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#if defined(__GNUC__) && (__GNUC__ >= 5)
#include "uint32.h"
int umult32(uint32 a,uint32 b,uint32* c) { return !__builtin_mul_overflow(a,b,c); }
#include "safemult.h"
int umult32(uint32 a,uint32 b,uint32* c) {
unsigned long long x=(unsigned long long)a*b;
if (x>0xffffffff) return 0;
return 1;
#include <assert.h>
int main() {
uint32 a;
assert(umult32(16,0x45000000,&a)==0); // make sure we don't fall for "if a*b<a && a*b<b"
assert(umult32(5,10,&a)==1 && a==50);
assert(umult32(6,0x10000000,&a)==1 && a==0x60000000);
return 0;