From d1a2ead878c27ac4ec600740320f8b76e1f961e9 Mon Sep 17 00:00:00 2001 From: Szabolcs Nagy Date: Tue, 3 Sep 2013 03:27:02 +0000 Subject: 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) --- src/math/rintf.c | 58 +++++++++++++++----------------------------------------- 1 file changed, 15 insertions(+), 43 deletions(-) (limited to 'src/math/rintf.c') 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 +#include 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; } -- cgit v1.2.1