139 lines
3.5 KiB
C
139 lines
3.5 KiB
C
/*
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* GSP assembler - expression evaluation
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*
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* Copyright (c) 1993 Paul Mackerras.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Paul Mackerras.
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software withough specific prior written permission
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "gsp_ass.h"
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#include "y.tab.h"
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int32_t eval_op(int, int32_t, int32_t);
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int32_t eval_subtree(expr, unsigned *);
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expr
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fold(register expr x)
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{
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register int32_t l;
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register expr lp, rp;
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switch( x->e_op ){
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case SYM:
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case CONST:
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case '.':
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return x;
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}
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x->e_left = lp = fold(x->e_left);
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if( x->e_right != NULL )
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x->e_right = rp = fold(x->e_right);
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else
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rp = NULL;
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if( lp->e_op == CONST && (rp == NULL || rp->e_op == CONST) ){
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/* operator with constant subtree(s) */
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if( rp != NULL ){
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l = eval_op(x->e_op, lp->e_val, rp->e_val);
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free(rp);
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} else
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l = eval_op(x->e_op, lp->e_val, 0);
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free(lp);
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x->e_op = CONST;
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x->e_val = l;
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}
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return x;
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}
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int32_t
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eval_op(int op, register int32_t l, register int32_t r)
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{
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switch( op ){
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case NEG: l = -l; break;
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case '~': l = ~l; break;
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case '+': l += r; break;
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case '-': l -= r; break;
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case '*': l *= r; break;
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case '&': l &= r; break;
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case '|': l |= r; break;
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case '^': l ^= r; break;
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case '/':
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if( r == 0 )
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perr("Divide by zero");
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else
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l /= r;
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break;
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case ':':
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l = (l << 16) | (r & 0xFFFF);
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break;
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case LEFT_SHIFT:
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l <<= r;
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break;
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case RIGHT_SHIFT:
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l >>= r;
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break;
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}
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return l;
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}
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int
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eval_expr(expr e, int32_t *vp, unsigned *lp)
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{
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e = fold(e);
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*vp = eval_subtree(e, lp);
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return (*lp < NOT_YET);
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}
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int32_t
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eval_subtree(expr e, unsigned *lp)
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{
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register symbol s;
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int32_t v1, v2;
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unsigned l2;
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switch( e->e_op ){
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case SYM:
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s = e->e_sym;
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*lp = s->lineno;
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if( (s->flags & DEFINED) != 0 )
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return s->value;
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perr("Undefined symbol %s", s->name);
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return 0;
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case CONST:
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*lp = 0;
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return e->e_val;
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case '.':
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*lp = lineno;
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return pc;
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default:
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v1 = eval_subtree(e->e_left, lp);
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if( e->e_right == NULL )
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return eval_op(e->e_op, v1, 0);
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v2 = eval_subtree(e->e_right, &l2);
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if( l2 > *lp )
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*lp = l2;
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return eval_op(e->e_op, v1, v2);
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}
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}
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