summaryrefslogtreecommitdiff
path: root/lib/mlibc/options/ansi/musl-generic-math/log10.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/mlibc/options/ansi/musl-generic-math/log10.c')
-rw-r--r--lib/mlibc/options/ansi/musl-generic-math/log10.c101
1 files changed, 0 insertions, 101 deletions
diff --git a/lib/mlibc/options/ansi/musl-generic-math/log10.c b/lib/mlibc/options/ansi/musl-generic-math/log10.c
deleted file mode 100644
index 8102687..0000000
--- a/lib/mlibc/options/ansi/musl-generic-math/log10.c
+++ /dev/null
@@ -1,101 +0,0 @@
-/* origin: FreeBSD /usr/src/lib/msun/src/e_log10.c */
-/*
- * ====================================================
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- * Developed at SunSoft, a Sun Microsystems, Inc. business.
- * Permission to use, copy, modify, and distribute this
- * software is freely granted, provided that this notice
- * is preserved.
- * ====================================================
- */
-/*
- * Return the base 10 logarithm of x. See log.c for most comments.
- *
- * Reduce x to 2^k (1+f) and calculate r = log(1+f) - f + f*f/2
- * as in log.c, then combine and scale in extra precision:
- * log10(x) = (f - f*f/2 + r)/log(10) + k*log10(2)
- */
-
-#include <math.h>
-#include <stdint.h>
-
-static const double
-ivln10hi = 4.34294481878168880939e-01, /* 0x3fdbcb7b, 0x15200000 */
-ivln10lo = 2.50829467116452752298e-11, /* 0x3dbb9438, 0xca9aadd5 */
-log10_2hi = 3.01029995663611771306e-01, /* 0x3FD34413, 0x509F6000 */
-log10_2lo = 3.69423907715893078616e-13, /* 0x3D59FEF3, 0x11F12B36 */
-Lg1 = 6.666666666666735130e-01, /* 3FE55555 55555593 */
-Lg2 = 3.999999999940941908e-01, /* 3FD99999 9997FA04 */
-Lg3 = 2.857142874366239149e-01, /* 3FD24924 94229359 */
-Lg4 = 2.222219843214978396e-01, /* 3FCC71C5 1D8E78AF */
-Lg5 = 1.818357216161805012e-01, /* 3FC74664 96CB03DE */
-Lg6 = 1.531383769920937332e-01, /* 3FC39A09 D078C69F */
-Lg7 = 1.479819860511658591e-01; /* 3FC2F112 DF3E5244 */
-
-double log10(double x)
-{
- union {double f; uint64_t i;} u = {x};
- double_t hfsq,f,s,z,R,w,t1,t2,dk,y,hi,lo,val_hi,val_lo;
- uint32_t hx;
- int k;
-
- hx = u.i>>32;
- k = 0;
- if (hx < 0x00100000 || hx>>31) {
- if (u.i<<1 == 0)
- return -1/(x*x); /* log(+-0)=-inf */
- if (hx>>31)
- return (x-x)/0.0; /* log(-#) = NaN */
- /* subnormal number, scale x up */
- k -= 54;
- x *= 0x1p54;
- u.f = x;
- hx = u.i>>32;
- } else if (hx >= 0x7ff00000) {
- return x;
- } else if (hx == 0x3ff00000 && u.i<<32 == 0)
- return 0;
-
- /* reduce x into [sqrt(2)/2, sqrt(2)] */
- hx += 0x3ff00000 - 0x3fe6a09e;
- k += (int)(hx>>20) - 0x3ff;
- hx = (hx&0x000fffff) + 0x3fe6a09e;
- u.i = (uint64_t)hx<<32 | (u.i&0xffffffff);
- x = u.f;
-
- f = x - 1.0;
- hfsq = 0.5*f*f;
- s = f/(2.0+f);
- z = s*s;
- w = z*z;
- t1 = w*(Lg2+w*(Lg4+w*Lg6));
- t2 = z*(Lg1+w*(Lg3+w*(Lg5+w*Lg7)));
- R = t2 + t1;
-
- /* See log2.c for details. */
- /* hi+lo = f - hfsq + s*(hfsq+R) ~ log(1+f) */
- hi = f - hfsq;
- u.f = hi;
- u.i &= (uint64_t)-1<<32;
- hi = u.f;
- lo = f - hi - hfsq + s*(hfsq+R);
-
- /* val_hi+val_lo ~ log10(1+f) + k*log10(2) */
- val_hi = hi*ivln10hi;
- dk = k;
- y = dk*log10_2hi;
- val_lo = dk*log10_2lo + (lo+hi)*ivln10lo + lo*ivln10hi;
-
- /*
- * Extra precision in for adding y is not strictly needed
- * since there is no very large cancellation near x = sqrt(2) or
- * x = 1/sqrt(2), but we do it anyway since it costs little on CPUs
- * with some parallelism and it reduces the error for many args.
- */
- w = y + val_hi;
- val_lo += (y - w) + val_hi;
- val_hi = w;
-
- return val_lo + val_hi;
-}