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authorSzabolcs Nagy <nsz@port70.net>2013-09-03 03:27:02 +0000
committerSzabolcs Nagy <nsz@port70.net>2013-09-05 11:30:07 +0000
commitd1a2ead878c27ac4ec600740320f8b76e1f961e9 (patch)
tree4da00576cf5df93d9170bdf76a26d9c2c96d3978 /src/math/rintf.c
parent98be442ee8a2b8b7e0802b604e384d5a2c43282e (diff)
downloadmusl-d1a2ead878c27ac4ec600740320f8b76e1f961e9.tar.gz
math: rewrite rounding functions (ceil, floor, trunc, round, rint)
* faster, smaller, cleaner implementation than the bit hacks of fdlibm * use arithmetics like y=(double)(x+0x1p52)-0x1p52, which is an integer neighbor of x in all rounding modes (0<=x<0x1p52) and only use bithacks when that's faster and smaller (for float it usually is) * the code assumes standard excess precision handling for casts * long double code supports both ld80 and ld128 * nearbyint is not changed (it is a wrapper around rint)
Diffstat (limited to 'src/math/rintf.c')
-rw-r--r--src/math/rintf.c58
1 files changed, 15 insertions, 43 deletions
diff --git a/src/math/rintf.c b/src/math/rintf.c
index e8d44969..9cfc2a26 100644
--- a/src/math/rintf.c
+++ b/src/math/rintf.c
@@ -1,48 +1,20 @@
-/* origin: FreeBSD /usr/src/lib/msun/src/s_rintf.c */
-/*
- * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
- */
-/*
- * ====================================================
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- * Developed at SunPro, a Sun Microsystems, Inc. business.
- * Permission to use, copy, modify, and distribute this
- * software is freely granted, provided that this notice
- * is preserved.
- * ====================================================
- */
-
-#include "libm.h"
-
-static const float
-TWO23[2] = {
- 8.3886080000e+06, /* 0x4b000000 */
- -8.3886080000e+06, /* 0xcb000000 */
-};
+#include <math.h>
+#include <stdint.h>
float rintf(float x)
{
- int32_t i0,j0,sx;
- float w,t;
+ union {float f; uint32_t i;} u = {x};
+ int e = u.i>>23 & 0xff;
+ int s = u.i>>31;
+ float_t y;
- GET_FLOAT_WORD(i0, x);
- sx = (i0>>31) & 1;
- j0 = ((i0>>23)&0xff) - 0x7f;
- if (j0 < 23) {
- if (j0 < 0) {
- if ((i0&0x7fffffff) == 0)
- return x;
- STRICT_ASSIGN(float, w, TWO23[sx] + x);
- t = w - TWO23[sx];
- GET_FLOAT_WORD(i0, t);
- SET_FLOAT_WORD(t, (i0&0x7fffffff)|(sx<<31));
- return t;
- }
- STRICT_ASSIGN(float, w, TWO23[sx] + x);
- return w - TWO23[sx];
- }
- if (j0 == 0x80)
- return x+x; /* inf or NaN */
- return x; /* x is integral */
+ if (e >= 0x7f+23)
+ return x;
+ if (s)
+ y = (float)(x - 0x1p23f) + 0x1p23f;
+ else
+ y = (float)(x + 0x1p23f) - 0x1p23f;
+ if (y == 0)
+ return s ? -0.0f : 0.0f;
+ return y;
}