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authorSzabolcs Nagy <nsz@port70.net>2013-09-03 04:09:12 +0000
committerSzabolcs Nagy <nsz@port70.net>2013-09-05 11:30:07 +0000
commitee2ee92d62c43f6658d37ddea4c316d2089d0fe9 (patch)
tree1a3e5a63fd40fa763f87d5dd9efd021117ea1d11 /src/math/remainder.c
parentd1a2ead878c27ac4ec600740320f8b76e1f961e9 (diff)
downloadmusl-ee2ee92d62c43f6658d37ddea4c316d2089d0fe9.tar.gz
math: rewrite remainder functions (remainder, remquo, fmod, modf)
* results are exact * modfl follows truncl (raises inexact flag spuriously now) * modf and modff only had cosmetic cleanup * remainder is just a wrapper around remquo now * using iterative shift+subtract for remquo and fmod * ld80 and ld128 are supported as well
Diffstat (limited to 'src/math/remainder.c')
-rw-r--r--src/math/remainder.c67
1 files changed, 4 insertions, 63 deletions
diff --git a/src/math/remainder.c b/src/math/remainder.c
index 2dede3a8..ed5c477e 100644
--- a/src/math/remainder.c
+++ b/src/math/remainder.c
@@ -1,66 +1,7 @@
-/* origin: FreeBSD /usr/src/lib/msun/src/e_remainder.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.
- * ====================================================
- */
-/* remainder(x,p)
- * Return :
- * returns x REM p = x - [x/p]*p as if in infinite
- * precise arithmetic, where [x/p] is the (infinite bit)
- * integer nearest x/p (in half way case choose the even one).
- * Method :
- * Based on fmod() return x-[x/p]chopped*p exactlp.
- */
+#include <math.h>
-#include "libm.h"
-
-double remainder(double x, double p)
+double remainder(double x, double y)
{
- int32_t hx,hp;
- uint32_t sx,lx,lp;
- double p_half;
-
- EXTRACT_WORDS(hx, lx, x);
- EXTRACT_WORDS(hp, lp, p);
- sx = hx & 0x80000000;
- hp &= 0x7fffffff;
- hx &= 0x7fffffff;
-
- /* purge off exception values */
- if ((hp|lp) == 0 || /* p = 0 */
- hx >= 0x7ff00000 || /* x not finite */
- (hp >= 0x7ff00000 && (hp-0x7ff00000 | lp) != 0)) /* p is NaN */
- return (x*p)/(x*p);
-
- if (hp <= 0x7fdfffff)
- x = fmod(x, p+p); /* now x < 2p */
- if (((hx-hp)|(lx-lp)) == 0)
- return 0.0*x;
- x = fabs(x);
- p = fabs(p);
- if (hp < 0x00200000) {
- if (x + x > p) {
- x -= p;
- if (x + x >= p)
- x -= p;
- }
- } else {
- p_half = 0.5*p;
- if (x > p_half) {
- x -= p;
- if (x >= p_half)
- x -= p;
- }
- }
- GET_HIGH_WORD(hx, x);
- if ((hx&0x7fffffff) == 0)
- hx = 0;
- SET_HIGH_WORD(x, hx^sx);
- return x;
+ int q;
+ return remquo(x, y, &q);
}