diff options
Diffstat (limited to 'lib/msun/src/e_log10f.c')
| -rw-r--r-- | lib/msun/src/e_log10f.c | 23 |
1 files changed, 16 insertions, 7 deletions
diff --git a/lib/msun/src/e_log10f.c b/lib/msun/src/e_log10f.c index 960b608..4665898 100644 --- a/lib/msun/src/e_log10f.c +++ b/lib/msun/src/e_log10f.c @@ -32,7 +32,7 @@ static const float zero = 0.0; float __ieee754_log10f(float x) { - float f,hi,lo,y,z; + float f,hfsq,hi,lo,r,y,y2; int32_t i,k,hx; GET_FLOAT_WORD(hx,x); @@ -46,17 +46,26 @@ __ieee754_log10f(float x) GET_FLOAT_WORD(hx,x); } if (hx >= 0x7f800000) return x+x; + if (hx == 0x3f800000) + return zero; /* log(1) = +0 */ k += (hx>>23)-127; hx &= 0x007fffff; i = (hx+(0x4afb0d))&0x800000; SET_FLOAT_WORD(x,hx|(i^0x3f800000)); /* normalize x or x/2 */ k += (i>>23); y = (float)k; - f = __kernel_logf(x); - x = x - (float)1.0; - GET_FLOAT_WORD(hx,x); + f = x - (float)1.0; + hfsq = (float)0.5*f*f; + r = k_log1pf(f); + + /* See e_log2f.c and e_log2.c for details. */ + if (sizeof(float_t) > sizeof(float)) + return (r - hfsq + f) * ((float_t)ivln10lo + ivln10hi) + + y * ((float_t)log10_2lo + log10_2hi); + hi = f - hfsq; + GET_FLOAT_WORD(hx,hi); SET_FLOAT_WORD(hi,hx&0xfffff000); - lo = x - hi; - z = y*log10_2lo + (x+f)*ivln10lo + (lo+f)*ivln10hi + hi*ivln10hi; - return z+y*log10_2hi; + lo = (f - hi) - hfsq + r; + return y*log10_2lo + (lo+hi)*ivln10lo + lo*ivln10hi + hi*ivln10hi + + y*log10_2hi; } |
