diff options
Diffstat (limited to 'sysdeps/ieee754/dbl-64/s_scalbn.c')
| -rw-r--r-- | sysdeps/ieee754/dbl-64/s_scalbn.c | 63 |
1 files changed, 30 insertions, 33 deletions
diff --git a/sysdeps/ieee754/dbl-64/s_scalbn.c b/sysdeps/ieee754/dbl-64/s_scalbn.c index cf4d6846ee..4491227f3e 100644 --- a/sysdeps/ieee754/dbl-64/s_scalbn.c +++ b/sysdeps/ieee754/dbl-64/s_scalbn.c @@ -20,43 +20,40 @@ #include <math_private.h> static const double - two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */ - twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */ - huge = 1.0e+300, - tiny = 1.0e-300; +two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */ +twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */ +huge = 1.0e+300, +tiny = 1.0e-300; double __scalbn (double x, int n) { - int32_t k, hx, lx; - EXTRACT_WORDS (hx, lx, x); - k = (hx & 0x7ff00000) >> 20; /* extract exponent */ - if (__glibc_unlikely (k == 0)) /* 0 or subnormal x */ - { - if ((lx | (hx & 0x7fffffff)) == 0) - return x; /* +-0 */ - x *= two54; - GET_HIGH_WORD (hx, x); - k = ((hx & 0x7ff00000) >> 20) - 54; - } - if (__glibc_unlikely (k == 0x7ff)) - return x + x; /* NaN or Inf */ - if (__glibc_unlikely (n < -50000)) - return tiny * copysign (tiny, x); /*underflow*/ - if (__glibc_unlikely (n > 50000 || k + n > 0x7fe)) - return huge * copysign (huge, x); /* overflow */ - /* Now k and n are bounded we know that k = k+n does not - overflow. */ - k = k + n; - if (__glibc_likely (k > 0)) /* normal result */ - { - SET_HIGH_WORD (x, (hx & 0x800fffff) | (k << 20)); return x; - } - if (k <= -54) - return tiny * copysign (tiny, x); /*underflow*/ - k += 54; /* subnormal result */ - SET_HIGH_WORD (x, (hx & 0x800fffff) | (k << 20)); - return x * twom54; + int64_t ix; + int64_t k; + EXTRACT_WORDS64(ix,x); + k = (ix >> 52) & 0x7ff; /* extract exponent */ + if (__builtin_expect(k==0, 0)) { /* 0 or subnormal x */ + if ((ix & UINT64_C(0xfffffffffffff))==0) return x; /* +-0 */ + x *= two54; + EXTRACT_WORDS64(ix,x); + k = ((ix >> 52) & 0x7ff) - 54; + } + if (__builtin_expect(k==0x7ff, 0)) return x+x; /* NaN or Inf */ + if (__builtin_expect(n< -50000, 0)) + return tiny*copysign(tiny,x); /*underflow*/ + if (__builtin_expect(n> 50000 || k+n > 0x7fe, 0)) + return huge*copysign(huge,x); /* overflow */ + /* Now k and n are bounded we know that k = k+n does not + overflow. */ + k = k+n; + if (__builtin_expect(k > 0, 1)) /* normal result */ + {INSERT_WORDS64(x,(ix&UINT64_C(0x800fffffffffffff))|(k<<52)); + return x;} + if (k <= -54) + return tiny*copysign(tiny,x); /*underflow*/ + k += 54; /* subnormal result */ + INSERT_WORDS64(x,(ix&INT64_C(0x800fffffffffffff))|(k<<52)); + return x*twom54; } #ifdef NO_LONG_DOUBLE strong_alias (__scalbn, __scalbnl) |