357 The Code Editor
Contents
1. as BRA unconditional branch2. A i jsr O53ACa5 gt i 4EAD 853A E move a4 da 2800 10 imovea l sp a4 1 285F 12 iunlk a i 4E5E 14 rts i 4E75 16 ide b 8D Bui LdResource 24 ide w 0000 Pagee SetUndo link a a008 P4E56 GG 4 i movem d5 d7 a2 a4 tsp PASE 0738 EHA Length 4050 Routines In addition to breaking the data up into instructions the Code Editor analyzes the code when it opens it looking for likely procedure boundaries so that it can parse any MacsBug namestrings and extra compiler data that might be appended to routines The Editor marks the starts of the routines with their names and the offset area displays them in red on the left If a routine has no name the disassembler assigns it a default name lt Anon xx gt where each xx is a unique number Sorcery You can configure the Editor to avoid using brackets lt and gt for unnamed routines Search for lt anon in Resorcerer s own string lists and delete the initial lt Ho Ue zyrO Kem rats oonD SetUndo ShowPair SpillPaint SweepBits Resorcerer sorts the names of procedures in the code alphabetically and installs them in the Routines menu s 27 submenus It places any non alphabeticly named routines in the Other submenu You can navigate scroll to any named routine simply by choosing its name from its menu 359 RESORCERER USER MANUAL 360 USING THE Cope EDITOR Asan extension of the Hex Edit
3. THE Cope EDITOR INTRODUCTION This chapter explains the operation of Resorcerer s Code Editor which is an integrated extension to its Hex Editor The Code Editor lets you disassemble code resources containing Motorola 68000 family machine instructions The Editor can disassemble all 68040 instructions including PMMU and FPU co processor instructions This chapter only covers the extensions the Code Editor brings to the Hex Editor so you should also be familiar with the operation of the Hex Editor whose operation is documented in the H ex Editor chapter later in this volume Also this chapter does not attempt to document 68040 assembly language The disassembler s output is based on Motorola s documentation If you are not already familiar with general resource editing see the Editing Resources chapter earlier in the manual Topics COVERED Creating new code resources Opening a code resource e Using the Code Editor e Making patches 357 RESORCERER USER MANUAL 358 CREATING A New Cope RESOURCE Code resources are typically created by the compiler or assembler in an application development environment The Code Editor does not contain an assembler although it can make a few of the most common patches for you OPENING A Cope RESOURCE Standard 68000 application code is compiled and stored in resources of type CODE There are also a variety of other standalone code resource types commonly used in ap
4. al string data in them Both the hex and the character areas of the display draw single characters at a time soif you choose a variable width font the spacing may be uneven If you click on Save amp OK the type style you choose is recorded in Resorcerer s preferences file so that every time you use the Code Editor it displays with your favorite font If you click on OK then the change is only temporary Usinc DEBUGGER ON DATA If you have a debugger installed in your Mac such as MacsBug you can use it to disassemble the code data in case Resorcerer s Code Editor is doing something different Note Your low level debugger s disassembler generally assumes that the code it is disassembling is part of the currently running application in this case Resorcerer Consequently it may provide incorrect disassembly particularly with regards to jump table references 363 RESORCERER USER MANUAL 364 MAKING PATCHES One of the most common uses of a Code Editor is to perform surgery on an existing application you ve built in order to fix or bypass a bug that is causing grief to your user In Resorcerer s own case we have been able to fix about a third of the reported bugs in earlier versions of Resorcerer by providing simple patches for specific CODE resources The Code Editor s Patch menu assists you in making the three most common length preserving patches used to fix certain types of bugs In the first two ca
5. de area displays 3 digit numbers for bytes 5 digit numbers for words and 10 digit numbers for longs 42 2 44 i 46 Bui dResource 0000 i a6 0080 ion a4 isp fonga HE OSSACAS 2 1 a5 d Bui ldRes i FFI ad d Cspo ad a 4E 80 Bui ldk i75 Decimal offsets 1 x Routine relative offsets 2 Use upper case 3 Switch selections Extend from byte count 3E Goto Find Replace 36 Find Nest Difference Format as Data Format as Code Use Debugger on Data THE Hex EDITOR The Line break relative offsets ae menu item in the Hex Editor is goo dv eto n ontu renamed Routine relative offsets pee ered eee in the Code Editor With this option Ce normally on the disassembl er Bre eevee pisdi generates numerical offsetsthat are meee 8 Be Gc AT au relative to the start of each routine e aaa A reset 2058 With this option turned off BOE moveu g000 e6 d disassembled offsets are with respect SAt ee ee to the start of the data although the offset area still marks the starts of routines with a horizontal line above the starting offset In addition lines mark the starts of the actual MacsBug name data at the ends of routines Regardless of this option s setting the Editor displays the current insertion offset or selection bounds just above the data display area in resource relative offsets It is Sometimes more use
