59b3c10563
This prevents an overflow reported by @hexcoder- in https://github.com/davidgiven/ack/issues/56 lang/cem/cpp.ansi/LLlex.c used a plain 1 << ... and caused an overflow on machines where sizeof(int) < sizeof(long). Using 1L << ... would work for now but might fail later if arith became long long. C doesn't specify whether negative integers use 2's complement or some other format. Therefore, (arith) 1 << ... has an undefined value. It should still work because the value is some integer where the sign bit is set and all other bits are clear. (unsigned arith) 1 << ... would also get the sign bit, but casting it from unsigned back to signed would make the same undefined value. (arith) -1 << ... would assume 2's complement.
105 lines
1.8 KiB
C
105 lines
1.8 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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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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*pval /= (unsigned arith) val;
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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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*pval %= (unsigned arith) val;
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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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*pval = (unsigned arith) *pval > (unsigned arith) val;
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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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*pval = (unsigned arith) *pval >= (unsigned arith) val;
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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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