prior versions of the compiler was equivalent to the rich setting Use the rich setting if you need unused symbols to be included in the link stage New enhanced mid range errata workaround The compiler now has the ability to employ an errata workaround for some enhanced mid range devices This is controlled by the ER RATA option CLOCKSWw which is used to control other PIC18 errata workarounds The workaround will affect the device startup code but is not enabled by default Check your device literature to see if this workaround should be enabled 3 4 Version 1 10 New device support The following parts are now fully supported by this release MCP19110 MCP19111 RF675F RF675H RF675K PIC12F529T39A PIC12F529T48A PICI2LF1840T39A PIC12LF1552 PIC16F527 PICI6F1454 PICI6LF1454 PIC16F1455 PICI6LF14
10. MPLAB XC8 C Compiler Version 1 20 Release Notes Produced on Wednesday 12 June 2013 THIS FILE CONTAINS IMPORTANT INFORMATION RELATING TO THIS COMPILER PLEASE READ IT BEFORE RUNNING THIS SOFTWARE Overview Introduction Previous Versions System Requirements Devices Supported Editions and License Upgrades Installation and Activation Compiler Documentation Customer Support Documentation Updates New Documents User s Guide Clarifications and Corrections Checksums Local Variable Qualification Assembly Code Deviations Device Family Macros Disabling Optimizations Fletcher s Algorithm New Error Warning Messages What s New Version 1 20 Version 1 12 Version 1 11 Migration Issues Version 1 20 Version 1 12 Version 1 11 Fixed Issues Version 1 20 Version 1 12 MPLAB XC8 C Compiler Version 1 20 Release Notes OONHNNDAAAaAnnhF HPA HA HPWWWNNNNN LN Se MANN OO Version 1 11 15 Known Issues 24 Microchip Errata 30 1 Overview 1 1 Introduction This is a major update to the Microchip MPLAB XC8 C compiler This compiler version introduces a significant new feature generation of ELF DWARF debug ging files In addition there is new part support and fixes to a number of reported bugs Previously two HI TECH C compilers supported Microchip 8 bit PIC devices HI TECH C Compiler for PIC10 12 16 MCUs and HI TECH C Compiler for PIC18 MCUs MPLAB XC8 replaces both these compilers and supports all 8 bit PIC devices released as o
11. Release Notes 17 Improved error relating to IDLOC XC8 384 If non hex digits were used in for any nibble in the IDLOC macro a confusing error was issued A new message 1436 has been created for this situation 5 5 Version 1 01 Looping around allocGlobals error XC8 318 This error may have been triggered but is not specific to any particular code sequence The compiler has been updated to ensure this trigger will not result in this error Access of char arrays XC8 304 If the index expression used with an array of char consists of a non constant expression e g a plain variable from which is subtracted a constant e g myArray idx 1 then the index calculation may have been incorrect and the wrong element accessed This issue mostly affected PIC18 devices and arrays no larger than a bank It may have affected enhanced mid range parts with array sizes larger than 256 bytes The issue has been resolved for all devices Code jumps to wrong location XC8 295 If the assembler optimizer is enabled assembly code that directly wrote to the program counter may have been abstracted which may have caused a jump to the wrong location and code failure C code affected would produce a lookup table of some description but it unlikely that C code would trigger this issue Hand written assembly would only be affected if the option to optimize assembly source files was enabled Duplicated SFRs XC8 319 Some SFR bit field structures had dup
12. Structures which are auto cannot be initialized Simply define the structure and assign values separately EEPROM variable limitations There are some limitations to using variables qualified as ee prom aside from them being not supported at all on PIC18 devices Avoid using these variables in complicated expressions and remember that code which accesses such objects is complex and very slow Size of EEPROM arrays Arrays that qualified as eeprom and which are initialized may not have all initial values written to the EEPROM Constant index into int array If a constant is used as the index into an array of const int type the element read may be incorrect This issue does not affect arrays of different types or when the index is a variable Absolute initialized variables Variables which are absolute and which are not const cannot be initialized The following example will not generate an error but will not work as ex pected Define the variable as absolute and initialize it in main line code unsigned int varname 0x0200 0x40 will not work as expected Stack overflow When the managed stack is used the stackcal1 suboption to the RUNTIME option is enabled in some situations the stack may overflow leading to code failure With this option enabled if a function call would normally overflow the stack the compiler will automatically swap to using a lookup table method of calling the function to avoid the overflow However if the
13. a the driver s ERRATA command line option All these errata are PIC18 specific ex cept for the CLOCKSW errata which applies to enhanced mid range devices Execution of some flow con trol operations may yield un expected results when in structions vector code execu tion across the 4000h address boundary Each block of program code is not allowed to grow over the 4000h address boundary Additional NOP instructions are inserted at prescribed lo cations MPLAB XC8 C Compiler Version 1 20 Release Notes FASTINTS LFSR MINUS40 RESET BSR15 If a high priority interrupt occurs during a two cycle instruction which modifies WREG BSR or STATUS the fast interrupt return mecha nism via shadow registers will restore the value held by the register before the instruc tion Using the LFSR instruction to load a value into a speci fied FSR register may also corrupt a RAM location Table read operations above the user program space gt 1FFFFFh may yield erro neous results at the extreme low end of the device s rated temperature range 400 C A GOTO instruction placed at the reset vector may not exe cute Peripheral flags may be erro neously affected if the BSR register holds the value 15 and an instruction is executed that holds the value C9h in its 8 least significant bits MPLAB XC8 C Compiler Version 1 20 Release Notes Additional code reloads the shadow registers with the cor rec
14. al different operating modes Free Standard and PRO The Standard and PRO modes are licensed modes and require a key for activation ob tained after purchase These two modes offer two levels of improved optimization features com MPLAB XC8 C Compiler Version 1 20 Release Notes 2 pared to the Free mode A compiler operating in Free mode can be operated indefinitely without a license You can change to any operating mode license permitting from the MPLAB X IDE project properties or MPLAB IDE v8 Build Options on a build by build basis The compiler can be evaluated in any licensed mode for 60 days free of charge After the evalua tion period has expired the compiler reverts to the Free mode and the trial optimization features are disabled You can choose the operating mode or choose to evaluate the compiler during the installation and activation process 1 6 Installation and Activation See also the Migration Issues and Limitations sections for important information about the latest license manager included with this compiler If using MPLAB IDE be sure to install MPLAB IDE v8 10 or later or MPLAB X 1 2 or later before installing these tools Quit the IDE before installing the compiler Run the exe Win dows run Linux or app OS X compiler installer application e g XC8 1 00 11403 windows exe and follow the directions on the screen The default installa tion directory is recommended If you are using Linux you must i
15. ated with taking the ad dress of enumerated objects Qualifiers silently ignored for local objects XC8 670 Objects which are local to a function including auto and static local objects cannot be qualified as far or near The compiler was not indicating that the specifier was being ignored A warning is now issued for such definitions Absolute addresses silently ignored for local objects XC8 652 Objects which are local to a function including auto and static local objects cannot be made absolute The compiler was not indicating that the or _ at construct was being ignored A warning is now is sued for such definitions Linear memory allocation of objects XC8 501 Absolute objects that specified a linear mem ory address may not have been allocated correctly if the object s equivalent banked ad dresses mapped into the common memory This only affected enhanced mid range devices and objects that were not large enough to be automatically allocated to linear memory The compiler now correctly allocates these objects Identical case label values in a switch statement XC8 493 The compiler was not detecting the use of more than one identical case label value inside a switch statement This is now correctly identified and will trigger an error __DEVICENAME _ not defined XC8 659 This predefined macro was not being defined by the compiler This is now defined unconditionally Procedural abstraction of in line assembly code XC8 660 T
