DPAS.DOC - OoCities
Contents
1. const p pixel red 127 green 127 blue 127 x 100 y 100 2 3 Variables DPas provides the specifier ABSOLUTE and IOPORT for global variables The following ex sample demonstrates ABSOLUTE and IOPORT var screen screenbuffer absolute B8000 var keybcontroller byte ioport 60 Note that IOPORT can only be used with BYTE WORD INTEGER DWORD LONGINT Nevertheless you can still build up record types of these types e g type VGA MISCELLANEOUS REGISTERS record index read write byte end var MISC VGA MISCELLANEOUS REGISTERS IOPORT 3c2 VGA_MISC index 0 Note that neither ABSOLUTE nor IOPORT can be used in combination with strings c 1999 by Dieter Pawelczak Munich 22 The DPas Language 2 4 Pascal Constructs The standard Pascal constructs BEGIN END CASE FOR TO DOWNTO DO IF THEN ELSE REPEAT UNTIL WHILE DO are supported DPas provides the extended pascal constructs ASM END BREAK CONTINUE DEC and INC Additionally under 32 bit DOS the following arrays are defined to access memory and I O ports MEM MEMW MEML and PORT PORTW PORTL Please note that these arrays are treated different to standard arrays as the following example will demonstrate var kMeml array 0 1 of longint absolute 0 meml 1 5 kmeml 1 5 The first memory access2. 20 2 1532 Record Typen anal Mesa 20 2 1 8 TP 21 2 2 nud 21 2 3 hsc e 21 2 4 Pascal 22 2 5 Inline Assembler u ool NONO EM are mater mney 22 2 6 Procedure 7 Function headers ans 22 2 7 System UNIE RE 23 2 8 RUN TIMB LIBRARY retener nist o era i e e bl 24 28 1 Odi rm 24 2 8 2 DOSSJ qup tei scel 24 2 9 Import of Dynamic Link Libraries aan 24 210 CVU IIEZAG OM nee Sr TR TEN 25 ARPES SIONS so 25 2 10 2 Multiplication Division sans E naar 25 2 19 2 C ONS t lt TES CUS oe Er RE qM v UE 25 2 WA Assembler POCCUUMES oit QAM I UI lese ei P RD De MAE IU Ea ii eid 26 SB ciii M 27 3 1 UJ ETC esse 27 c 1999 by Dieter Pawelczak Munich 3 2 EIL ER 27 3 3 Trance La dE 27 3 4 Passed a 21 Dil 29 4 1 SYMONS m A HEN 29 4 2 Po jm 20 4 3 qi tT DEP A EEUU ME 30 4 4 Array P einen 30 4 5 Boolea
3. Note that some functions are handled by the compiler direct ly WRITELN READLN LENGTH Assign Erase Rename Reset opens TEXT fil e for read EXT f ile for write Rewrit opens T Getdir Close Chdir Eof hart move MoveMem fillchar fillmemchar runerror dosmemavail memavail os zeroofs getmem freemem paramstr strupcase IOResult sin COS arctan ln Sq Bi abs Vtrunc round int new dispose c 1999 by Dieter Pawelczak Munich 24 2 8 RUN TIME LIBRARY A quite large run time library comes with DPas 2 8 1 CRT32 GLESGrE gotoxy wherex wherey color delay keypressed readkey getvideomod setvideomod textcolor background 2 8 2 DOS32 gettime loadfile filelength savefile setintvec getenv exec 2 9 Import of Dynamic Link Libraries The DPas Language DPas can add dynamic link libraries to programs or units These libraries are load during the run time In order to know these functions DPas requires an interface defintion The interface definition is similar to a unit it begins with the but can not define variables or code DLL keyword The interface may define types In case of a Pass32 DLL the specifier FAR and ASSEMBLER are required
4. c 1999 by Dieter Pawelczak Munich Optimization 25 2 10 Optimization 2 10 1 Expressions DPAS optimizes expressions from the left Therefore you should write all constants lefthan ded e g 1024 2 1 instead of i 1024 i 2 The first results in a single SHL expression the second in two SHL expressions 2 10 2 Multiplication Division When possible DPas optimizes multiplications A typical Putpixel function like var screen ARRAY 0 199 0 319 of byte absolute A0000 procedure putpixel x y integer c byte begin screen y x c end Is actually optimized to mov eax y lea eax 4 eaxteax shl eax 6 mov esi x lea esi eaxtesi 0a0000 mov al c mov gs esi al Therefore DPas optimizes mul instructions by the faster lea and or shl instruction 2 10 3 Constant Offsets In case an offset for an array expression is constant DPas optimizes the memory access In case of screen 0 10 5 DPas creates the code mov gs 0a000a 5 c 1999 by Dieter Pawelczak Munich 26 The DPas Language 2 10 4 Assembler Procedures DPas uses for all system procedure calls CPU registers for parameter passing In combination with inline assembler you can also create very fast assembler procedures c 1999 by Dieter Pawelczak Munich Primes 3 Examples 3 1 Primes 27 The PRIMES example is a benchmark program for calculating prime numbers It can be com piled with Turbo Pascal or D
