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Annotation of 43BSDTahoe/ucb/pascal/pdx/runtime/frame.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1980 Regents of the University of California.
        !             3:  * All rights reserved.  The Berkeley software License Agreement
        !             4:  * specifies the terms and conditions for redistribution.
        !             5:  */
        !             6: 
        !             7: #ifndef lint
        !             8: static char sccsid[] = "@(#)frame.c    5.2 (Berkeley) 4/7/87";
        !             9: #endif not lint
        !            10: 
        !            11: /*
        !            12:  * Activation record handling.
        !            13:  *
        !            14:  * The routines curframe and nextframe cheat by using a global copy
        !            15:  * of the display.  This means there can't be multiple instances of
        !            16:  * them active at the same time and nextframe won't work in arbitrary cases.
        !            17:  *
        !            18:  * This could be solved by putting the display copy into the FRAME structure,
        !            19:  * but I didn't feel like doing this.  The idea is that they be used
        !            20:  * in looping through all frames, if I had generators I would use them.
        !            21:  */
        !            22: 
        !            23: #include "defs.h"
        !            24: #include "runtime.h"
        !            25: #include "machine.h"
        !            26: #include "process.h"
        !            27: #include "sym.h"
        !            28: #include "object.h"
        !            29: #include "mappings.h"
        !            30: #include "process/pxinfo.h"
        !            31: #include "frame.rep"
        !            32: #include "process/process.rep"
        !            33: 
        !            34: /*
        !            35:  * Return a pointer to the current activation record.
        !            36:  * Return NIL if currently in the main program.
        !            37:  * The storage is static.
        !            38:  */
        !            39: 
        !            40: #define MAXDEPTH 7
        !            41: #define dispblk(dp)            ((dp - DISPLAY) / 2)
        !            42: 
        !            43: LOCAL ADDRESS *display[MAXDEPTH];
        !            44: LOCAL int dispindex;
        !            45: 
        !            46: FRAME *curframe()
        !            47: {
        !            48:        static FRAME frame;
        !            49:        FRAME *frp;
        !            50:        ADDRESS *dp, *disp;
        !            51:        int i;
        !            52: 
        !            53:        frp = &frame;
        !            54:        dp = curdp();
        !            55:        disp = contents(dp);
        !            56:        if (dispblk(dp) <= MAINBLK) {
        !            57:                return NIL;
        !            58:        } else {
        !            59:                getframe(frp, disp);
        !            60:                for (i = 1; i < MAXDEPTH; i++) {
        !            61:                        display[i] = dispval(i);
        !            62:                }
        !            63:                dispindex = dispblk(dp);
        !            64:                return frp;
        !            65:        }
        !            66: }
        !            67: 
        !            68: /*
        !            69:  * Return a pointer to the next activation record up the stack.
        !            70:  * Return NIL if there is none.
        !            71:  * Writes over space pointed to by given argument.
        !            72:  */
        !            73: 
        !            74: FRAME *nextframe(frp)
        !            75: FRAME *frp;
        !            76: {
        !            77:        ADDRESS *fp;
        !            78: 
        !            79:        if (dispblk(frp->save_dp) <= MAINBLK) {
        !            80:                return(NIL);
        !            81:        } else {
        !            82:                display[dispindex] = frp->save_disp;
        !            83:                dispindex = dispblk(frp->save_dp);
        !            84:                fp = display[dispindex];
        !            85:                getframe(frp, fp);
        !            86:                return(frp);
        !            87:        }
        !            88: }
        !            89: 
        !            90: /*
        !            91:  * Return the frame associated with the given function.
        !            92:  */
        !            93: 
        !            94: FRAME *findframe(f)
        !            95: SYM *f;
        !            96: {
        !            97:        static FRAME frame;
        !            98:        FRAME *frp, *prevfrp;
        !            99: 
        !           100:        frame.save_dp = curdp();
        !           101:        frame.save_disp = contents(frame.save_dp);
        !           102:        prevfrp = &frame;
        !           103:        for (frp = curframe(); frp != NIL; frp = nextframe(frp)) {
        !           104:                if (whatblock(entry(frp)) == f) {
        !           105:                        return frp;
        !           106:                }
        !           107:                *prevfrp = *frp;
        !           108:        }
        !           109:        if (f == program) {
        !           110:                return prevfrp;
        !           111:        } else {
        !           112:                return NIL;
        !           113:        }
        !           114: }
        !           115: 
        !           116: /*
        !           117:  * Get the activation record associated with the given display pointer.
        !           118:  */
        !           119: 
        !           120: LOCAL getframe(frp, disp)
        !           121: FRAME *frp;
        !           122: ADDRESS *disp;
        !           123: {
        !           124:        if (disp == NIL) {
        !           125:                panic("bad disp in getframe");
        !           126:        }
        !           127:        dread(frp, disp, sizeof(FRAME));
        !           128:        frp->save_pc -= ENDOFF;
        !           129: }
        !           130: 
        !           131: /*
        !           132:  * Return the address of the display in the px process for the given block.
        !           133:  */
        !           134: 
        !           135: ADDRESS *dispval(b)
        !           136: int b;
        !           137: {
        !           138:        ADDRESS *r;
        !           139: 
        !           140:        dread(&r, (ADDRESS) (DISPLAY + 2*b), sizeof(r));
        !           141:        return r;
        !           142: }
        !           143: 
        !           144: /*
        !           145:  * Return the current display pointer.
        !           146:  */
        !           147: 
        !           148: ADDRESS *curdp()
        !           149: {
        !           150:        ADDRESS *r;
        !           151: 
        !           152:        dread(&r, (ADDRESS) DP, sizeof(r));
        !           153:        return r;
        !           154: }
        !           155: 
        !           156: /*
        !           157:  * Return the contents of the given display pointer.
        !           158:  */
        !           159: 
        !           160: ADDRESS *contents(dp)
        !           161: ADDRESS *dp;
        !           162: {
        !           163:        ADDRESS *r;
        !           164: 
        !           165:        dread(&r, (ADDRESS) dp, sizeof(r));
        !           166:        return r;
        !           167: }
        !           168: 
        !           169: /*
        !           170:  * Return the px stack address associated with a given frame pointer.
        !           171:  * Actually, to confuse the issue we want the stack address of the
        !           172:  * frame one up from the given one.
        !           173:  */
        !           174: 
        !           175: ADDRESS stkaddr(frp, b)
        !           176: FRAME *frp;
        !           177: int b;
        !           178: {
        !           179:        return (ADDRESS) display[b];
        !           180: }

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