6. ful to view instruction formats in binary than hex for instance Motorola s documentation isin binary You can use Resorcerer s Value Converter in the Edit menu to view and edit any selected 8 16 or 32 bit hex value in binary or a variety of other common formats for more information on this see the Value Converter chapter later in the manual MAKING SELECTIONS To select one instruction click on its line in the code area or double click within its hex or text data To select a sequence of instructions click on the first one and drag the mouse or Shift click to extend the selection For the purposes of cutting and pasting you can also click just to the left of any instruction to place a code insertion caret at the start of the instruction without selecting it To select an entire subroutine double click on any instruction in it Note You cannot select portions of an instruction s text disassembly nor can you enter assembly instructions Above the upper left corner of the scrollable area the Editor displays information about the current selection If the selection is empty then it shows you the position as an offset from the beginning of the resource of the blinking insertion caret as well as what routine it is in If the selection range is non empty you can see the range s endpoints again as offsets from the start of the resource data followed by the range length and the routine the selection starts i
7. n 361 RESORCERER USER MANUAL 362 To the right of the data is a scroll bar that lets you position your view to any word offset in the data As you drag the scroll bar s thumb the Code Editor immediately updates the offset and routine containing that offset to give you a better idea of where you re going to scroll to To change the active selection highlight from the code area to the hex area or to the character area use Switch Selection in the Code menu CODE 21 Cursor Editor from Demo Resource If the first instruction of the selection contains a PC relative branch offset the Editor displays a red arrow on the left side of the offset area which extends either forward or backward edu H depending on the sign of the Length 406A offset to the destination instruction You can instantly scroll to one end or the other of the arrow by clicking anywhere on it The arrow adheres to the branch instruction until you select another branch Selection Range 596 596 2 bytes in CursorEditor SCF ma 4A6D E190 n i 4260 E196 59A move 02 18Ca2 gt sp gt i 2F2A 0210 59E ibtst 03 G0CACa2 gt G82A BaG3 i da H REFORMATTING There may be parts of the data that look to the disassembler like code but which are in fact in line non executable data You can override the disassembler s initial decision as to whether a line of data is a
8. n instruction or data using the Format as Code and Format as Data commands in the Code menu Sorcery Many standalone code resources for instance those compiled with THINK C begin with an unconditional branch instruction around a data header area When the disassembler sees the first instruction as an absolute branch it declares the following data as just data instead of disassembling it It begins disassembling again when it reaches the destination of the branch CUTTING COPYING AND PASTING When the active selection highlight is in the text area copying or cutting places only the selected bytes in the clipboard When the active selection highlight is in the hex area the hex digits of the data area are placed in the clipboard THE Hex EDITOR When the active selection is in the code area the Editor puts both the instruction data and their text disassembly into the dipboard You can cut and paste series of instructions this way although in general this is very dangerous and you should not attempt it unless you really know what you are doing In particular you cannot easily change the length of any section of code over which a branch or jump statement extends SETTING THE TEXT STYLE The Set Text Style command in the Resource menu lets you view and edit your code data using any installed font on the Mac This is useful for larger displays where a larger fixed width font is easier on the eyes or for resources with internation