5. 0 79 of char var bigfield array 0 10 of field bigfield 5 0 0 0 4 4 Array Depth The array depth is 3 as maximum a 3 dimensional array field can be defined e g console array 0 10 0 24 0 79 of char You can work around this problem by using array types type console type array 0 10 0 24 0 79 of char var console array 0 10 0 24 0 79 of console type Note that DPas expects proper settings of brackets in this example console can be accessed like console 0 24 0 0 0 0 B 4 5 Boolean Expressions For boolean expressions the compiler needs to learn about the expression type before the comparison symbols like lt gt the compiler can not always resolve record or array ty pes in an expression When ever possible a boolean expression should look like CONST EXPRESSION and not EXPRESSION CONST c 1999 by Dieter Pawelczak Munich ELSE END 31 4 6 ELSE END The parser sometimes falls over a missing before ELSE or END Here the parser is often inconsequent sometimes the parser asks for a before ELSE or END sometimes the parser reports an error when there is a 4 7 WITH WITH is not yet supported 4 8 ASM FPU instructions are not yet supported Not all x86 instructions are correctly supported 4 9 Writeln ReadLn Output and input of float numbers are not supported because of section 4 8 on page
6. 32 bit storage LONGINT signed 32 bit storage POINTER unsigned 32 bit address storage SINGLE 32 bit IEEE float FLOAT 32 bit IEEE float DOUBLE 64 bit IEEE float BOOLEAN TRUE FALSE 8 bit storage TEXT 32 bit file descriptor STRING 256 byte long zero terminated string a for TP compatibility may be extended to 64 bit in future b for TP compatibility there is no FPU emulation The operator is a standard operator in DPas which defines a pointer of the specified type Therefore the operator can be used with any type in any procedure function definition The following parameter definition PROCEDURE A P STRING is as valid as a function like FUNCTION longstr STRING begin getmem longstr 1024 end c 1999 by Dieter Pawelczak Munich 20 The DPas Language 2 1 2 Strings Strings are zero terminated in DPas Per default DPas reserves 256 bytes for a string In case less or more bytes are required a string can also be defined like var small str string 10 Please note that there is no range checking for strings The difference to Turbo Pascal is that string 0 is not the length it represents actually the first letter of the string As strings handled by the system unit and not directly by the compiler the ABSOLUTE spe cifier can not be used in combination with strings 2 1 3 Enumeration Types Enumeration types are treated like integer constants Therefore the following defin
7. DPas is an ongoing development In brief this is planned for the near future Win32 support DPas is able to compiler Pass32 DPas is able to compile itself Contents Abg t ee M nM D Ld EUM 4 Contents E M 5 on ecc e DM D P 7 1 Getting Started with 9 1 1 Kirst Examples doom aue Mando Gets dade asda de maaan SR ASA E 9 1 2 Compiling wat ID Pas 3 2 gs ostenta b Use toos T orit ets 10 1 2 1 Compiling Programs and Units eese eene nnne 10 1 22 Compiling the SYSTEM in dan 11 1 3 The Command Line Arguments oer a 12 1 4 The Standard Program Structures Led ee nde eee Leiden unus 12 1 41 Structure of the Source Code uei ei eie ect ted eder ex kb 12 1 4 2 Structure of the Program Code nn an er ee 14 1 5 The Compiler Direetives aassennsin il 15 1 5 1 Compiler Control Directives eer ee ate ette n ooo Ade or 16 1 5 2 Code Generator Control Directives sn a to die pies 17 2 The DPas ek 19 2 1 ju c c E A 19 2 1 Standard ps 19 2 12 20 2 1 3 Bnumerauon ee 20 Type SUBSHEUDON aon
8. 31 ReadLn and WriteLn does not work with record types or array types e g readLn a 0 4 10 Procedure Function headers The maximum number of parameters is 20 Additional to standard Pascal a function can re turn any type and is not restricted to the standard Pascal types Note that a procedure specifier i e INTERRUPT FAR ASSEMBLER needs to be specified also in any forward definition therefore also in the interface part of a unit 4 11 Sets DPas does not support SET and probably never will 4 12 Error Messages Error messages are not very smart yet c 1999 by Dieter Pawelczak Munich 32 c 1999 by Dieter Pawelczak Munich Limits
