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50 lines
1015 B
C
50 lines
1015 B
C
#if defined(__GNUC__) && (__GNUC__ >= 5)
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#include "uint64.h"
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int imult64( int64 a, int64 b, int64* c) { return !__builtin_mul_overflow(a,b,c); }
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#else
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#include "safemult.h"
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#if defined(__GNUC__) && (defined(__x86_64__) || defined(__ia64__) || defined(__powerpc64__) || defined(__alpha__) || defined(__mips64__) || defined(__sparc64__))
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int imult64(int64 a,int64 b,int64* c) {
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__int128_t x=((__int128_t)a)*b;
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if ((*c=(int64)x) != x) return 0;
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return 1;
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}
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#else
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int imult64(int64 a,int64 b,int64* c) {
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int neg=(a<0);
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uint64 d;
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if (neg) a=-a;
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if (b<0) { neg^=1; b=-b; }
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if (!umult64(a,b,&d)) return 0;
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if (d > 0x7fffffffffffffffULL + neg) return 0;
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*c=(neg?-d:d);
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return 1;
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}
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#endif
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#endif
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#ifdef UNITTEST
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#include <assert.h>
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int main() {
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int64 c;
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assert(imult64(0x4000000000000000ll,2,&c)==0);
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assert(imult64(-0x4000000000000000ll,2,&c)==1 && c==(int64)-0x8000000000000000ll);
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assert(imult64(0x3fffffffffffffffll,2,&c)==1 && c==0x7ffffffffffffffell);
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return 0;
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}
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#endif
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