16. bout each function which appears in the as sembly list file is now also displayed in the map file In addition a summary of program memory usage on a module by module basis is shown in the map file This allows an esti mate of the size of the code excluding data being generated by each module Bank specification with PIC18 devices The qualifiers banko through bank3 may now be used with PIC18 devices to allocate variables to a specific memory bank These qualifiers must be used with the ADDRQUAL option Implementation of strftime function The strftime function has been implemented and is available in the standard libraries MPLAB XC8 C Compiler Version 1 20 Release Notes 7 Qualifier synonyms A side effect of the CCI features is that when not in CCI or strict ANSI mode most of the non standard specifiers e g bit near and far can also be represented with two leading underscores asin bit nearand far ete SFR structure types The structures that are defined to represent SFRs are now a typedef type that is available for general use Function in lining A new qualifier inline can be applied to some C functions A call to any function thus qualified will not generate a call return sequence but will be replaced by the assembly code associated with the function body This expansion will save stack usage and may reduce code size if the function body is small The assembler has always had the ability to inline small assembly sequ
17. ce data sheet MPLAB XC8 C Compiler Version 1 20 Release Notes 18 Bad access at start of function XC8 94 The code at the beginning of function could have ac cessed the wrong address bank for a variable if the compiled stack was built up over mul tiple banks and WREG was used to pass a function argument Incorrect RAM ranges with 12F1501 XC8 274 The RAM ranges associated with this device did not reserve the memory from 50 6F Allocation of user defined objects to this memory may have caused code failure Bad results with 24 bit expressions XC8 227 The code generated for some arithmetic and bitwise operations involving 24 bit integers were missing some necessary bank selections which may have generated wrong results Compiler crash with conditional operator XC8 117 Assigning a pointer the result of an ex pression using nested conditional statements could have caused the compiler to crash for PIC18 devices Bad results with long arithmetic XC8 241 The results of some long arithmetic expressions may not be correctly assigned due to a bank selection bug Build errors in MPLAB X IDE XC8 101 XC8 104 Source file paths that contained spaces were being written to the dependency files without the spaces escaped This resulted in these files containing erroneous targets and dependancies which may have resulted in in correct builds In addition the preprocessor would generating a dependency file for assem bly modules incorrectly ass
18. ch term A How to chapter gives an swers to common questions relating to the compiler and writing programs 1 8 Customer Support MPLAB XC8 C Compiler Version 1 20 Release Notes 3 Common problems are explained in the FAQ list You can also ask questions of other users of this product in the XC8 Forum Microchip welcomes bug reports suggestions or comments regarding this compiler version Please direct any bug reports or feature requests via the Support System At times advisory message 1395 may be issued by the compiler This message is part of a new testing process The compiler will display this message if it encounters a specific code sequence that results in internal compiler templates being used in a unique way This message does not im ply a bug in the generated code however the code sequence encountered could be used to fur ther improve the compiler s performance If you wish to participate by contributing the code that generated this message you are welcome to send the project to Support otherwise you may ig nore this message 2 Documentation Updates 2 1 New Documents The user s guide associated with this 1 20 version has been updated The guide details new com piler features and expands the description of some existing features A PDF version of the PIC18 peripheral library document has been added to the compiler docs directory This indicates those functions which are relevant to each device and the library int
19. ed for Enhanced Mid range devices that are large and placed in the linear memory space MPLAB IDE v8 shows these objects are being out of bound This is display issue and is not indicative of code failure Variables shown in wrong memory space If an object is made absolute and allocated address 0 it may only be visible in the program memory view of MPLAB IDE v8 This is purely an IDE view issue and does not impact on the code operation Wrong watch values MPLAB IDE v8 may show incorrect values for pointers and any object located after a pointer in a structure The COFF debug format used by this IDE does not allow the compiler to specify the necessary size information for pointer variables The compiler makes pointers a certain size based on their usage whereas the IDE assumes all pointers are one fixed size This can make viewing pointers hit and miss Any attempt to examine pointers in the IDE s Watch view may result in incorrect values being shown or an invalid message being displayed in the view In addition if a pointer is a member of a structure any member of any type located after the pointer in the structure s memory may also be shown incorrectly in the Watch window The actual contents of the pointer and pro gram execution are not affected If you are using MPLAB X IDE then use the new ELF DWARF debug format as this allows accurate size information to be specified and will eliminate the issue Switch strategies There is only
20. en changed What was the in line pragma is now known as the intrinsic pragma Since the inline pragma was not intended to be used with user defined routines this should have no impact on existing pro jects Use of the inline pragma in this compiler version will be ignored however future versions may implement a user operable inlining feature Filling unused values The FILL option which is used to fill unused memory locations now assumes the value specified is a 2 byte word Previously the size of this value was the same as the target device program memory addressability i e 1 for PIC10 12 16 devices and 2 for PIC18 devices The width of the value can always be specified with the option See the user s guide section relating to hexmate 4 6 Version 1 00 Library functions removed The following library functions and macros are now longer sup ported and have been removed from the libraries and header files device id read e idloc read e idloc write Ea e config read e config write checksum8 and the macro CHECKSUM8 checksum16 and the macro CHECKSUM16 checksum32 and the macro CHECKSUM32 Any attempt to use these will result in a compiler error Memory functions replaced by peripheral library equivalents Flash and EEPROM functions and macros have been removed from the compiler libraries and header files They have been replaced with those in the peripheral library MPLAB XC8 C Compiler Version 1 2
21. ences so code size reductions may not be large The operation of this qualifier is similar to use of the new pragma inline directive The previous version 1 00 and earlier inline pragma implementation has been renamed to instrinsic See Migration Issues below Assembly psect flags To support function inlining two new psect flags have been added in line and keep These indicate to the assembler respectively that the contents of a psect may be inlined and then removed and that the contents of a psect may be inlined but must never be removed 3 5 Version 1 01 Enhanced PIC optimizations New optimizations specifically aimed at the enhanced mid range PIC devices have been added These optimizations reduce code size and target any code that indirectly accesses locations via the FSR registers 3 6 Version 1 00 Psect merging and splitting Two new PSECT directive flags have been added to allow splitting or merging of psects by the assembler optimizer Now by default no splitting or merging takes place but the use of the split allow and merge a_1 low flags can indicate that these optimizations can take place See the assembly language chapter in the user s guide Unified 8 bit device support This compiler unifies the two former HI TECH C compilers which previously supported Microchip 8 bit PIC devices HI TECH C Compiler for PIC10 12 16 MCUs and HI TECH C Compiler for PIC18 MCUs This MPLAB XC8 compiler supports compilation for any