9. 4 HELLO3 PAS Now we have the following dependencies HELLO3 gt HUNIT gt CRT32 In order to build the application Example 4 HELLO3 PAS you need to compile DPAS crt32 DPAS hunit DPAS hello3 In case any of these units are already compiled you don t need to re compile of course If you want to change the color of the hello message you can modify CRT32 Now as long as you don t change anything in the procedure interfaces you don t need to re compile HUNIT You modify the implementation of the Writeln procedure in CRT32 for example the you re compile CRT32 and HELLO3 and your modifications will have effect There is one exception in this rule the SYSTEM unit 1 2 2 Compiling the SYSTEM Unit One of the most important features of DPas is that the SYSTEM unit comes with complete source code This makes system specific changes of the compiler very easy The system unit is compiled with the compiler switch SYSTEM The system unit needs to be called SYSTEM PAS for 32 bit DOS Applications and WIN32 PAS for Win32 Applicati Note the SYSTEM unit is the basis for all further units and applications In case you re com piled the SYSTEM unit you need to re compile all units otherwise your application will ter minate with the run time error 0 or create an exception 1 Not supported in DPas Version 1 7 c 1999 by Dieter Pawelczak Munich 12 Getting Started with DPas 1 3 The C
10. DPas you can write SIFDEF DPAS2 Now DPAS CODE SELSE Other compiler e g TP SENDIF c 1999 by Dieter R Pawelczak Munich The Compiler Directives 1 5 2 Code Generator Control Directives Directive Description SM 22 55 S SA LS T Del 5 defines the memory requirements for the program in KByte xx defines the stack size yy the minimum and zz the maximum required memory enables disables I O error checking When enables after each system call the value of IOError is checked When unequal to zero the program aborts with a run time error enables disables stack size checking When enables the program aborts in case the available stack memory is too little enables disables alignment When enabled each data offset is aligned to 4 Note that record types then might not represent the actual intended struc ture c 1999 by Dieter Pawelczak Munich 17 18 c 1999 by Dieter Pawelczak Munich Getting Started with DPas Types 19 2 The DPas Language DPas supports most of standard Pascal and adds some very powerful features mostly derived from C 2 1 Types 2 1 1 Standard Types DPas supports the following standard Pascal types BYTE unsigned 8 bit storage WORD unsigned 16 bit storage DWORD unsigned 32 bit storage INTEGER signed
11. Dieter R Pawelczak DPas32 32 bit Pascal Compiler The DPas User Manual amp Reference Guide Dieter R Pawelczak C 1997 2000 by Dipl Ing Univ Dieter R Pawelczak Fasanenweg 41 D 85540 Haar Germany All rights reserved This manual is sold subject to the condition that it shall not by the way of trade or otherwise be lent re sold hired out or otherwise circulated without the prior written permission of the author No part of this publication may be reproduced or transmitted in any form or by any means electronically optical or mechanically including photocopying recording or any information storage or retrieval system without either the prior written permission of the author or a license from the author permitting restricted copying The author takes no warranty for the examples the manuals the usage and the code generation of DPas32 The software comes without any warranty Windows MS DOS is a trademark of Microsoft Pentium is a trademark of Intel Turbo Pascal TP is a trademark of Borland Inc now Inprise For my dear wife Alexandra About This is the first BETA release of the DPas Compiler The difference between the previous ALPHA releases is huge especially concerning the code generation and optimization DPas is a Pascal Compiler that generates directly executable 32 bit Applications without any further Assembling or Linking The Compiler structure is a direct code generator i e there are
12. Pas In order to be compatible with both compilers DPas defines the compiler define DPAS2 which can be tested with the directive SI 3 2 Direct DEF DPAS2 DIRECT draws a worm on the text screen It uses an ABSOLUTE variable to directly write on the screen It also defines an array type in order to store and restore the screen contents type screen array 0 24 0 79 of word var scr screen absolute B8000 Scrsave screen begin SCrSave sCcr SCr Scrsave j end 3 3 Traffic TRAFFIC is again compatible with TP It defines crazy record types to describe a traffic light simulation The program demonstrates mainly the correct handling of const definitions 3 4 Passed PASSED is next to the Pro32 debugger the largest project created with DPas PASSED is an IDE for the Pass32 compiler PASSED comes together with a simple text window manager PROWIN c 1999 by Dieter Pawelczak Munich 28 c 1999 by Dieter Pawelczak Munich Examples Symbols 20 4 Limits As an ongoing development DPas still has a lot of limits I hope that this chapter will get ob solete in the near future 4 1 Symbols Symbols can not exceed 32 characters A record field can consist of only 28 characters DPas is still a DOS product Therefore it is restricted to 640 K memory DPas can handle about 5000 symbols with 560 KBytes free dos memory This allows to compile Pascal sourc
