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Annotation of 42BSD/ucb/pascal/pdx/runtime/frame.c, revision 1.1

1.1     ! root        1: /* Copyright (c) 1982 Regents of the University of California */
        !             2: 
        !             3: static char sccsid[] = "@(#)frame.c 1.1 1/18/82";
        !             4: 
        !             5: /*
        !             6:  * Activation record handling.
        !             7:  *
        !             8:  * The routines curframe and nextframe cheat by using a global copy
        !             9:  * of the display.  This means there can't be multiple instances of
        !            10:  * them active at the same time and nextframe won't work in arbitrary cases.
        !            11:  *
        !            12:  * This could be solved by putting the display copy into the FRAME structure,
        !            13:  * but I didn't feel like doing this.  The idea is that they be used
        !            14:  * in looping through all frames, if I had generators I would use them.
        !            15:  */
        !            16: 
        !            17: #include "defs.h"
        !            18: #include "runtime.h"
        !            19: #include "machine.h"
        !            20: #include "process.h"
        !            21: #include "sym.h"
        !            22: #include "object.h"
        !            23: #include "mappings.h"
        !            24: #include "process/pxinfo.h"
        !            25: #include "frame.rep"
        !            26: 
        !            27: /*
        !            28:  * Return a pointer to the current activation record.
        !            29:  * Return NIL if currently in the main program.
        !            30:  * The storage is static.
        !            31:  */
        !            32: 
        !            33: #define MAXDEPTH 7
        !            34: #define dispblk(dp)            ((dp - DISPLAY) / 2)
        !            35: 
        !            36: LOCAL ADDRESS *display[MAXDEPTH];
        !            37: LOCAL int dispindex;
        !            38: 
        !            39: FRAME *curframe()
        !            40: {
        !            41:        static FRAME frame;
        !            42:        FRAME *frp;
        !            43:        ADDRESS *dp, *disp;
        !            44:        int i;
        !            45: 
        !            46:        frp = &frame;
        !            47:        dp = curdp();
        !            48:        disp = contents(dp);
        !            49:        if (dispblk(dp) <= MAINBLK) {
        !            50:                return NIL;
        !            51:        } else {
        !            52:                getframe(frp, disp);
        !            53:                for (i = 1; i < MAXDEPTH; i++) {
        !            54:                        display[i] = dispval(i);
        !            55:                }
        !            56:                dispindex = dispblk(dp);
        !            57:                return frp;
        !            58:        }
        !            59: }
        !            60: 
        !            61: /*
        !            62:  * Return a pointer to the next activation record up the stack.
        !            63:  * Return NIL if there is none.
        !            64:  * Writes over space pointed to by given argument.
        !            65:  */
        !            66: 
        !            67: FRAME *nextframe(frp)
        !            68: FRAME *frp;
        !            69: {
        !            70:        ADDRESS *fp;
        !            71: 
        !            72:        if (dispblk(frp->save_dp) <= MAINBLK) {
        !            73:                return(NIL);
        !            74:        } else {
        !            75:                display[dispindex] = frp->save_disp;
        !            76:                dispindex = dispblk(frp->save_dp);
        !            77:                fp = display[dispindex];
        !            78:                getframe(frp, fp);
        !            79:                return(frp);
        !            80:        }
        !            81: }
        !            82: 
        !            83: /*
        !            84:  * Return the frame associated with the given function.
        !            85:  */
        !            86: 
        !            87: FRAME *findframe(f)
        !            88: SYM *f;
        !            89: {
        !            90:        static FRAME frame;
        !            91:        FRAME *frp, *prevfrp;
        !            92: 
        !            93:        frame.save_dp = curdp();
        !            94:        frame.save_disp = contents(frame.save_dp);
        !            95:        prevfrp = &frame;
        !            96:        for (frp = curframe(); frp != NIL; frp = nextframe(frp)) {
        !            97:                if (whatblock(entry(frp)) == f) {
        !            98:                        return frp;
        !            99:                }
        !           100:                *prevfrp = *frp;
        !           101:        }
        !           102:        if (f == program) {
        !           103:                return prevfrp;
        !           104:        } else {
        !           105:                return NIL;
        !           106:        }
        !           107: }
        !           108: 
        !           109: /*
        !           110:  * Get the activation record associated with the given display pointer.
        !           111:  */
        !           112: 
        !           113: LOCAL getframe(frp, disp)
        !           114: FRAME *frp;
        !           115: ADDRESS *disp;
        !           116: {
        !           117:        if (disp == NIL) {
        !           118:                panic("bad disp in getframe");
        !           119:        }
        !           120:        dread(frp, disp, sizeof(FRAME));
        !           121:        frp->save_pc -= ENDOFF;
        !           122: }
        !           123: 
        !           124: /*
        !           125:  * Return the address of the display in the px process for the given block.
        !           126:  */
        !           127: 
        !           128: ADDRESS *dispval(b)
        !           129: int b;
        !           130: {
        !           131:        ADDRESS *r;
        !           132: 
        !           133:        dread(&r, (ADDRESS) (DISPLAY + 2*b), sizeof(r));
        !           134:        return r;
        !           135: }
        !           136: 
        !           137: /*
        !           138:  * Return the current display pointer.
        !           139:  */
        !           140: 
        !           141: ADDRESS *curdp()
        !           142: {
        !           143:        ADDRESS *r;
        !           144: 
        !           145:        dread(&r, (ADDRESS) DP, sizeof(r));
        !           146:        return r;
        !           147: }
        !           148: 
        !           149: /*
        !           150:  * Return the contents of the given display pointer.
        !           151:  */
        !           152: 
        !           153: ADDRESS *contents(dp)
        !           154: ADDRESS *dp;
        !           155: {
        !           156:        ADDRESS *r;
        !           157: 
        !           158:        dread(&r, (ADDRESS) dp, sizeof(r));
        !           159:        return r;
        !           160: }
        !           161: 
        !           162: /*
        !           163:  * Return the px stack address associated with a given frame pointer.
        !           164:  * Actually, to confuse the issue we want the stack address of the
        !           165:  * frame one up from the given one.
        !           166:  */
        !           167: 
        !           168: ADDRESS stkaddr(frp, b)
        !           169: FRAME *frp;
        !           170: int b;
        !           171: {
        !           172:        return (ADDRESS) display[b];
        !           173: }

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