22. ensions accepted by the compiler are those belonging to the Common C Interface IAR compatibility mode or the native XC8 syntax respectively All of these extensions are discussed in the user s guide Expanded hardware multiply usage The PIC18 hardware multiply instructions are now used for 16x16 bit integer multiplication The library routine that implements this feature breaks the multiplication into several operations that can use the 8 bit hardware multiply instruc tion The 32 bit integer multiplication routines continue to use an iterative solution and do not use these instructions New listing option Previously a C list file was produced for each C source file being compiled If an assembly list file was request which is the default in MPLAB IDE then these listing files were overwritten with the assembly listing content The C listing files are no longer produced by default If you would like C listing files to be generated a new option CLIST has been added to request this action 3 2 Version 1 12 New Device Support The following parts are now fully supported by this release MCP19114 MCP19115 PICI6LF1824T39A PIC16F570 PIC16F753 and PIC16HV753 3 3 Version 1 11 New Device Support The following parts are now fully supported by this release PIC16F1788 PIC16F1789 PICI6LF1788 and PICI6LF1789 New peripheral libraries The following devices and their LF counterparts now have periph eral library support PIC18F45K50 PI
23. ent the assembler optimizer from optimizing access to volatile bit objects Although the code would have been functionally correct subsequent optimizations may have caused runtime failures This correct information is now generated and volatile bit access will not be optimized unexpectedly MPLAB XC8 C Compiler Version 1 20 Release Notes 22 vprintf and vsprintf linker errors PICC 524 PICC 619 Trying to use either of these func tions may have resulted in the undefined symbols _ doprint vprintfor vsprintf These routines are now fully supported in the libraries and can be called Upper bound of mktime PICC18 126 The mkt ime function had a upper limit of the year 2020 higher values would return incorrect results This limit has now been extended to the year 2038 Bad call to subtype with regsused pragma PICC18 392 If using the regsused pragma for a function before the definition of that function this error occurred This has been corrected and the pragma can be used at any point in the source code Looping around allocGlobals error PICC 570 This error may have occurred in some situa tions particularly when NULL pointers were being assigned in the source code This has been corrected Read of wrong array element PICC 542 When reading a const array using a constant index in some situations the wrong element may be read This bug did not affect array access using a variable or other expression as the index Memory allocation A
24. er face 2 2 User s Guide Clarifications and Corrections The following sections provide additional information to that found in the user s guide shipped with the compiler 2 2 1 Checksums The information contained in the user s guide relating to the generation of checksum values Sec tions 4 8 17 CHECKSUM Calculate a Checksum and 8 5 1 5 CK does not clearly indicate that when selecting any of the Fletcher algorithms this selection overrides any width specified Algorithm 7 Fletcher 8 will always reserve 2 words for the checksum value Algorithm 8 Fletcher 16 will reserve 4 words for the checksum value 2 2 2 Local Variable Qualification In sections 5 4 8 2 Near Type Qualifier and 5 4 8 3 Far Type Qualifier they indicate that auto objects cannot use either the near or far specifiers This text should indicate that all local vari ables even static local objects cannot use the near or far specifiers The same objects also cannot be made absolute see Section 5 5 4 1 Absolute Variables in Data Memory 2 2 3 Assembly Code Deviations Section 6 4 1 Assembly Instruction Deviations does not list the format for the index form of the MOVIW and MOVWT instructions MPLAB XC8 uses the form MOVIW k FSRn MPLAB XC8 C Compiler Version 1 20 Release Notes 4 for both instructions 2 2 4 Device Family Macros When compiling for PIC18 devices a macro that indicates the device family is defined by the compiler For example
25. f this time 1 2 Previous Versions The previous version MPLAB XC8 C compiler was 1 12 released November 2012 The last released version of HI TECH C Compiler for PIC10 12 16 MCUs was 9 83 released in September 2011 The previous HI TECH C Compiler for PIC18 MCUs was 9 80 released in Oc tober 2011 1 3 System Requirements The MPLAB XC C compilers and the licensing software they utilize are available for a variety of operating systems including Microsoft Windows XP Professional SP3 Vista SP1 Windows 7 Professional Ubuntu 9 10 or Mac OS X 10 5 The compiler may also run on the various other Linux distributions such as Oracle Enterprise Linux 5 Ubuntu 8 x and 10 04 Red Hat Enter prise Linux If you are running a license server only computers with operating systems supported by the compilers may be used to host the license server The license server does not need to run on a server version of the operating system And specifically Microsoft Windows Server platforms are not supported by the compiler 1 4 Devices Supported This compiler supports all known 8 bit PIC devices at the time of release See pic _chipinfo html in the compiler s doc directory for a list of all supported baseline and mid range devices and pic18 chipinfo html for a list of all supported PIC18 devices These files also list configuration bit settings for each device 1 5 Editions and License Upgrades The MPLAB XC 8 compiler can be activated in sever
26. forms Bank selection issue XC8 494 In an expression such as A B C where A and C are unsigned 16 bit objects in different banks and B is an unsigned char a bank select instruction may have been omitted resulting is the wrong value being assigned to the destination variable 5 3 Version 1 11 Compilation times XC8 441 Large projects particularly those targeting PIC18 devices may have experienced increased compilation times This was due to the compiler processing more symbols A new option has been added and enabled by default to limit the symbol list The new option is PARSER See the New Features section for more information Looping around pointGraphComplete Error XC8 442 A non deterministic pointer related issue was causing this error to be printed and terminating compilation Debugging absolute objects XC8 447 Some SFRs and absolute addressed objects residing in RAM would appear as being located in program memory during a MPLAB X or v8 debug ging session The content of these values would thus be incorrect Absolute symbols should now appear to be located in their correct memory space and their contents shown correctly Parsing of config pragma arguments XC8 452 The parsing of arguments to the pragma config directive was erratic when it came to quoted arguments The quote character is now a token delimiter and you may quote the arguments to this pragma e g WDTEN ON MPLAB XC8 C Comp
27. ged Provided code included the generic and recommended lt xc inc gt assembly header file then this will be transparent Specifically changes relate to using the extension inc instead of h for assembly domain header files the names of device specific assem bly header files now match their C domain counterparts Deprecation of in line assembly header files The PIC10 12 16 header files that were usable from assembly that was in line with C code have been remove These header files were MPLAB XC8 C Compiler Version 1 20 Release Notes 10 previously included via the generic file lt caspic h gt The content of these files will be in cluded once you include lt xc h gt in your C source code Removal of single letter bit definitions The definitions for SFR bits that used a single letter identifier have been removed for example the SSP1CON register bit S These register bits are still available in the corresponding SFR structures for example SSP1CONbits sS The absence of these very poorly chosen identifiers should not be missed 4 5 Version 1 01 Missing SFR definitions There have been changes to the header files to ensure correlation with the data sheet This may resulted in some SFR definitions being no longer available If you see undefined symbol errors or other build errors relating to SFR names please refer to the appropriate device specific header file and update your code The inline pragma The much misused inline pragma has be
28. ger occur Undefined symbol with empty loops PICC18 524 The compiler an remove some condition code if the state of variables used in the controlling expressions are know In some in stances where the true or false statements were an empty loop e g while the compiler may have deleted a label that was still being referenced by other code This would have produced an undefined symbol which might look something like 19 Crash with undefined functions PICC18 532 If function that were not defined were assigned as the target of a function pointer the compiler may have crashed This crash has been fixed and now the linker will report the symbols as being undefined as expected Errors indicated in unused files PICC 428 When an error indicating a variable is too large is emitted the name of the file that contained the variable definition may have indicated a source file that was not in the project such as a library file Assignment to structure ignored PICC 433 In situations where an assignment is made to a structure is followed by an assignment to a bitfield within that structure the initial assign ment may be removed This would only occur in PRO mode This has now been fixed and the compiler notes the distinction between the objects accessed Compiler crash and old library modules PICC 573 The compiler may have crashed is some library modules were used from the SOURCES directory of the compiler This directory no longer include file