9. or most of the features of the Hex Editor are also available in the Code Editor You can select bytes in either the hex or text data areas enter data search for and replace hex strings etc The rest of this chapter explains the features the Code Editor adds to the Hex Editor VIEWING Options To adjust the widths of the individual display areas click ona vertical divider line and drag it right or left If you have long MacsBug names you may want to slide the first divider the one between the offset area and the code area to the right In the illustrations here we ve done this as well as dragged the second and third divider lines all the way to the right aG SE BLinkOneCurs 0000 a6 0000 ad sp Badd BSSACaS I a6 a000 d5 d a2 a4 Csp BOH8Ca6 a4 BOHCCaG yd de SetUndot A 00 da The window s Grow and Zoom Boxes enlarge all display areas proportionally When working on small displays there may be times when you want to ensure that you can always see all the hex data You can do this by double clicking on either divider line next to the hex data This turns on the hex word wrap feature If the hex data of an instruction wraps subsequent lines in the code area show continuation dots until the next instruction starts The Decimal Offsets command in the Code menu tells the disassembler and the offset display area to produce base 10 numerical output In this mode the co
10. oved topasan at 256E ABAS 18 i moveg oa d7 i TEGO 12 i moved oggE tat az 246E BGE 16 imove l az 0024 00 gt P2D4A FFOC 1A i move a2 1EAE Coa 2B4A E152 1E imowe ad 1EAA CoS gt P2B4C E156 22 imove 00 166043 1EBECaS gt i 2B6C 8816 192 28 imove w OBAC Cab3 da i 362E AHAC 2C icmpi w 2E dA i C40 GOZE 38 i bhi 06F 8 6208 ABEE 34 lea 8786 a1 i 43FA 674 38 iadd w de d peda i 3A adda w ial d w ai D2F1 agag Fa PE Length 406A THE Hex EDITOR Note The Hex Code Editor is a 32 bit Editor and requires a 10 byte overhead per instruction paragraph Thus a 32K code resource with an average of 3 bytes instruction will require about 100K available memory to open plus the resource data a possible backup copy and another 80K or so for the Editor itself All of which adds up to an easy 250K To open multiple or much larger code resources you will likely have to increase Resorcerer s partition size If an instruction appears illegal the disassembler assumes it is actually inline data and breaks it up into the appropriate number of word data declarations It then continues to disassemble at the next instruction i ODE 21 Cursor Editor from Demo Resources Insertion Offset 868 in BuildResource 46 ide Ez EE EEEE Bui lLdResource link a6 og0g 4E5656 sage 4 move a4 isp i 2Fec 6 pea a44 4878 B044
11. plications such as Menu Definition MDEF Procedures Control Definition CDEF Procedures and List Definition _DEF Procedures Resorcerer is shipped with the knowledge of about 50 resource types that contain system or application code These are all declared as synonyms of CODE resources so that the Code Editor will open them automatically for you for more on declaring synonyms see the Synonym Preferences section of the Preferences chapter DISASSEMBLING THE CODE The Code Editor extends the Hex Editor by adding an extra code viewing area to the Hex Editor s standard offset hex and text display areas When the Editor opens the code resource the disassembl er parses the entire resource into individual machine instructions each of which ranges in length from 1 to 11 16 bit words The Hex Editor then inserts a paragraph break at the start of each instruction Unlike the Hex Editor the Code Editor does not mark the paragraph boundaries in the offset area since the code area makes these obvious The code area then disassembles the starts of each paragraph line on the fly as you display different parts of the hex data a CODE 21 Cursor Editor from Demo Resources Insertion Offset 28 in CursorEditor idc w 93BR Jump Table offi 9380 2 idc w oagg dump Table enti g 4 Fi link ab 0040 4E56 FFG 8 movem d3 d az a4 Csp i 48E 1F38 C im
12. ses you should select the instructions that you want to avoid executing and either change them all to NOP instructions which do nothing or change the first few words of the selection into an Patch Set Selection to NOPs Branch around selection Set branch condition to r EQ equal NE not equal GE greater than or equal GT greater than LT less than LE less than or equal HI high LS low or same MI minus PL plus CC carry clear CS carry set UC overflow clear US overflow set absolute branch to the first T always True instruction after the selection SES SSE In the third type of patch you must first select an instruction that uses the condition code bits syntax These are the Bcc DBcc Scc Of TRAP cc instructions where the cc can be any of the condition abbreviations listed in the above menu J ust choose the condition you want the selected instruction to use from the heirarchical submenu of conditions A typical example of how this is useful is when you have discovered in your source code that the condition computed by an if statement should have been gt rather than gt You need first to use your development system debugger or disassembler to help you find the instruction s in the segment CODE resource that correspond to the condition evaluation and change the related branch instruction Note The Bec instruction where the condition ccis T Always True is generally disassembled
Download Pdf Manuals
Related Search