Developer CD Series 1991 July: Desperately Seeking Seven

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/ Developer CD Series 1991 …esperately Seeking Seven / Desperately Seeking Seven.2mg / Dev.CD.8 / Essentials / Tools / DTS.Samples / SC20DTSToolLib / PtrCheck.asm < prev next >

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Assembly Source File | 1990-04-06 | 11.0 KB | 379 lines | [04] ASCII Text (0x0000)

****************************************************************************** * * lclptr.checker * * Copyright (C) 1989 by Apple Computer. * Written by Eric Soldan. * * Converted to APW 6-May-90 DAL * ****************************************************************************** case on rtlStkDepth gequ 50 ;You may need to make this bigger. ****************************************************************************** * * These functions are to help detect usage of C pointers and handles that are * not initialized. In main(), call initPtrCheck(). Do NOT call other * functions in main. * * In other functions, call zapLocals() as the first thing in the function. * checkForHit() will automatically be called whenever you exit a function. * You can call checkForHit() at any point you want, also. If you have an idea * of which function has a pointer problem, but you are not sure where in * the function the problem is, you can add some calls to checkForHit(). * The functions initPtrCheck(), closePtrCheck(), zapLocals(), and * checkForHit() can be conditionally set active or inactive with #define * statements. This way they can be active when developing, and turned off * when making a production version. The calls can be defined to nothing, * thus making any reference to them drop out of the object code. * * So, a C program would use the functions as below: * * main() * { * initPtrCheck(_ownerid); * /* Your code goes here */ * closePtrCheck(); * exit(0); * } * * void someFnCalledByMain(parm1, parm2) * unsigned int parm1, parm2; * { * unsigned int i, j, k; * unsigned long theID; * * zapLocals(); * /* Your code goes here */ * checkForHit(); * } * * Note that zapLocals() needs to be the first code in a function. Also, * you can't call zapLocals before you call initPtrCheck(). Given this * dependency, you can't call zapLocals in main(). To fix this problem, * you may wish to have a nearly empty main(). You may want it to just * do the initPtrCheck() and closePtrCheck(), and the code in between * simply calls something like main0(), which can have a zapLocals(). * ****************** * The return address to exit zapLocals is used to point to the code used to * create the stack frame. The stack frame code should look like the below. * The values in front are the negative offsets from the return address. * (This is why zapLocals() must be the first code in a function.) * E PHD * D TSC * C SEC * BA9 SBC #$fb * 8 TCD * 765 ADC #$f0 * 4 TCS * * 321.0 JSL >zapLocals ****************************************************************************** mcopy 2/ainclude/m16.memory mcopy 2/ainclude/m16.misctool mcopy 2/ainclude/m16.util2 initPtrCheck start DefineStack hndl long ;Must be at 1,s. ptr long dpage word retaddr block 3 userid word phd pha ;Make space for locals. pha pha pha tsc tcd pea 1 ;Get the bank-sized handle. lda #0 sta >rtlStkPtr ;Nothing on "stack" yet. pha pei userid pea $C010 pha pha _NewHandle bcc gothndl lda #0 sta >ptrCheckHndl ;Flag as no handle. sta >ptrCheckHndl+2 sta >zapval ;"Pattern" is 0. sta >$0 ;Point 0-2 to the screen. lda #$E100 ;If there is any bad stuff sta >$1 ;going on, then it will show bra exit1 ;on the super-hi-res screen. * ;This is true only for handles. * ;Simple pointers will still * ;store into zpage. Storing * ;into zpage will, most likely, * ;cause the system to die. * ;The best test is when the * ;system has enough memory to * ;create the 64k hit-test handle. gothndl lda hndl ;Keep the handle, and initialize it. sta >ptrCheckHndl lda hndl+2 sta >ptrCheckHndl+2 ldy #2 ;Dereference the handle to get to lda [hndl],y ;the bank of memory. sta ptr+2 lda [hndl] sta ptr lda ptr+2 ;Move byte 2 of bank address into xba ;byte 3 also. ora ptr+2 sta >zapval ldy #0 ;Fill the handle with the bank value, loop sta [ptr],y ;so pointers within the handle end iny ;up pointing back into the handle. iny bne loop sta >$0 sta >$2 exit1 pla pla pla pla pld rtl ptrCheckHndl entry dc i4'0' zapval entry dc i2'0' rtlStkPtr entry dc i2'0' rtlStk entry ds rtlStkDepth*3 end ****************** zapLocals start DefineStack ptr long dpage word retaddr block 3 phd pha ;Make space for locals. pha tsc tcd lda retaddr+1 ;Use return address as pointer. sta ptr+1 lda retaddr sec sbc #$0A sta ptr lda [ptr] ;sbc value tax ldy #4 lda [ptr],y ;adc value sta ptr txa sec sbc ptr beq exit2 ;No stack frame at all. tax ;Save this to fetch RTL address. tay ;Number of bytes to zap. dey beq exit2 ;Just in case. tsc clc adc #retaddr+2 ;Point to beginning of stack sta ptr ;frame to clobber. stz ptr+2 shortm lda >zapval ;Pattern to clobber with. loop2 sta [ptr],y dey bne loop2 longm inx ;Save the return address on rtlStk. inx txy ;yreg is offset to return address. lda >rtlStkPtr cmp #rtlStkDepth*3 ;Make sure we aren't overflowing rtlStk. bcc stackOK brk $AA stackOK tax lda [ptr],y sta >rtlStk,x iny inx lda [ptr],y sta >rtlStk,x ;Return address now on rtlStk. inx inx txa sta >rtlStkPtr ;Save new index into rtlStk. lda #rtlCheck|-8 ;Put return address of checking sta [ptr],y ;routine in place of regular dey ;return address. lda #rtlCheck-1 sta [ptr],y exit2 pla pla pld rtl rtlCheck anop ;This is where we end up when a c * ;function exits with an rtl. jsl saveRegs ;Keep registers for return value for c. lda >rtlStkPtr ;Get the real return address onto the stack. tax dex dex lda >rtlStk,x pha ;We pushed middle and hi byte here. phb pla ;We just pulled the middle byte. dex lda >rtlStk,x pha ;We pushed low and middle byte here, so * ;we have a full rtl address on stack. txa sta >rtlStkPtr jml checkForHitz saveRegs entry sta >keepa ;Keep everything. txa sta >keepx tya sta >keepy php php pla sta >keepp rtl getRegs entry lda >keepp pha lda >keepx tax lda >keepy tay lda >keepa plp plp rtl keepa dc i2'0' keepx dc i2'0' keepy dc i2'0' keepp dc i2'0' end ****************** checkForHit start jsl saveRegs checkForHitz entry lda >zapval beq exit3 ;When using zpage as hit * ;detector, there is nothing * ;we can check. We just have * ;to wait until the system * ;dies a horrible death. This * ;horrible death should happen * ;faster when clobbering zpage. tax and #$FFFE ;So we can go by words. tay txa phb pha plb plb loop3 cmp |$0,y bne oops1 iny iny bne loop3 plb ;Put data bank back. exit3 jml getRegs oops1 plb brk $AB ;Bank is indicated by acc. * ;Offset into bank that was hit is * ;in the yreg. * ;The program can be resumed, but unless * ;the hit is repaired, the program will * ;break again. jml getRegs ;Allow option of continuing from debugger. end ****************** closePtrCheck start jsl checkForHit ;Let's make sure there were no hits. lda >zapval beq exit ;No handle to dispose of. lda >ptrCheckHndl+2 pha lda >ptrCheckHndl pha _DisposeHandle ;We got rid of what we created. lda #0 sta >zapval exit rtl end