29. gger an error from the parser Can t generate code for library string routines XC8 413 Some string library functions may have caused can t generate code errors These have been adjusted to ensure correct com pilation Assignment to volatile bytes XC8 427 In some operating mode when assigning 1 to a volatile byte variable it may not have been updated atomically with one write rather than clear and increment instruction This problem did not affect absolute objects and may have only caused runtime problems if the byte was accessed from main code and interrupt ROM option The RoM option was not processing its arguments correctly which may have resulted in it not reserving the memory specified 5 4 Version 1 10 Using far with Functions XC8 337 If the far qualifier was used with functions it confused the compiler into thinking the function identifier was that of a variable destined for RAM This may have triggered an error if no far memory was defined or caused a runtime code failure Non functional ADDRQUAL option XC8 293 The reject suboption of this option was not working correctly for PIC10 12 16 device The require and request suboptions MPLAB XC8 C Compiler Version 1 20 Release Notes 16 were not working correctly for PIC18 devices This option should now work as expected for all devices Conversion of integer to bit field XC8 353 The compiler was treating single bit bit fields as a boolean rather than an
30. have crashed if encountering information gener ated from static bit objects that are absolute Crash with malformed warning pragma PICC 610 If the message number s were omitted from the pragma warning disable directive the compiler crashed An error is now emitted if this situation is encountered Read of write only registers PICC 658 If an attempt was made to read a Baseline device write only register e g TRIS the compiler would produce a can t generate code error mes sage A more specific message is now produced alerting you to the offending operation Can t generate code PICC 683 PICC 499 The compiler was not able to generate code for some expressions involving logical or bitwise operation on bit objects This has been cor rected Prototype for eeprom_write PICC 675 The prototype for eeprom write incorrectly stated that this function returned a value This was not correct and the prototype now indicates a return type of void CLRWDT appearing in _delay output PICC 460 For some delay values the delay in line function for PIC18 targets only produced CLRWDT instructions as part of the delay This has been corrected and a NOP is used instead For PIC18 targets you have a choice of delay or delaywdt to implement in line delays which do not use and use respectively the CLRWDT instruction as part of the delay Optimization of volatile bits PICC 606 The compiler was not generating the appropriate in formation to prev
31. he assembler optimizer was per forming procedural abstraction on assembly code that was placed in line with C code The MPLAB XC8 C Compiler Version 1 20 Release Notes 13 optimizer should not perform any optimization of in line assembly code The optimizer has been prevented from performing these optimizations BSR register not recognized by regsused pragma XC8 663 Any attempt to list the BSR reg ister in the regsused pragma would have resulted in an error This has been corrected and this register may now be used with this pragma for those devices that implement this regis ter Allocation of PIC18 far variables XC8 582 In some instances far qualified variables may have been linked at address 0 not in the memory defined as the far RAM Indexing array with constant expression failure XC8 648 With enhanced mid range devices only any operation that involved adding a integer constant to an address typically this will be an array access with a constant integer index may have caused subsequent code to fail Such code was not correctly reporting its use of WREG Initialization of large objects on enhanced mid range device XC8 672 Initialization of large objects such as arrays or structures that contained a pointer may not have been assigned the appropriate values by the runtime startup code This only affected PIC16F1xxx devices Uninitialized const objects not assigned zero XC8 553 If const objects were not initialized they were n
32. iler Version 1 20 Release Notes 15 Doing so will avoid any macro substitutions by the preprocessor If you have defined mac ros for ON OFF or any other token used by the config pragma consider quoting the pragma arguments or moving the pragmas to a module that is not exposed to your macros Incorrect access of array of strings XC8 454 Code which used a variable to access an ele ment of a string array may have failed when the index was non zero Unsupported short long message using CCI XC8 429 When using the CCI a warning may have been issued indicating that the short long type was not supported The header files that referenced this type have been updated and use a plain long type when compiling for the CCI Undefined symbols with bitwise operations XC8 424 Some bitwise operations for example or amp when used in functions that were in the interrupt call graph may have produced code that contained references to undefined temporary symbols Such symbols would look similar to i2u49 41 Can t generate code with printing floats XC8 108 For some placeholders associated with float types a can t generate code error may have been triggered with s printf This has been corrected Detection of incomplete types XC8 109 The parser was not detecting definitions using in complete types for example typedef struct foo foo t where foo has not been defined Pad foo t x Code which is defined in such a way will now tri
33. ine devices most notably the 12F529T39A and 12F529T48A the compiler may have attempted to use the non existent RETURN instruction instead of a RETLW instruction MPLAB XC8 C Compiler Version 1 20 Release Notes 14 Partial access to ID locations UDBC 678 The compiler did not allow access to the entire ID location for devices that implement this memory as being 14 bits wide e g the PIC16F1503 This has been corrected and you may now program all the bits of these ID locations Code failure accessing absolute objects straddling a bank XC8 601 The wrong bank may have been selected when accessing absolute objects that straddle a bank boundary Code may have failed when accessing the addresses in banks following that of the bank of the object s base address 5 2 Version 1 12 Compile times and crash XC8 127 A sorting issue related to pointer variables may have sig nificantly increased the compilation time of projects Not all projects were affected by this issue This issue may also have caused the code generator to run out of memory or even crash in some situations Compile times XC8 498 A further issue affecting compilation times was corrected This issue affected the assembler when ASMLIST was used This option is on by default when us ing the IDE Installer operation The installer program was not correctly setting the write permissions for some files This was reported on Windows XP but may have affected other plat
34. izer was removing redundant page selection instructions but other parts of the assembler where not taking this into ac count This created a mismatch in expected and actual sizes of some jump instructions which led to phase errors being produced This issue affected hand written and compiler generated assembly code Absolute function placement XC8 203 The address specified for functions made absolute was rounded down to the nearest 0x10 value So for example if you attempted to place a function at address 0x56 it was actually located at address 0x50 This only affected pro grams compiled for PIC18 devices Missing errata NOP instructions XC8 692 The assembler was not correctly adding in NOP instructions that form part of the fetch errata workarounds for some PIC18 devices See the user s guide ERRATA option section for more information Delay routines that re quired these instructions were known to run too fast A consequence of this fix is that code size will increase for devices that require the fetch errata workarounds Wrong UINT24_ MAX value XC8 565 The value for this lt stdint h gt macro was higher by 1 than it should have been Bad variable access after calls XC8 694 The compiler was on occasion placing a bank se lection instruction before the call to a routine This bank selection was not properly being tracked and may have resulted in incorrect access of objects once in the called function MPLAB XC8 C Compile
