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Annotation of 43BSD/ucb/lisp/franz/68k/nargs.c, revision 1.1

1.1     ! root        1: /* Copyright (c) 1982, Regents, University of California */
        !             2: #define ADDQ 5
        !             3: #define ADD 13
        !             4: #define IMMED 074
        !             5: /* These structures are here for looks, only */
        !             6: struct add { short op:4, reg:3, mode:3, ea:6; } x;
        !             7: struct addq { short op:4, data:3, size:3, ea:6; } y;
        !             8: nargs(arg)
        !             9: long arg; /* this is only here for address calculation */
        !            10: {
        !            11:        register long *a5;
        !            12:        register handy;
        !            13:        register char reg, mode, ea;
        !            14: #define size mode
        !            15: #define data reg
        !            16: 
        !            17:        a5 = (&arg) - 2; /* this points to old a6 */
        !            18:        a5 = (long *) *a5; /* a5 now = my parents a6 */
        !            19:        a5 = (long *) a5[1]; /* pick up return address into a5 */
        !            20: 
        !            21:        handy = * (short *)a5;
        !            22:        ea = handy & 077; handy >>= 6;
        !            23:        mode = handy & 07; handy >>= 3;
        !            24:        reg = handy & 07; handy >>= 3;
        !            25:        /* op = handy & 017; */
        !            26:        switch(handy & 017) {
        !            27:        case ADD:
        !            28:                if(reg!=7)
        !            29:                        return(0); /* this instruction doesn't adjust the sp */
        !            30:                if(ea!=IMMED)
        !            31:                        return(0); /* too hard to decode adjustment */
        !            32:                handy = (long) (1 + (short *) a5);
        !            33:                if(mode==03) {  /* addw #n,a7 */
        !            34:                        handy = *(short *)handy;
        !            35:                        return(handy >> 2);
        !            36:                }
        !            37:                if(mode==07) { /* addl #n,a7 */
        !            38:                        handy = *(long *)handy;
        !            39:                        return(handy >> 2);
        !            40:                }
        !            41:                else return(0); /* this was doing something to d7 */
        !            42:        case ADDQ:
        !            43:                if(ea!=017)
        !            44:                        return(0); /* this doesn't adjust a7 */
        !            45:                if(size!=02)
        !            46:                        return(0); /* should complain -- we are doing
        !            47:                                      addq[bw] something,a7 */
        !            48:                switch(data) {
        !            49:                case 0: return(2);
        !            50:                case 4: return(1);
        !            51:                }
        !            52:        }
        !            53:        return(0);
        !            54: }

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