13. ater in the source ASSEMBLER The procedure is a plain assembler procedure As parame ters CPU registers are used FAR The procedure is a far procedure required to call functions of a Pass32 DLLs The procedure is a Win32 prototype The procedure is a protected mode interrupt a in Version 1 7 not yet supported The main body of a program begins after the first BEGIN command outside a procedure function implementation The main body ends with END followed by a Note there can be no further instructions after END 1 4 2 Structure of the Program Code a Global Structure Every application created with DPas has the same structure c 1999 by Dieter Pawelczak Munich The Compiler Directives 15 00x00100h Program Entry Point jump to the actual start up code 00x00 00x00140h Code and data of the SYSTEM unit 00x02D40hP Code and data of the first unit in the USES list Code and data of the following units Code of the main program Data of the main program Heap memory of the main program a Under the Pro32 Dos Extender the x stands for 0 under Win32 the x stands for 4 b This value depends on the SYSTEM unit version and of course on the DPas Version that compiled the SYSTEM unit DPas initializes all global data i e all your data declarations will be part of the binary For the unit import DPas resolves the dependencies of the units In o
14. ee different ways PROGRAM HELLO VAR c STRING HELLO WO RLD S STRING BEGIN writeln HELLO WORLD writeln c S HELLO WORLD writeln s END Example 1 HELLO PAS The source can be compiled and executed under DOS with DPas hello hello This simple application already describes some of the main functions of the compiler The generated code is linked together with the Pro32 Dos Extender into a standalone applica tion In order to perform the writeln function the Compiler links the SYSTEM unit to the main program Try the same example with the uses instruction The uses instruction im ports and links additional units to the code In case you import the CRT32 unit the standard readin and writeln are overwritten The standard SYSTEM unit uses DOS functions whereas the CRT32 unit access directly the video memory for writeln and the keyboard buffer for readin This allows a much faster output but programs using the CRT32 unit can not redirect the standard input and output PROGRAM HELLO2 USES CRT32 VAR c STRING HELLO WO RLD S STRING BEGIN writeln HELLO WORLD writeln c c 1999 by Dieter Pawelczak Munich 10 Getting Started with DPas S HELLO WORLD writeln s END Example 2 HELLO2 PAS When you run the second example you will notice a lightred output to the screen Lightred is the default color for the CRT32 un
15. entifiers function and procedures which can be linked by other UNITs or PROGRAMs This unit does not contain code it contains only the definition of an external dynamic link library which is load dynamically during the run time The unit may contain enum and record type definitions Directly after the PROGRAM instruction units can be imported with the USES command The USES command is followed by a comma separated list of module names The SYSTEM unit is always linked per default and therefore should not appear on this list The USES com mand needs to come before any code or data definitions Now typically global types variables and sometimes even procedure prototypes are defined In our first example two strings are defined VAR c STRING HELLO WORLD s STRING You already notice a difference to Turbo Pascal global variable definitions can already as sign values to the variables This can either be done with the standard CONST directive or di rectly inside a VAR definition The following examples are valid data definitions VAR Field ARRAY 0 24 0 79 OF WORD 0720 Screen ARRAY 0 24 0 79 OF WORD ABSOLUTE B8000 VAR MaxX MaxY INTEGER 100 I J BYTE TEST BOOLEAN In the first example a two dimensional ARRAY of WORD is generated In the opposite to the CONST definitions you don t have to specify all of the 2000 fields You can define one initial value wh