35. licate entries in the device specific header files and have been removed Bit objects on baseline devices Uninitialized global bit objects may not have been zeroed for baseline devices and in some instances the generated startup code may have corrupted other memory locations or caused the device to restart Call graph inconsistencies The call depth of some functions was not correctly indicated in the call graph shown in the assembly list file The total amount of auto parameter and tempo rary variable usage was also incorrectly displayed for some functions in the call graph Wide bit fields in header files XC8 289 Some header files were being generated with SFR bit fields that were wider than a byte This is not allowed by the compiler Such definitions are no longer contained in the header files Wrong external memory access XC8 286 The EMI options was not correctly being proc essed and this may have meant that access to external memory may have been incorrect Only several PIC18 devices have such memory Error on assembly directives after including header file XC8 285 After including the xc8 inc header file into assembly code some assembly directives e g the DS directive may have generated an error This was due to SFR names conflicting with the directive s name The header files will on longer use any SFR name that conflicts with a directive This will mean that SFR names may not always match those listed in the devi
36. mory restrictions The previous limitation which restricted memory to the first 4 RAM banks for user defined variables has been lifted Note however that the compiler will not allow you to define objects that span multiple banks on these devices In line delay values The delay value specified with the in line delay function _ delay is lim ited to 179 200 on PIC18 devices With PIC10 12 16 devices this value may be up to 50 659 000 In line delays On PIC10 12 16 targets the only in line delay function implemented is delay This uses NOP instructions when required as part of the delay sequence There is currently no equivalent version of this function that uses the CLRWDT instruction The function de laywdt which is available for PIC18 targets does use the CLRWDT instruction Watching const values in MPLAB v8 MPLAB IDE v8 cannot correctly display in the Watch view any object qualified as const and stored as RETLW instructions in memory Any const object compiled for a PIC18 device will be observable and this issue does not affect MPLAB X IDE Use of hardware multiply The PIC18 hardware multiply instruction is not used for any 32 bit multiply operations A library multiply routine is used for such operations The hardware multiply instruction is used for 8 and 16 bit multiplication Disabling function duplication XC8 3 The interrupt level pragma current does not pre vent duplication of functions called from both main line and inte
37. n improved memory allocation scheme is used when variables are quali fied as being in a particular bank or near and the ADDRQUAL option is set to require This will reduce the likelihood of Can t find space errors from the linker Code generator crash with undefined functions PICC18 532 If a function pointer was as signed the address of a function that is defined in external code the code generator may have crashed External functions might include those defined in assembly source code This only affect PIC18 targets Can t generate code errors with nested structures PICC 628 This error may have occurred for code that accessed bit fields within structures that themselves were members of other structures No stack allocated to function error PICC 611 PICC 485 PICC 416 PICC 637 This error is now unlikely to be triggered by code It was most likely to occur with complex expres sions particularly involving floating point arithmetic Can t generate code errors with short long types PICC 632 Some assignment operations on short long types e g amp and etc may have triggered a can t generate code error when compiling for baseline or mid range parts The ability to generate code for such ex pressions has been enhanced Parser crash with bad identifiers PICC 622 The parser p1 may have crashed if certain keywords were used as a variable identifier e g if you were to try to define a variable with the name eeprom A crash ma
38. ng point arithmetic and particularly those devices with less than 4 bytes of common memory available MPLAB XC8 C Compiler Version 1 20 Release Notes 28 Indirect function calls The parameters to functions called indirectly via a pointer may not be passed correctly if the following conditions are met e A function is called indirectly from both main line and interrupt code e This function has parameters The function pointer used to call this function is also assigned the address of other func tions at some point in the program and e This function pointer is initialized when it is defined All other instances of indirectly calling a function even from interrupt and main line code will work as expected option and tris For baseline devices the OPTION and TRIS registers must be written as a byte Writing individual bits is not supported PIC17 support PIC 17 devices for example 17C756 is not supported by this compiler fast32 floats The option to select the fast 32 bit float or double library for PIC17 devices that was included in the PICC STD compiler is no longer available Procedural abstraction An instance has been seen but not resolved which appears to be related to the procedural abstraction optimization of the assembler If suspect behavior is encoun tered compiling for speed instead of space will disable this optimization and allow you to confirm if this is the underlying cause This problem was reported f
39. nstall the compiler using a terminal and from a root account Install using a Mac OS X account with administrator privi leges The option Update MPLAB IDE to use XC 8 for existing C18 projects if set will change your MPLAB IDE settings so that all existing legacy projects designated to use either MPLAB C18 or MPLAB C Compiler for PIC18 MCUs will by default use this MPLAB XC8 compiler in C18 compatibility mode To revert this change if you select it here you will need to manually adjust the toolsuite settings for legacy projects that should continue to use the MPLAB C18 or MPLAB C Compiler for PIC18 MCUs compilers This option has no effect if you do not have legacy pro jects Activation is now carried out separately to installation See the document License Manager for MPLAB XC C Compilers DS52059 for more information The XC License Manager now supports roaming of floating network licenses Aimed at mobile users this feature allows a floating license to go off network for a short period of time Using this feature you can disconnect from the network and still use your MPLAB XC compiler See the doc folder of the XCLM install for more on this feature MPLAB X IDE v1 40 includes a Licenses window Tools gt Licenses to visually manage roam ing 1 7 Compiler Documentation The compiler s user s guide covers all aspects of the compiler s operation as well as other useful information Check the well populated index for your sear
40. nt MOVLP instructions XC8 49 Redundant MOVLP instructions were being pro duced for some call sequences for Enhanced mid range devices 5 6 Version 1 00 Bogus warning on B option XC8 11 If compiling under MPLAB V8 in some instances a warning indicating that the B option was defunct was issued This option is indeed de funct but the compiler has been adjusted so that this is not produced when compiling un der the IDE Parser crash PICC18 618 If an unexpected attribute was used with function definitions e g __attribute _ const the parser crashed instead of giving an error This has now been corrected Parser crash PICC 684 PICC 688 PICC18 596 PICC18 607 PICC18 616 PICC18 619 PICC18 620 PICC18 621 In some circumstances the parser would crash when encoun tering illegal or unusual source code This has been seen with code that accesses some structure members passing malformed arguments to functions or with non prototyped K amp R function definitions Changes to the parser should prevent the application crashing Bad code associated with negation PICC 652 In certain cases negating a 16 bit integer may have overwritten WREG This has been corrected Crash on structure with no members PICC 597 If a structure was defined that had no mem bers the parser application crashed This has been rectified Arrays of structures in MPLAB not watchable PICC 544 PICC18 593 In some circum stances the watch window
