1 /* $NetBSD: gsp_eval.c,v 1.4 2001/06/13 10:46:06 wiz Exp $ */ 2 /* 3 * GSP assembler - expression evaluation 4 * 5 * Copyright (c) 1993 Paul Mackerras. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by Paul Mackerras. 19 * 4. The name of the author may not be used to endorse or promote products 20 * derived from this software without specific prior written permission 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 #include <sys/cdefs.h> 35 #ifndef lint 36 __RCSID("$NetBSD: gsp_eval.c,v 1.4 2001/06/13 10:46:06 wiz Exp $"); 37 #endif 38 39 #include <stdlib.h> 40 #include "gsp_ass.h" 41 #include "gsp_gram.h" 42 43 int32_t eval_op(int, int32_t, int32_t); 44 int32_t eval_subtree(expr, unsigned *); 45 46 expr 47 fold(expr x) 48 { 49 int32_t l; 50 expr lp, rp; 51 52 switch( x->e_op ){ 53 case SYM: 54 case CONST: 55 case '.': 56 return x; 57 } 58 x->e_left = lp = fold(x->e_left); 59 if( x->e_right != NULL ) 60 x->e_right = rp = fold(x->e_right); 61 else 62 rp = NULL; 63 if( lp->e_op == CONST && (rp == NULL || rp->e_op == CONST) ){ 64 /* operator with constant subtree(s) */ 65 if( rp != NULL ){ 66 l = eval_op(x->e_op, lp->e_val, rp->e_val); 67 free(rp); 68 } else 69 l = eval_op(x->e_op, lp->e_val, 0); 70 free(lp); 71 x->e_op = CONST; 72 x->e_val = l; 73 } 74 return x; 75 } 76 77 int32_t 78 eval_op(int op, int32_t l, int32_t r) 79 { 80 switch( op ){ 81 case NEG: l = -l; break; 82 case '~': l = ~l; break; 83 case '+': l += r; break; 84 case '-': l -= r; break; 85 case '*': l *= r; break; 86 case '&': l &= r; break; 87 case '|': l |= r; break; 88 case '^': l ^= r; break; 89 case '/': 90 if( r == 0 ) 91 perr("Divide by zero"); 92 else 93 l /= r; 94 break; 95 case ':': 96 l = (l << 16) | (r & 0xFFFF); 97 break; 98 case LEFT_SHIFT: 99 l <<= r; 100 break; 101 case RIGHT_SHIFT: 102 l >>= r; 103 break; 104 } 105 return l; 106 } 107 108 int 109 eval_expr(expr e, int32_t *vp, unsigned *lp) 110 { 111 e = fold(e); 112 *vp = eval_subtree(e, lp); 113 return (*lp < NOT_YET); 114 } 115 116 int32_t 117 eval_subtree(expr e, unsigned *lp) 118 { 119 symbol s; 120 int32_t v1, v2; 121 unsigned l2; 122 123 switch( e->e_op ){ 124 case SYM: 125 s = e->e_sym; 126 *lp = s->lineno; 127 if( (s->flags & DEFINED) != 0 ) 128 return s->value; 129 perr("Undefined symbol %s", s->name); 130 return 0; 131 case CONST: 132 *lp = 0; 133 return e->e_val; 134 case '.': 135 *lp = lineno; 136 return pc; 137 default: 138 v1 = eval_subtree(e->e_left, lp); 139 if( e->e_right == NULL ) 140 return eval_op(e->e_op, v1, 0); 141 v2 = eval_subtree(e->e_right, &l2); 142 if( l2 > *lp ) 143 *lp = l2; 144 return eval_op(e->e_op, v1, v2); 145 } 146 } 147