Fcalva/cyclone
1
0
Fork 0
mirror of https://github.com/justinethier/cyclone.git synced 2025-05-24 20:45:06 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

Signed multiplication overflow check

Browse source
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
Show stats Download patch file Download diff file Expand all files Collapse all files

6
runtime.c
View file

@ -2489,6 +2489,8 @@ object __halt(object obj)
return NULL; return NULL;
} }
// Signed arithmetic overflow checks, based on code from CHICKEN:
static int Cyc_checked_add(int x, int y, int *result) static int Cyc_checked_add(int x, int y, int *result)
{ {
*result = x + y; *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); 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) static int Cyc_checked_mul(int x, int y, int *result)
{ {
*result = x * y; *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) \ #define declare_num_op(FUNC, FUNC_OP, FUNC_APPLY, OP, INT_OP, BN_OP, NO_ARG, ONE_ARG, DIV) \