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#if defined(__x86_64__) && defined(__OPTIMIZE__)
/* WARNING: this only works if compiled with -fomit-frame-pointer */
void imult64() {
asm volatile(
"xchgq %rdx,%rsi\n"
"movq %rdi,%rax\n"
"imulq %rdx\n"
"jc 1f\n" /* overflow */
"movq %rax,(%rsi)\n"
"xorq %rax,%rax\n"
"inc %rax\n"
"ret\n"
"1:\n"
"xorq %rax,%rax\n"
/* the closing ret is renerated by gcc */
);
}
#else
#include "safemult.h"
#if defined(__GNUC__) && (defined(__x86_64__) || defined(__ia64__) || defined(__powerpc64__) || defined(__alpha__) || defined(__mips64__) || defined(__sparc64__))
int imult64(int64 a,int64 b,int64* c) {
__int128_t x=((__int128_t)a)*b;
if ((*c=(int64)x) != x) return 0;
return 1;
}
#else
int imult64(int64 a,int64 b,int64* c) {
int neg=(a<0);
uint64 d;
if (neg) a=-a;
if (b<0) { neg^=1; b=-b; }
if (!umult64(a,b,&d)) return 0;
if (d > 0x7fffffffffffffffULL + neg) return 0;
*c=(neg?-d:d);
return 1;
}
#endif
#endif
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