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author | Szabolcs Nagy <nsz@port70.net> | 2013-09-03 03:27:02 +0000 |
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committer | Szabolcs Nagy <nsz@port70.net> | 2013-09-05 11:30:07 +0000 |
commit | d1a2ead878c27ac4ec600740320f8b76e1f961e9 (patch) | |
tree | 4da00576cf5df93d9170bdf76a26d9c2c96d3978 /src/math/ceilf.c | |
parent | 98be442ee8a2b8b7e0802b604e384d5a2c43282e (diff) | |
download | musl-d1a2ead878c27ac4ec600740320f8b76e1f961e9.tar.gz musl-d1a2ead878c27ac4ec600740320f8b76e1f961e9.tar.bz2 musl-d1a2ead878c27ac4ec600740320f8b76e1f961e9.tar.xz musl-d1a2ead878c27ac4ec600740320f8b76e1f961e9.zip |
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/ceilf.c')
-rw-r--r-- | src/math/ceilf.c | 65 |
1 files changed, 19 insertions, 46 deletions
diff --git a/src/math/ceilf.c b/src/math/ceilf.c index fec945b6..869835f3 100644 --- a/src/math/ceilf.c +++ b/src/math/ceilf.c @@ -1,54 +1,27 @@ -/* origin: FreeBSD /usr/src/lib/msun/src/s_ceilf.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 huge = 1.0e30; - float ceilf(float x) { - int32_t i0,j0; - uint32_t i; + union {float f; uint32_t i;} u = {x}; + int e = (int)(u.i >> 23 & 0xff) - 0x7f; + uint32_t m; - GET_FLOAT_WORD(i0, x); - j0 = ((i0>>23)&0xff) - 0x7f; - if (j0 < 23) { - if (j0 < 0) { - /* raise inexact if x != 0 */ - if (huge+x > 0.0f) { - if (i0 < 0) - i0 = 0x80000000; - else if(i0 != 0) - i0 = 0x3f800000; - } - } else { - i = 0x007fffff>>j0; - if ((i0&i) == 0) - return x; /* x is integral */ - /* raise inexact flag */ - if (huge+x > 0.0f) { - if (i0 > 0) - i0 += 0x00800000>>j0; - i0 &= ~i; - } - } + if (e >= 23) + return x; + if (e >= 0) { + m = 0x007fffff >> e; + if ((u.i & m) == 0) + return x; + FORCE_EVAL(x + 0x1p120f); + if (u.i >> 31 == 0) + u.i += m; + u.i &= ~m; } else { - if (j0 == 0x80) /* inf or NaN */ - return x+x; - return x; /* x is integral */ + FORCE_EVAL(x + 0x1p120f); + if (u.i >> 31) + u.f = -0.0; + else if (u.i << 1) + u.f = 1.0; } - SET_FLOAT_WORD(x, i0); - return x; + return u.f; } |