41. one possible switch strategy currently available for PIC18 de vices It uses the space switch type New strategies will be introduced in future compiler versions so that PIC18 devices have similar options to the baseline mid range devices Copying compiler header files The header files shipped with the compiler are specific to that compiler version Future compiler versions may ship with modified header files If you copy compiler header files into your project particularly if you modify these files be aware that they may not be compatible with future versions of the compiler SFRs for 12LF1840T48A The following are inconsistent in this device s header file e DACNSS bit not defined in DACCONO register 118h e SSP1M0 SSP1M1 SSP1M2 SSP1M3 SSPEN SSP10V defined as SSPMO SSPM1 SSPM2 SSPM3 SSPEN SSPOV in SSP1CON1 register 215h SFRs for 16 L F1507 The following are inconsistent in this device s header file e In NCO1ACCU 49Ah NCO1ACC lt 23 20 gt not defined e CWGIASD register 695h defined as CWG1CON2 Initialization of eeprom arrays Initialization of large arrays that are qualified eeprom may fail on enhanced mid range devices When the size of these arrays exceeds the size of the free MPLAB XC8 C Compiler Version 1 20 Release Notes 27 space in each GP RAM bank the compiler tries to allocate the array to the linear RAM space not EEPROM Small arrays are not affected by this issue Initialization of auto structures
42. or an Enhanced Mid range device Pointer assignments In PRO mode if a pointer assignment is made where one of the pointers is a member of a structure the compiler may fail to copy the whole pointer causing the pointer to register an incorrect address Configuration words PIC18 parts only The new device support introduced in PICC18 v9 80 will not automatically program the default values into the configuration words when no value is specified If your project does not program all configuration words explicitly se lect the option Program the device with default config words in the Linker tab Specifying configuration words on PIC10 12 16 devices The PROG CONFIG and CON FIG macros can be used to specify the configuration words on PIC10 12 16 devices as well as PIC18 devices The PROG _CONFIG macro must use a literal constant argu ment you cannot use the configuration setting symbols with this macro The CONFIG macro must only use the predefined configuration setting symbols and you may not not use a literal value with this macro MPLAB 8 debugging information When compiling projects with multiple C files MPLAB may throw up a warning dialog with the message beginning The project contains source files that use the include directive from within a function to include source code This is due to the Omniscient Code Generation in the XC8 compiler which can make multiple source files appear in the one COF output It
43. ot being automatically assigned the value 0 by the compiler These objects had no memory reserved for them at all and this may have resulted in them appearing to over lap with other const objects This is now corrected any const object that does not have an initial value is implicitly assigned 0 by the compiler Assertion failure reserving RAM XC8 662 In some instances reserving RAM when using any non enhanced mid range part using the RAM option would result in an assertion fail ure hi gt lo Integers allowed with specifiers XC8 549 The integer constants usable with specifiers such as __at were limited to 16 bit values These values can now be specified as 32 bit values Multiply defined symbols XC8 516 If code used the section specifier with variables there may have been symbols contained in the runtime startup code that were defined more than once producing an error Such symbols might be clear _ramor clrloop for exam ple This duplication has been corrected __mediumconst symbol undefined XC8 621 In some circumstances particularly when using the peripheral library the compiler may have produced an undefined symbol error for __mediumconst Functions not inlined XC8 521 When a function qualified as inline was called from main it was never inlined and a regular call was made Inlining should now take placed for any suitably qualified function called from main Incorrect return instruction XC8 525 For some basel
44. propagation optimizations may affect which variables are watchable in the IDE or the values that are indicated in the Watch window e In line C functions will not be debuggable e Procedural abstraction will affect the operation of breakpoints e Variables residing in both memory and registers may not be correctly displayed in the Watch window e Nested pointers may not be dereferenced correctly in the watch window hence the values in reported in the Watch window will therefore be erroneous e Variables located in external memory will not be displayed correctly in the Watch window e In the Watch window the type name as opposed to the object s name that appears for a anonymous structure or union typedef or an enumerated typedef will be e In the Watch window the type name displayed for an identifier that was declared using a typedef type will be the identifier s semantic type rather than its typedef type Use of __ section specifier If you use the section specifier when defining an object you must also use the same specifier with any declaration of the same object Failure to do so may result in the specifier being ignored Support for scanf functions The compiler does not directly support any of the scanf family functions such as scanf sscanf vscanf etc and they are not compiled into the library files Example source code for some of these functions can be found in the compiler s sources directory These examples have not been
45. r order This write order is not guaranteed for other expressions Watchdog configuration bit Some devices have had their configuration bit setting change from WDTEN to WDT For these devices you will need to update any pragma config directives that specify this setting Implicit function in lining The implicit in lining of function performed as an assembler optimi zation is now disabled by default The assembler optimizer has in the past in lined small assembly routines as part of its optimizations You can re enable it using the driver option MPLAB XC8 C Compiler Version 1 20 Release Notes 9 A auto_ inline This change does not affect in lining of C functions controlled using the inline specifier 4 3 Version 1 11 Inline SFR names When referencing SFR names specified in lt xc h gt from in line assembly code do not use a leading underscore character with the symbol So for example use the symbols PORTA or RAO bit in in line assembly code The same is true for SFR symbols in assembly modules that include lt xc inc gt however the bit symbols have different names for example PORTA and RAO See the user s guide for more information on assem bly code and accessing SFRs Compiler banner information The information shown in the compiler banner printed with each compilation has changed The compiler operating mode is no longer printed but you can still find this information in the list file The license manage will no
46. r Version 1 20 Release Notes 12 Assertion failure using ROM or RAM options XC8 517 When attempting to reserving memory that was outside your target device s on chip memory these options may have caused an assertion failure Invalid access via pointer XC8 643 In some situations the compiler was not detecting that the upper TBLPTR register was being changed from its assumed state As a result code that dereferenced a pointer with both RAM and ROM targets may have corrupted this reg ister and triggered a subsequent failure in the code Assembler crash with bad options XC8 510 If options were passed directly to the assembler application but no file names were present the assembler issued an error and continued processing The error produced in this situation is now a fatal error to prevent the crash This issue would have only affected users driving the assembler directly Assembler crash when specifying functions as inline XC8 589 In some instances when a function was declared inline the assembler crashed Can t Generate Code message associated with unused objects XC8 636 In cases where a pointer was not used but was assigned the address of an object this message may have been emitted Optimizations associated with such code are now restricted and the message will not be issued Parser crash with enumerated types XC8 637 The parser may have crashed when scanning code associated with enumerated types This may have been associ
47. re new features the compiler now supports The version number in the subhead ings indicates the first compiler version to support the features that follow 3 1 Version 1 20 New Device Support The following parts are now fully supported by this release PIC16F1704 PIC16LF1704 PIC16F1708 and PICI6LF1708 ELF DWAREF Debugging Previously COFF debug files were produced to allow source level debugging in MPLAB IDE The compiler can now produce ELF DWARF files although MPLAB XC8 C Compiler Version 1 20 Release Notes 5 the default output format is still COFF ELF DWARF files are not compatible with MPLAB IDE v8 but will be the preferred format if you are using MPLAB X IDE as they have fewer limitations You must be using a version of MPLAB X IDE that supports this file format for the MPLAB XC8 compiler Not all aspects of DWARF are implemented in this compiler release See the Known Issues section for more details New Free mode optimizations The assembler s jump to jump optimizations which previously was only available with a licensed compiler operating mode is now available in Free mode By default this optimization is disabled but it can be enabled from the OPT op tion or the Optimization category in MPLAB X IDE in the usual way If enabled this op timization reduced the size of code output by the compiler New language extension option A new driver option EXT can be set to cci iar or xc8 to indicate that the C language ext
