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Improved constant arithmetic: had several bugs

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This commit is contained in:
ceriel
1993-03-18 13:24:20 +00:00
parent eb375db4d6
commit 6fc94eb375
11 changed files with 212 additions and 66 deletions
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127
lang/cem/cpp.ansi/ch3bin.c
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@@ -8,22 +8,89 @@
#include "Lpars.h"
#include "arith.h"
ch3bin(pval, oper, val)
#define arith_sign (1 << (sizeof(arith)*8-1))
ch3bin(pval, pis_uns, oper, val, is_uns)
register arith *pval, val;
int oper;
int oper, is_uns, *pis_uns;
{
if (is_uns) *pis_uns = 1;
switch (oper) {
case '%':
if (val == 0)
error("%% by 0");
else
*pval = *pval % val;
break;
case '/':
if (val == 0)
if (val == 0) {
error("/ by 0");
else
break;
}
if (*pis_uns) {
#ifdef UNSIGNED_ARITH
*pval /= (UNSIGNED_ARITH) val;
#else
/* this is more of a problem than you might
think on C compilers which do not have
unsigned arith (== long (probably)).
*/
if (val & arith_sign) {/* val > max_arith */
*pval = ! (*pval >= 0 || *pval < val);
/* this is the unsigned test
*pval < val for val > max_arith
*/
}
else { /* val <= max_arith */
arith half, bit, hdiv, hrem, rem;
half = (*pval >> 1) & ~arith_sign;
bit = *pval & 01;
/* now *pval == 2 * half + bit
and half <= max_arith
and bit <= max_arith
*/
hdiv = half / val;
hrem = half % val;
rem = 2 * hrem + bit;
*pval = 2 * hdiv + (rem < 0 || rem >= val);
/* that is the unsigned compare
rem >= val for val <= max_arith
*/
}
#endif
}
else {
*pval = *pval % val;
}
break;
case '%':
if (val == 0) {
error("%% by 0");
break;
}
if (*pis_uns) {
#ifdef UNSIGNED_ARITH
*pval %= (UNSIGNED_ARITH) val;
#else
if (val & arith_sign) {/* val > max_arith */
*pval = (*pval >= 0 || *pval < val) ? *pval : *pval - val;
/* this is the unsigned test
*pval < val for val > max_arith
*/
}
else { /* val <= max_arith */
arith half, bit, hrem, rem;
half = (*pval >> 1) & ~arith_sign;
bit = *pval & 01;
/* now *pval == 2 * half + bit
and half <= max_arith
and bit <= max_arith
*/
hrem = half % val;
rem = 2 * hrem + bit;
*pval = (rem < 0 || rem >= val) ? rem - val : rem;
}
#endif
}
else {
*pval = *pval / val;
}
break;
case '*':
*pval = *pval * val;
@@ -38,19 +105,44 @@ ch3bin(pval, oper, val)
*pval = *pval << val;
break;
case RIGHT:
*pval = *pval >> val;
if (val == 0) break;
if (*pis_uns) {
*pval = (*pval >> 1) & ~arith_sign;
*pval = *pval >> (val - 1);
}
else *pval = *pval >> val;
break;
case '<':
*pval = (*pval < val);
break;
{ arith tmp = *pval; *pval = val; val = tmp; }
/* fall through */
case '>':
*pval = (*pval > val);
if (*pis_uns) {
#ifdef UNSIGNED_ARITH
*pval = (UNSIGNED_ARITH) *pval > (UNSIGNED_ARITH) val;
#else
*pval = (*pval & arith_sign ?
(val & arith_sign ? *pval > val : 1) :
(val & arith_sign ? 0 : *pval > val)
);
#endif
}
else *pval = (*pval > val);
break;
case LESSEQ:
*pval = (*pval <= val);
break;
{ arith tmp = *pval; *pval = val; val = tmp; }
/* fall through */
case GREATEREQ:
*pval = (*pval >= val);
if (*pis_uns) {
#ifdef UNSIGNED_ARITH
*pval = (UNSIGNED_ARITH) *pval >= (UNSIGNED_ARITH) val;
#else
*pval = (*pval & arith_sign ?
(val & arith_sign ? *pval >= val : 1) :
(val & arith_sign ? 0 : *pval >= val)
);
#endif
}
else *pval = (*pval >= val);
break;
case EQUAL:
*pval = (*pval == val);
@@ -74,6 +166,7 @@ ch3bin(pval, oper, val)
*pval = (*pval || val);
break;
case ',':
*pis_uns = is_uns;
*pval = val;
break;
}