16. es bet ween 5000 and 32000 lines depending on your style and the complexity of your code As DPas support up to 40 units you can build really huge applications The source code is not restricted in size only the number of symbols Applications can take be up to 64 MByte Note the total limit of symbols is depending from your free DOS memory additionally for each symbol type the following limits are set by DPas Symbol Type Limit Enumeration Type Elememts 800 Integer Constants Record Types Array Types 800 Public Variables 6500 Public Procedures 2000 Lables 6500 4 2 Const There are only two type of constants supported INTEGER e g const Max 10 any type specified constant e g const MaxX INTEGER 10 const Mesg String HELLO const p pixel X 100 Y 100 const cp colorpixel C red P X 100 Y 100 c 1999 by Dieter Pawelczak Munich 30 Limits Not yet supported are string double constants like const Hello Hello const Exact Pi 3 1415 4 3 Types DPas supports all standard Pascal types Note that a record type can consist of a maximum of 100 record fields Arrays can not be combined instead of type field array 0 10 of array 0 24 of array 0 79 of char var bigfield array 0 10 of field bigfield 5 0 0 0 A bigfield 5 0 0 01 write type field array 0 10 0 24
17. ich will be applied for the whole ARRAY In the second line you ll find an ABSOLUTE definition The specifier ABSOLUTE defines that the variable is not part of the program s data segment the variable points to the absolute address as specified In our case the field points to B8000 which is the physical address of the video memory As both arrays are identically you probably know what the first two lines mean Field can be used as a virtual screen and copied to Screen and vice versa c 1999 by Dieter Pawelczak Munich 14 Getting Started with DPas The next example shows the integer definition of MaxX and MaxY both will take the value 100 The next three definitions for I and J will have the init value 0 and FALSE for TEST which are the default A procedure prototype is defined with the PROCEDURE or FUNCTION command PROCEDURE NAME Parameter Parameter Specifier FUNCTION NAME Parameter Parameter Type Specifier A function requires a return type Note that DPas supports any standard Pascal type plus user defined record and enum types as valid return types Even pointers are allowed as return ty pes as the following example shows function longstr string begin getmem longstr 1024 end Please note that this is not allowed in Standard Pascal The specifier for procedures are FORWARD The procedure is defined as a prototype the implementation follows l
18. it You can easily change the value of this color in the CRT32 unit 1 2 Compiling with DPas32 1 2 1 Compiling Programs and Units DPas compiles only one program unit per call DPas does not provide a build feature nor does it check source code dependencies This makes compiling a bit more difficult as with Turbo Pascal for example Nevertheless DPas supports modular programming therefore you just need to re compile the unit that actually changed As long as the interface definition stays compatible you don t need to re compile other units which depend from that modified unit In the case of our simple example HELLO2 the CRT32 unit need to be compiled first DPAS crt32 DPAS hello2 If you want to change the default color in the CRT32 unit you have to recompile the CRT32 unit and of course also your application Imagine a second unit We create a unit HUNIT that simply writes 3 time Hello World and offers a single procedure called WriteHello UNIT HUNIT interface USES Grt32 PROCEDURE WriteHello implementation VAR s string Hello World PROCEDURE WriteHello begin writeln Hello World writeln s s Hello World writeln s c 1999 by Dieter Pawelczak Munich Compiling with DPas32 11 END END Example 3 HUNIT PAS Our third example could then look much easier i e PROGRAM HELLO3 USES hunit BEGIN WriteHello END Example
