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Signed multiplication overflow check

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This commit is contained in:
Justin Ethier 2017-02-16 03:01:26 -05:00
parent ad51bc7e80
commit 9899189c60
1 changed files with 4 additions and 2 deletions
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6
runtime.c
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@ -2489,6 +2489,8 @@ object __halt(object obj)
return NULL;
}
// Signed arithmetic overflow checks, based on code from CHICKEN:
static int Cyc_checked_add(int x, int y, int *result)
{
*result = x + y;
@ -2501,11 +2503,11 @@ static int Cyc_checked_sub(int x, int y, int *result)
return ((((*result ^ x) & ~(*result ^ y)) >> 30) != 0);
}
// TODO: overflow checking
// Code from http://stackoverflow.com/q/1815367/101258
static int Cyc_checked_mul(int x, int y, int *result)
{
*result = x * y;
return 0;
return (*result != 0 && (*result)/x != y);
}
#define declare_num_op(FUNC, FUNC_OP, FUNC_APPLY, OP, INT_OP, BN_OP, NO_ARG, ONE_ARG, DIV) \