| author | Holmes Futrell <hfutrell@umail.ucsb.edu> |
| Thu, 01 Jan 2009 23:49:28 +0000 | |
| changeset 2950 | 04c9f1e4c496 |
| parent 2765 | f55c87ae336b |
| child 3162 | dc1eb82ffdaa |
| permissions | -rw-r--r-- |
| 2758 | 1 |
/* @(#)s_floor.c 5.1 93/09/24 */ |
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/* |
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* ==================================================== |
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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* |
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* Developed at SunPro, a Sun Microsystems, Inc. business. |
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* Permission to use, copy, modify, and distribute this |
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* software is freely granted, provided that this notice |
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* is preserved. |
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* ==================================================== |
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*/ |
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#if defined(LIBM_SCCS) && !defined(lint) |
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static char rcsid[] = |
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"$NetBSD: s_floor.c,v 1.8 1995/05/10 20:47:20 jtc Exp $"; |
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#endif |
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/* |
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* floor(x) |
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* Return x rounded toward -inf to integral value |
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* Method: |
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* Bit twiddling. |
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* Exception: |
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* Inexact flag raised if x not equal to floor(x). |
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*/ |
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#include "math.h" |
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#include "math_private.h" |
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#ifdef __STDC__ |
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static const double huge = 1.0e300; |
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#else |
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static double huge = 1.0e300; |
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#endif |
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libm_hidden_proto(floor) |
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#ifdef __STDC__ |
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double floor(double x) |
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#else |
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double floor(x) |
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double x; |
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#endif |
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{
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int32_t i0, i1, j0; |
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u_int32_t i, j; |
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EXTRACT_WORDS(i0, i1, x); |
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j0 = ((i0 >> 20) & 0x7ff) - 0x3ff; |
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if (j0 < 20) {
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if (j0 < 0) { /* raise inexact if x != 0 */
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if (huge + x > 0.0) { /* return 0*sign(x) if |x|<1 */
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if (i0 >= 0) {
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i0 = i1 = 0; |
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} else if (((i0 & 0x7fffffff) | i1) != 0) {
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i0 = 0xbff00000; |
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i1 = 0; |
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} |
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} |
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} else {
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i = (0x000fffff) >> j0; |
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if (((i0 & i) | i1) == 0) |
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return x; /* x is integral */ |
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if (huge + x > 0.0) { /* raise inexact flag */
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if (i0 < 0) |
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i0 += (0x00100000) >> j0; |
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i0 &= (~i); |
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i1 = 0; |
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} |
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} |
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} else if (j0 > 51) {
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if (j0 == 0x400) |
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return x + x; /* inf or NaN */ |
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else |
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return x; /* x is integral */ |
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} else {
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i = ((u_int32_t) (0xffffffff)) >> (j0 - 20); |
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if ((i1 & i) == 0) |
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return x; /* x is integral */ |
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if (huge + x > 0.0) { /* raise inexact flag */
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if (i0 < 0) {
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if (j0 == 20) |
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i0 += 1; |
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else {
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j = i1 + (1 << (52 - j0)); |
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2765
f55c87ae336b
Final merge of Google Summer of Code 2008 work...
Sam Lantinga <slouken@libsdl.org>
parents:
2760
diff
changeset
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if (j < (u_int32_t) i1) |
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i0 += 1; /* got a carry */ |
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i1 = j; |
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} |
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} |
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i1 &= (~i); |
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} |
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} |
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INSERT_WORDS(x, i0, i1); |
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return x; |
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} |
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libm_hidden_def(floor) |