c4359e0130
old code was correct only if the result was stored (without the excess precision) or musl was compiled with -ffloat-store. now we use STRICT_ASSIGN to work around the issue. (see note 160 in c11 section 6.8.6.4)
37 lines
603 B
C
37 lines
603 B
C
#include "libm.h"
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double modf(double x, double *iptr)
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{
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union {double x; uint64_t n;} u = {x};
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uint64_t mask;
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int e;
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e = (int)(u.n>>52 & 0x7ff) - 0x3ff;
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/* no fractional part */
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if (e >= 52) {
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*iptr = x;
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if (e == 0x400 && u.n<<12 != 0) /* nan */
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return x;
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u.n &= (uint64_t)1<<63;
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return u.x;
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}
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/* no integral part*/
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if (e < 0) {
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u.n &= (uint64_t)1<<63;
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*iptr = u.x;
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return x;
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}
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mask = (uint64_t)-1>>12 >> e;
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if ((u.n & mask) == 0) {
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*iptr = x;
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u.n &= (uint64_t)1<<63;
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return u.x;
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}
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u.n &= ~mask;
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*iptr = u.x;
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STRICT_ASSIGN(double, x, x - *iptr);
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return x;
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}
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