19. itions are equal type color red green blue is equal to const red 0 green 1 blue 2 type color byte 2 1 4 Type substitution Type substitutions are supported like type shortptr word type color byte 2 1 5 Record Types Record types are supported The number of record fields is limited to 100 type pixel record red green blue byte x y integer end type window record pixels ARRAY 0 10000 OF pixle x y integer title string eng c 1999 by Dieter Pawelczak Munich Const 21 2 1 6 Arrays DPas supports a maximum of three dimensional arrays Array definitions are allowed inside record types constant types and in standard variable definitions e g var board array 0 7 0 7 of char const error mesg array 0 1 of string FILE NOT FOUND ERROR IN FILE ne 2 2 Const DPas allows two kind of constant definitions Initialization inside the VAR block or type spe cified constants inside a CONST block The difference is that an initialization inside the VAR block refers to a whole array or block definition whereas a specified constant type requires values for each element The following example describes the initialization inside the VAR block VAR Field ARRAY 0 24 0 79 OF WORD 0720 VAR MaxX MaxY INTEGER 100 The whole field is filled with the init value 0720 The following example shows a standard definition of specified type constants
20. n EX pressions nu nennen ee tege v getan bos dete scans 30 4 6 EESE SEND ee Gas visa heise EEE einer 31 4 7 IV VEE ik iii Vr Hc D 31 4 8 ASM best 31 4 9 Writeln ReadEn reete bae is pte 31 4 10 Procedure Function headers utu cosas ec OR De 31 galde Lt 31 42 Error Messages nes aan 31 c 1999 by Dieter Pawelczak Munich Introduction What is the DPas32 Compiler The name tells us all Pas stands for Pascal the number 32 informs us that the target platform is 32 bit and the prefix D comes from my surname Therefore DPas can not compile any Pascal it can compile Dieter s Pascal Who uses the DPas32 Compiler Anybody who wants to work under a fast and stable operating system i e 32 bit DOS Pass32 programmers as DPas understands Pass32 DLLs Turbo Pascal programmers who finally made the jump from 16 to 32 bit DPas is a fast 32 bit Pascal Compiler It is compatible in its syntax to Turbo Pascal but it does not provide the same run time library and it does not provide all features of Turbo Pascal It is a Standard Pascal compiler and does not provide any object oriented programming methods DPas supports units in the same manner as Turbo Pascal and therefore allows modular programming DPas creates highly optimized code e g DPas provides optimization of constant expressions optimization of boolea
21. n expressions optimization of const field expressions optimization of multiplication divisions optimization of processor instructions What is DPas not DPas is not a Turbo Pascal clone It is of course possible to port Turbo Pascal programs to DPas programms but the effort varies a lot depending on the source DPas is not a commercial product It is an ongoing development of 1 private person i e me Therefore I can not make any guarantees for bug fixes upgrades etc I also can not give support on DPas except you pay me on the basis of a really high german politician s salary Nevertheless I use DPas for several projects for myself so it is in my interest also to increase the quality of the product Who should read this manual This manual is not a Pascal tutorial you can find already enough of these in the World Wide Web This manual gives an introduction on how to use DPas It describes the features of DPas as well as its limits always in comparison to Turbo Pascal In the meantime you learn something about compiler programming and protected mode programming So this manual is not only for a DPas user it is also interesting for any protected mode and compiler programmer First Example 9 1 Getting Started with DPas 1 1 First Example Any reader is used to the standard Hello World example Therefore you should not miss it in this manual The first example prints three times Hello World in thr
22. no stages between parsing scanning and code generation This makes the source code of the compiler on the one hand very tough on the other hand it provides a lot of advantages The main advantage was that even with only a very little functionality the compiler already created executable code That s why I already published a preliminary Alpha Version in 1997 This release was just able to understand integer expressions and most standard Pascal commands with a lot of limitations Nevertheless with a bit luck I managed to code the Pro 32 debugger already with this initial release Another advantages is that the compiler requires a minimum of heap memory Without building a real command tree the compiler saves a lot of memory As DPas is a DOS product written with Turbo Pascal this is very important The compiler needs only memory to store the symbol names So any source is only limited by the number of symbols And last but not least the compiler is very fast Again for the same reasons During the parsing of the source the compiler already creates code In the mean time the compiler creates highly optimized code This makes the compiler source code very complex as each optimization depends on previous read code and following code Especially hard is of course the error tracing As for each optimization a corresponding test program needs to be written this is an immense effort Therefore DPas will remain for quite some time a BETA version
