174 lines
3.5 KiB
C
174 lines
3.5 KiB
C
/*
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* (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
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* See the copyright notice in the ACK home directory, in the file "Copyright".
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*/
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/* $Id$ */
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/* EVALUATION OF BINARY OPERATORS */
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#include "Lpars.h"
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#include "arith.h"
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#define arith_sign (1 << (sizeof(arith)*8-1))
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ch3bin(pval, pis_uns, oper, val, is_uns)
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register arith *pval, val;
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int oper, is_uns, *pis_uns;
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{
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if (is_uns) *pis_uns = 1;
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switch (oper) {
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case '/':
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if (val == 0) {
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error("/ by 0");
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break;
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}
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if (*pis_uns) {
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#ifdef UNSIGNED_ARITH
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*pval /= (UNSIGNED_ARITH) val;
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#else
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/* this is more of a problem than you might
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think on C compilers which do not have
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unsigned arith (== long (probably)).
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*/
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if (val & arith_sign) {/* val > max_arith */
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*pval = ! (*pval >= 0 || *pval < val);
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/* this is the unsigned test
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*pval < val for val > max_arith
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*/
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}
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else { /* val <= max_arith */
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arith half, bit, hdiv, hrem, rem;
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half = (*pval >> 1) & ~arith_sign;
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bit = *pval & 01;
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/* now *pval == 2 * half + bit
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and half <= max_arith
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and bit <= max_arith
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*/
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hdiv = half / val;
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hrem = half % val;
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rem = 2 * hrem + bit;
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*pval = 2 * hdiv + (rem < 0 || rem >= val);
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/* that is the unsigned compare
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rem >= val for val <= max_arith
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*/
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}
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#endif
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}
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else {
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*pval = *pval / val;
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}
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break;
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case '%':
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if (val == 0) {
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error("%% by 0");
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break;
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}
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if (*pis_uns) {
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#ifdef UNSIGNED_ARITH
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*pval %= (UNSIGNED_ARITH) val;
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#else
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if (val & arith_sign) {/* val > max_arith */
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*pval = (*pval >= 0 || *pval < val) ? *pval : *pval - val;
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/* this is the unsigned test
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*pval < val for val > max_arith
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*/
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}
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else { /* val <= max_arith */
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arith half, bit, hrem, rem;
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half = (*pval >> 1) & ~arith_sign;
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bit = *pval & 01;
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/* now *pval == 2 * half + bit
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and half <= max_arith
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and bit <= max_arith
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*/
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hrem = half % val;
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rem = 2 * hrem + bit;
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*pval = (rem < 0 || rem >= val) ? rem - val : rem;
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}
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#endif
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}
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else {
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*pval = *pval % val;
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}
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break;
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case '*':
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*pval = *pval * val;
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break;
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case '+':
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*pval = *pval + val;
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break;
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case '-':
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*pval = *pval - val;
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break;
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case LEFT:
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*pval = *pval << val;
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break;
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case RIGHT:
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if (val == 0) break;
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if (*pis_uns) {
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*pval = (*pval >> 1) & ~arith_sign;
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*pval = *pval >> (val - 1);
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}
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else *pval = *pval >> val;
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break;
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case '<':
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{ arith tmp = *pval; *pval = val; val = tmp; }
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/* fall through */
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case '>':
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if (*pis_uns) {
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#ifdef UNSIGNED_ARITH
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*pval = (UNSIGNED_ARITH) *pval > (UNSIGNED_ARITH) val;
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#else
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*pval = (*pval & arith_sign ?
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(val & arith_sign ? *pval > val : 1) :
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(val & arith_sign ? 0 : *pval > val)
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);
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#endif
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}
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else *pval = (*pval > val);
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break;
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case LESSEQ:
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{ arith tmp = *pval; *pval = val; val = tmp; }
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/* fall through */
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case GREATEREQ:
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if (*pis_uns) {
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#ifdef UNSIGNED_ARITH
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*pval = (UNSIGNED_ARITH) *pval >= (UNSIGNED_ARITH) val;
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#else
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*pval = (*pval & arith_sign ?
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(val & arith_sign ? *pval >= val : 1) :
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(val & arith_sign ? 0 : *pval >= val)
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);
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#endif
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}
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else *pval = (*pval >= val);
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break;
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case EQUAL:
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*pval = (*pval == val);
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break;
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case NOTEQUAL:
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*pval = (*pval != val);
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break;
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case '&':
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*pval = *pval & val;
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break;
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case '^':
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*pval = *pval ^ val;
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break;
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case '|':
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*pval = *pval | val;
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break;
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case AND:
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*pval = (*pval && val);
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break;
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case OR:
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*pval = (*pval || val);
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break;
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case ',':
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*pis_uns = is_uns;
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*pval = val;
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break;
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}
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}
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