Mercurial > sdl-ios-xcode
diff src/libm/s_floor.c @ 2758:045d9976f285
Yet more math...
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Mon, 15 Sep 2008 06:48:41 +0000 |
parents | |
children | 02aa80d7905f |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/libm/s_floor.c Mon Sep 15 06:48:41 2008 +0000 @@ -0,0 +1,96 @@ +/* @(#)s_floor.c 5.1 93/09/24 */ +/* + * ==================================================== + * 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. + * ==================================================== + */ + +#if defined(LIBM_SCCS) && !defined(lint) +static char rcsid[] = + "$NetBSD: s_floor.c,v 1.8 1995/05/10 20:47:20 jtc Exp $"; +#endif + +/* + * floor(x) + * Return x rounded toward -inf to integral value + * Method: + * Bit twiddling. + * Exception: + * Inexact flag raised if x not equal to floor(x). + */ + +#include "math.h" +#include "math_private.h" + +#ifdef __STDC__ +static const double huge = 1.0e300; +#else +static double huge = 1.0e300; +#endif + +libm_hidden_proto(floor) +#ifdef __STDC__ + double floor(double x) +#else + double floor(x) + double x; +#endif +{ + int32_t i0, i1, j0; + u_int32_t i, j; + EXTRACT_WORDS(i0, i1, x); + j0 = ((i0 >> 20) & 0x7ff) - 0x3ff; + if (j0 < 20) { + if (j0 < 0) { /* raise inexact if x != 0 */ + if (huge + x > 0.0) { /* return 0*sign(x) if |x|<1 */ + if (i0 >= 0) { + i0 = i1 = 0; + } else if (((i0 & 0x7fffffff) | i1) != 0) { + i0 = 0xbff00000; + i1 = 0; + } + } + } else { + i = (0x000fffff) >> j0; + if (((i0 & i) | i1) == 0) + return x; /* x is integral */ + if (huge + x > 0.0) { /* raise inexact flag */ + if (i0 < 0) + i0 += (0x00100000) >> j0; + i0 &= (~i); + i1 = 0; + } + } + } else if (j0 > 51) { + if (j0 == 0x400) + return x + x; /* inf or NaN */ + else + return x; /* x is integral */ + } else { + i = ((u_int32_t) (0xffffffff)) >> (j0 - 20); + if ((i1 & i) == 0) + return x; /* x is integral */ + if (huge + x > 0.0) { /* raise inexact flag */ + if (i0 < 0) { + if (j0 == 20) + i0 += 1; + else { + j = i1 + (1 << (52 - j0)); + if (j < i1) + i0 += 1; /* got a carry */ + i1 = j; + } + } + i1 &= (~i); + } + } + INSERT_WORDS(x, i0, i1); + return x; +} + +libm_hidden_def(floor)