23. ommand Line Arguments DPas expects the following syntax dpas filename ext options As default DPas extends the filename with the PAS extension The file should be a stan dard ASCII pascal program unit or DLL source DPas provides the following options skips the linking of the PE Header Pro32 dos extender The result is a binary file that contains code and data starting at an offest 0100h target is a Win32 GUI application target is a Win32 Console application adds debug information of units The units need to be compiled with the df option creates debug information of the current source DPas creates a DMP file which can be read by the Pro32 Debugger in order to display the source code allows DPas to compiler the system unit defines the minimum memory require ment in KBytes a not yet supported by V1 7 1 4 The Standard Program Structure 1 41 Structure of the Source Code A standard DPas program begins with the PROGRAM instruction This first keyword PRO GRAM describes what the compiler should create Per default DPas creates an application Therefore the PROGRAM instruction is optional Instead of PROGRAM a DPas source could start with the keywords UNIT and DLL c 1999 by Dieter Pawelczak Munich The Standard Program Structure 13 The following source code defines a standalone appli PROGRAM i cation default The source describes a UNIT i e a set of id
24. ur Example 4 HELLO3 PAS the unit CRT32 is used by HUNIT Therefore DPas will import the units in the following order SYSTEM CRT32 HUNIT In case the user adds CRT32 to the uses sec tion of Example 4 HELLO3 PAS there would be no difference USES hunit crt32 or USES crt32 hunit b Start Up Code The start up code is created when DPas parses the main body i e the main BEGIN instruc tion The start up code will create a stack frame and then call each main function of each unit Note independent on the number of includes of a unit each main function of a unit is called only once The main procedure is called last Start up code is only added to the main program and not to units 1 5 The Compiler Directives DPas supports similar to Turbo Pascal compiler directives The main difference is that com bination of multiple directives is not allowed c 1999 by Dieter Pawelczak Munich 16 Getting Started with DPas 1 5 1 Compiler Control Directives SDEFINE Name INE Name defines a conditional define a conditional define SIFDEF Name The following code is compiled in case Name has been defined SENDIE End of End of conditional block block Ss Alternative block that is EE in case Name has not been defined undefines a conditional define Note that DPas defines always the conditional define DPAS2 To verify whether the source is compiled by
25. will write the longint number 5 at the address 1 the second will wri te the longint number 5 at the address 4 because the array element size is 4 2 5 Inline Assembler Between ASM and END the source code can contain assembler instructions Inside the assem bler instructions global and local variables can be accessed The EBP ESP register need to preserved inside the assembler block 2 6 Procedure Function headers The maximum number of parameters is 20 Additional to standard Pascal a function can re turn any type and is not restricted to the standard Pascal types Note that a procedure specifier i e INTERRUPT FAR ASSEMBLER needs to be specified also in any forward definition therefore also in the interface part of a unit An assembler procedure uses CPU registers as parameters Additionally to the register the type needs to be defined VAR REG8 REG16 REG32 TYPE An assembler functions returns its result in EAX ST 0 for single double types In case the type does not fit into EAX e g strings record types in EAX a pointer to the buffer is retur ned This allows string functions to return in EAX a pointer to the actual string See for ex ample the ParamStr function in SYSTEM PAS c 1999 by Dieter Pawelczak Munich System Unit 2 7 System Unit 23 A lot of standard functions esp the handling of TEXT files are supported Here is an over view of the supported functions
Download Pdf Manuals
Related Search