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Annotation of 43BSD/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    5.1 (Berkeley) 6/6/85";
        !             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: 
        !            33: /*
        !            34:  * Return a pointer to the current activation record.
        !            35:  * Return NIL if currently in the main program.
        !            36:  * The storage is static.
        !            37:  */
        !            38: 
        !            39: #define MAXDEPTH 7
        !            40: #define dispblk(dp)            ((dp - DISPLAY) / 2)
        !            41: 
        !            42: LOCAL ADDRESS *display[MAXDEPTH];
        !            43: LOCAL int dispindex;
        !            44: 
        !            45: FRAME *curframe()
        !            46: {
        !            47:        static FRAME frame;
        !            48:        FRAME *frp;
        !            49:        ADDRESS *dp, *disp;
        !            50:        int i;
        !            51: 
        !            52:        frp = &frame;
        !            53:        dp = curdp();
        !            54:        disp = contents(dp);
        !            55:        if (dispblk(dp) <= MAINBLK) {
        !            56:                return NIL;
        !            57:        } else {
        !            58:                getframe(frp, disp);
        !            59:                for (i = 1; i < MAXDEPTH; i++) {
        !            60:                        display[i] = dispval(i);
        !            61:                }
        !            62:                dispindex = dispblk(dp);
        !            63:                return frp;
        !            64:        }
        !            65: }
        !            66: 
        !            67: /*
        !            68:  * Return a pointer to the next activation record up the stack.
        !            69:  * Return NIL if there is none.
        !            70:  * Writes over space pointed to by given argument.
        !            71:  */
        !            72: 
        !            73: FRAME *nextframe(frp)
        !            74: FRAME *frp;
        !            75: {
        !            76:        ADDRESS *fp;
        !            77: 
        !            78:        if (dispblk(frp->save_dp) <= MAINBLK) {
        !            79:                return(NIL);
        !            80:        } else {
        !            81:                display[dispindex] = frp->save_disp;
        !            82:                dispindex = dispblk(frp->save_dp);
        !            83:                fp = display[dispindex];
        !            84:                getframe(frp, fp);
        !            85:                return(frp);
        !            86:        }
        !            87: }
        !            88: 
        !            89: /*
        !            90:  * Return the frame associated with the given function.
        !            91:  */
        !            92: 
        !            93: FRAME *findframe(f)
        !            94: SYM *f;
        !            95: {
        !            96:        static FRAME frame;
        !            97:        FRAME *frp, *prevfrp;
        !            98: 
        !            99:        frame.save_dp = curdp();
        !           100:        frame.save_disp = contents(frame.save_dp);
        !           101:        prevfrp = &frame;
        !           102:        for (frp = curframe(); frp != NIL; frp = nextframe(frp)) {
        !           103:                if (whatblock(entry(frp)) == f) {
        !           104:                        return frp;
        !           105:                }
        !           106:                *prevfrp = *frp;
        !           107:        }
        !           108:        if (f == program) {
        !           109:                return prevfrp;
        !           110:        } else {
        !           111:                return NIL;
        !           112:        }
        !           113: }
        !           114: 
        !           115: /*
        !           116:  * Get the activation record associated with the given display pointer.
        !           117:  */
        !           118: 
        !           119: LOCAL getframe(frp, disp)
        !           120: FRAME *frp;
        !           121: ADDRESS *disp;
        !           122: {
        !           123:        if (disp == NIL) {
        !           124:                panic("bad disp in getframe");
        !           125:        }
        !           126:        dread(frp, disp, sizeof(FRAME));
        !           127:        frp->save_pc -= ENDOFF;
        !           128: }
        !           129: 
        !           130: /*
        !           131:  * Return the address of the display in the px process for the given block.
        !           132:  */
        !           133: 
        !           134: ADDRESS *dispval(b)
        !           135: int b;
        !           136: {
        !           137:        ADDRESS *r;
        !           138: 
        !           139:        dread(&r, (ADDRESS) (DISPLAY + 2*b), sizeof(r));
        !           140:        return r;
        !           141: }
        !           142: 
        !           143: /*
        !           144:  * Return the current display pointer.
        !           145:  */
        !           146: 
        !           147: ADDRESS *curdp()
        !           148: {
        !           149:        ADDRESS *r;
        !           150: 
        !           151:        dread(&r, (ADDRESS) DP, sizeof(r));
        !           152:        return r;
        !           153: }
        !           154: 
        !           155: /*
        !           156:  * Return the contents of the given display pointer.
        !           157:  */
        !           158: 
        !           159: ADDRESS *contents(dp)
        !           160: ADDRESS *dp;
        !           161: {
        !           162:        ADDRESS *r;
        !           163: 
        !           164:        dread(&r, (ADDRESS) dp, sizeof(r));
        !           165:        return r;
        !           166: }
        !           167: 
        !           168: /*
        !           169:  * Return the px stack address associated with a given frame pointer.
        !           170:  * Actually, to confuse the issue we want the stack address of the
        !           171:  * frame one up from the given one.
        !           172:  */
        !           173: 
        !           174: ADDRESS stkaddr(frp, b)
        !           175: FRAME *frp;
        !           176: int b;
        !           177: {
        !           178:        return (ADDRESS) display[b];
        !           179: }

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