48. rrupt code Psect pragma and data psects As described in the manual the pragma psect directive should not be used to move initialized variables that would normally be located in one of the data psects The initial values in program memory and space for the variables them selves in RAM must be built up in a strict order Using this pragma will violate this as sumption Consider using the _ section specifier In line assembly and labels Functions which are called from both main line and interrupt code should not contain in line assembly that defines assembly labels Such labels will not be assigned the usual duplication prefix i1 i2 etc and will result in multiply defined sym bol errors Bank qualifiers Only bankx qualifiers for data banks 0 through 3 are supported by the compiler These are enabled using the ADDRQUAL option Use absolute variables to place objects in other banks if required MPLAB XC8 C Compiler Version 1 20 Release Notes 26 Memory Report for Absolute Variables If the user defines absolute variables variables placed at an absolute address via the construct and any of these variables overlap other vari ables in memory the compiler will also count overlapping variables when it comes to re porting on memory usage That is if two byte sized variables are located at the same ad dress the report will indicate 2 bytes being used rather than 1 Out of bound variables in watch view If variables are defin
49. s from non OCG compilers as they are not compatible to OCG compil ers and will not compile Undefined Fake symbol PICC 589 PICC 581 This error may have occurred for code that indirectly called a external function defined in assembly code or was part of another build Only functions that returned a value in memory would be affected by this issue The error is no longer produce but you are required to define a symbol that represents the memory MPLAB XC8 C Compiler Version 1 20 Release Notes 21 location where the return value will be stored See the User s Guide on External Functions for more information Linker crash with assembler optimizers PICC 648 If the assembler optimizers psect merg ing were enabled in some situations the linker would crash if a psect was removed but was still referenced by a directive This has been corrected and all assembly optimizations may be employed Compiler crash with bad memory ranges PICC 608 If a memory range was specified using the RAM option or its equivalent in MPLAB IDE and that range was excessively large the compiler my have produced an assertion failure In such situations the compiler now prints a more informative error Cromwell error with MCPxxxx targets PICC 642 If compiling for an MCP device an error relating to the prefix list would have been triggered This has been corrected and compi lation can be performed for these devices Cromwell crash PICC 493 Cromwell may
50. se functions are indirect function calls made via a pointer the compiler will actually encode them using a regular call instruction and when these calls return the stack will overflow The managed stack works as expected for all direct function calls and for all indirect calls that do not exceed the stack depth Main function size If the function main produces assembly code that is 0x1 FF words long this cannot be placed in the program memory and a can t find space error message is pro duced Increasing or decreasing the size of the function will allow it to be positioned cor rectly and the error will not be displayed This only affects Baseline PIC devices Functions called from in line assembly The code generator will not be able to identify a C function called only from in line assembly code if the definition for that C function is placed before the assembly call instruction in the source file Placing the function defini tion after the call is acceptable If the function cannot be identified no code will be gener ated for the function and the linker will issue undefined symbol errors Can t Generate Code messages When compiling for baseline devices some complex expres sions may cause compile time errors 712 Can t generate code for this expression The ex pressions should be simplified to work around this This may require the use of additional variables to store intermediate results This is most likely with long integer or floati
51. t having to reinstall the compiler Run the command regsvr32 C Path_to microchip xc8 v1 10 bin MPLABXC8 d11 for example replacing the path with that appropriate for your compiler installation Call to empty function after comparison XC8 398 Code which calls a function containing no statements an empty definition which is preceded by an if statement may fail for 16F1xxx parts If the assembler optimizer is enabled the call to the empty function or sub sequent code may fail Adding any code such as NOP to the empty function is enough to work around this issue Assignment to pointer member of a union XC8 341 For PIC18 devices and when the com piler is operating in PRO mode assignment of an address to a pointer that is a member of a MPLAB XC8 C Compiler Version 1 20 Release Notes 25 union which in turn is part of a structure may fail if the member is accessed via structure pointer a in the following example strPtr gt myStruct myUnion myPtr mySrcPtr Functions returning pointers XC8 344 If a function returns a pointer the size of this pointer is larger than 1 byte and also larger than the total size of all the parameters passed to this function then the memory used by the return value may not be allocated The function s return value may overwrite other local variables and lead to code failure Consider adding a dummy parameter to the function with the same size as the return value type PIC12F529T39A T48A me
52. t enable bits before execution of a TBLWT instruction 32 FW4000 RESETRAM FETCH CLOCKS W Self write operations initiated from and acting upon a range within the same side of the 4000h boundary may fail based on sequences of in structions executed following the write Data in a RAM location can become corrupted if an asyn chronous reset e g WDT MCLR event occurs during a write operation to that loca tion Instruction fetches can be come corrupted after certain code sequences An instruction may be cor rupted when switching from INTOSC to an external clock source Enhanced mid range devices MPLAB XC8 C Compiler Version 1 20 Release Notes No workaround applied A warning will be issued if the length nvram psect is greater than zero bytes per sistent variables populate this psect A NOP instruction as added after TBLRD instructions returns destinations of calls and gotos and ISR vector addresses Switch to high power mode immediately after reset 33
53. t parameter but the function is never called a bad call to typeSub error may oc cur MPLAB XC8 C Compiler Version 1 20 Release Notes 19 Incorrect optimizations involving carry bit XC8 77 The assembly optimizer may have incor rectly moved instructions that set the carry bit above other code that would subsequently clear carry before it was being used Bad optimization of indirect access XC8 95 In some situations expressions with the form ptr ptr op A may fail In particular it is the optimization of assignment operations when the destination is an indirect access which can lead to incorrect results Bad right shift code XC8 105 In some instances for PIC18 targets the code generated for right shift a signed long operand would access the wrong file registers giving an incor rect result Memory reservation using CODEOFFSET XC8 230 This option should have reserved memory in all linker classes associated with program memory It was only reserving this memory from the CODE class but not for other classes that hold const objects This was unlikely to cause issues since const objects are typically not allocated to low address how ever all classes are now adjusted Badly optimized if code XC8 75 The assembler optimizer may have procedurally abstracted code that erroneously contained return style instructions This may have caused code such as if statements to be ignored and fail This has now been corrected Redunda
54. t values of WREG STATUS and BSR The compiler will load FSR registers without using the LFSR instruction Affected library sources em ploy additional NOP instruc tions at pre scribed locations Additional NOP instruction inserted at reset vector if fol lowing instruction is GOTO Compiler avoids generating MOVLB 15 instructions A warning is issued if this in struction is detected 31 EEDATARD EEADR EE LVD FL LVD TBLWTINT The DAW instruction may improperly clear the CARRY bit STATUS lt 0 gt when exe cuted When reading EEPROM the contents of the EEDATA reg ister may become corrupted in the second instruction cy cle after setting the RD bit EECON1 lt 0 gt The result returned from an EEPROM read operation can be corrupted if the RD bit is set immediately following the loading of the EEADR regis ter Writes to EEPROM memory may not succeed if the inter nal voltage reference is not set Writes to program memory may not succeed if the inter nal voltage reference is not set If a peripheral interrupt oc curs during a TBLWT opera tion data can be corrupted MPLAB XC8 C Compiler Version 1 20 Release Notes The compiler is not affected by this issue The EEPROM_READ macro read EEDATA immediately The compiler is not affected by this issue No workaround applied No workaround applied Library routine flash_write will temporarily disable all applicable interrup
