56 lines
1019 B
C
56 lines
1019 B
C
#include "libc/limits.h"
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#include "libc/math/libm.h"
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#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
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int ilogbl(long double x)
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{
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return ilogb(x);
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}
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#elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
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int ilogbl(long double x)
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{
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#pragma STDC FENV_ACCESS ON
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union ldshape u = {x};
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uint64_t m = u.i.m;
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int e = u.i.se & 0x7fff;
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if (!e) {
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if (m == 0) {
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FORCE_EVAL(0/0.0f);
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return FP_ILOGB0;
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}
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/* subnormal x */
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for (e = -0x3fff+1; m>>63 == 0; e--, m<<=1);
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return e;
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}
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if (e == 0x7fff) {
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FORCE_EVAL(0/0.0f);
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return m<<1 ? FP_ILOGBNAN : INT_MAX;
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}
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return e - 0x3fff;
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}
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#elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384
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int ilogbl(long double x)
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{
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#pragma STDC FENV_ACCESS ON
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union ldshape u = {x};
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int e = u.i.se & 0x7fff;
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if (!e) {
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if (x == 0) {
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FORCE_EVAL(0/0.0f);
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return FP_ILOGB0;
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}
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/* subnormal x */
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x *= 0x1p120;
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return ilogbl(x) - 120;
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}
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if (e == 0x7fff) {
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FORCE_EVAL(0/0.0f);
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u.i.se = 0;
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return u.f ? FP_ILOGBNAN : INT_MAX;
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}
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return e - 0x3fff;
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}
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#endif
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