55. uming that the intermediate file to have a p1 extension and not obj resulting in the same behavior Crash with compiler domain symbols XC8 18 User define variables and functions should never start with an underscore character as such symbols are in the compiler s domain In appropriate use of these symbols in a program however was leading to a compiler crash The crash no longer will occur however you should continue to avoid using symbols be ginning with an underscore MPLAB X IDE plugin Previously the XC8 MPLAB IDE plugin overwrote the HI TECH Uni versal Plugin such that the universal plugin no longer appeared in the toolsuite list This is no longer the case The XC8 v1 01 installer will install and reinstate both the XC8 and uni versal plugins so that they will both be selectable from the IDE Bad if code XC8 58 In some instances the assembler optimizer would incorrectly move MOVLW instructions which could cause some logical expressions such as those used by if statements to be incorrectly evaluated Not honoring message disable XC8 62 When compiling for PIC10 12 16 targets the assem bler was not honoring the MSGDISABLE option Thus it was impossible to disable warn ing messages produced by this application This issue did not affect other applications or any application when compiling for PIC18 targets Bad call to subtype Error XC8 73 In some instances where a function has a pointer type as its firs
56. verified to work on all devices and should be used with caution Consider modifying this code to suite your application Redirecting bss variables If the pragma psect directive is used to redirect objects that nor mally reside in any of the bss psects the runtime startup code will not be aware of this and MPLAB XC8 C Compiler Version 1 20 Release Notes 24 will clear the memory that the variables would have ordinarily be allocated At such an early stage this should not affect program execution but if all bss objects are redirected an undefined symbol error will occur with PIC18 devices Consider using the _ section specifier No support for vsprintf XC8 425 This function is not supported in the compiler libraries Previous attempts to use it would have resulted in undefined symbol errors This function is now flagged as unsupported and its use will trigger an error to that effect Installer execution On both Mac OS X and Linux it is necessary to run the installer as root or with superuser privileges using sudo for example If the installer is started without supe ruser privileges on Mac OS X it will exit and display an informative message In the same situation on Linux the installer will fail when it attempts to write to directories for which it does not have adequate rights The messages displayed will relate to these access failures For correct operation run the installer via sudo or as the root user on these systems P
57. w return and print the license type Unused symbol inclusion Unused symbols are no longer included in intermediate p code files This should not affect most customers See the What s New section for information on the new PARSER option which allows unused symbols to be included in the final link step Pointer comparison warning Warning number 1413 is positioned at address 0x0 and has had its address taken pointer comparisons may be invalid should now only be issued for symbols that are user defined and not for temporary vari ables such as ROM or RAM Specification of config pragma The arguments to the pragma config can now be quoted You may prefer to quote the setting value pairs to ensure that the preprocessor does not perform substitution of these tokens e g pragma config BOREN OFF 4 4 Version 1 10 Re activation of the compiler As of version 1 10 the license files used by the XC compiler li cense manager are installed in a different location This is automatically handled by the installer however if you plan to use an older license file with v1 10 you will need to re activate the v1 10 XC8 compiler with your activation key before you can use it Previously the installers could find older license files and did not require re activation Re activation will not be necessary in future when updating compiler versions PIC10 12 16 Assembly Header Files The names of some of the assembly header files have chan
58. ways produced You can continue to specify this option in builds but it will be silently ignored C listings disabled by default C listing files are no longer produced by default See the New listing option in New Features entry for more information Space number for EEPROM changed The space number used by psects that hold EEPROM data has changed from 2 to 3 This only affects PIC10 12 16 devices This will not affect most projects but if you see an error indicating memory space redefined 03 02 then look for hand written assembly that defines a psect used to hold EEPROM data and change the space value Warnings for absolute local objects XC8 652 Previously the compiler would silently ignore any local defined inside a function object which the user had attempted to make absolute The compiler will now issue a warning to say that the address specification will be ignored Warnings for qualified local objects XC8 670 Objects which are local to a function includ ing autos and static local objects cannot be qualified as far or near The compiler was not indicating that the specifier was being ignored A warning is now issued for such defi nitions 4 2 Version 1 12 Access of multi byte SFRs When writing literal values to multibyte volatile SFRs the com piler will write high order byte first then the low order byte This conforms to the require ments of some PIC SFRs such as the NCO register which must be written in a particula
59. when compiling for a PIC18F2610 the corresponding family macro de fined is 18F2X1X_ FAMILY_ To determine the family macro relevant to your device turn on verbose compilation and observe the D options passed to the preprocess cpp Alternatively you may look for the FAMILY field in the picc 18 ini file in the compiler s dat directory 2 2 5 Disabling Optimizations The user s guide indicates that the OPT option or the MPLAB X IDE project properties equivalent widget can be used to disable optimizations Note that in order to disable intrinsic features of OCG you must also run the compiler in Free mode Not all OCG features can be dis abled 2 2 6 Fletcher s Algorithm The code for the fletcher 16 bit algorithm indicated in the user s guide contains a return state ment that should not be present The extraneous statement is towards the end of the fletcher16 function and is marked and bolded in the following sumB sumB amp OXFFFF sumB gt gt 16 return sumB lt lt 16 sum remove me sumB lt lt 16 2 3 New Error Warning Messages The following message is not present in the compiler s user s guide 1457 local variable cannot be make absolute Code Generator You cannot specify the address of any local variable whether it be an auto parameter or static local object int pushState int a int cnt _at 0x100 oops you cannot specify an address 3 What s New The following a
60. y also have occurred if reserved keywords were used in place of variables in expressions The crash has been corrected but variable identifiers cannot be reserved keywords Symbol defined more than once for in line assembly PICC 563 If the REPT macro was specified in in line assembly the code generator was generating additional labels multiple MPLAB XC8 C Compiler Version 1 20 Release Notes 23 times This triggered an error indicating the symbol was defined more than once This has been corrected and REPT can safely be used in in line assembly code RAM ranges for 16 L F1507 The RAM ranges available when selecting this device extended further than the physical device implementation This has been corrected 6 Known Issues The following are limitations in the compiler s operation These may be general coding restric tions or deviations from information contained in the user s manual The bracketed label s in the title are that issue s identification in the tracking database This may be of benefit if you need to contact support ELF debugging issues Not all aspects of the ELF DWARF debugging file have been imple mented in this compiler release Only MPLAB X IDE supports ELF but you must ensure that you are using a version of this IDE that can process ELF files produced by the com piler The following are some of the issues that may not work as expected e Unused variables will not be identified in the ELF file e Constant

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MPLAB® XC8 C Compiler Version 1.20 Release Notes - Digi-Key