Mercurial > sdl-ios-xcode
annotate src/libm/s_floor.c @ 2960:91708bc14aab
It's probably not worth pushing palettized textures. The memory optimization
isn't worth the effort on modern hardware with the sorts of games that would
be using the SDL 1.3 texture API.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Fri, 02 Jan 2009 09:27:36 +0000 |
| parents | f55c87ae336b |
| children | dc1eb82ffdaa |
| rev | line source |
|---|---|
| 2758 | 1 /* @(#)s_floor.c 5.1 93/09/24 */ |
| 2 /* | |
| 3 * ==================================================== | |
| 4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. | |
| 5 * | |
| 6 * Developed at SunPro, a Sun Microsystems, Inc. business. | |
| 7 * Permission to use, copy, modify, and distribute this | |
| 8 * software is freely granted, provided that this notice | |
| 9 * is preserved. | |
| 10 * ==================================================== | |
| 11 */ | |
| 12 | |
| 13 #if defined(LIBM_SCCS) && !defined(lint) | |
| 14 static char rcsid[] = | |
| 15 "$NetBSD: s_floor.c,v 1.8 1995/05/10 20:47:20 jtc Exp $"; | |
| 16 #endif | |
| 17 | |
| 18 /* | |
| 19 * floor(x) | |
| 20 * Return x rounded toward -inf to integral value | |
| 21 * Method: | |
| 22 * Bit twiddling. | |
| 23 * Exception: | |
| 24 * Inexact flag raised if x not equal to floor(x). | |
| 25 */ | |
| 26 | |
| 27 #include "math.h" | |
| 28 #include "math_private.h" | |
| 29 | |
| 30 #ifdef __STDC__ | |
| 31 static const double huge = 1.0e300; | |
| 32 #else | |
| 33 static double huge = 1.0e300; | |
| 34 #endif | |
| 35 | |
| 36 libm_hidden_proto(floor) | |
| 37 #ifdef __STDC__ | |
| 38 double floor(double x) | |
| 39 #else | |
| 40 double floor(x) | |
| 41 double x; | |
| 42 #endif | |
| 43 { | |
| 44 int32_t i0, i1, j0; | |
| 45 u_int32_t i, j; | |
| 46 EXTRACT_WORDS(i0, i1, x); | |
| 47 j0 = ((i0 >> 20) & 0x7ff) - 0x3ff; | |
| 48 if (j0 < 20) { | |
| 49 if (j0 < 0) { /* raise inexact if x != 0 */ | |
| 50 if (huge + x > 0.0) { /* return 0*sign(x) if |x|<1 */ | |
| 51 if (i0 >= 0) { | |
| 52 i0 = i1 = 0; | |
| 53 } else if (((i0 & 0x7fffffff) | i1) != 0) { | |
| 54 i0 = 0xbff00000; | |
| 55 i1 = 0; | |
| 56 } | |
| 57 } | |
| 58 } else { | |
| 59 i = (0x000fffff) >> j0; | |
| 60 if (((i0 & i) | i1) == 0) | |
| 61 return x; /* x is integral */ | |
| 62 if (huge + x > 0.0) { /* raise inexact flag */ | |
| 63 if (i0 < 0) | |
| 64 i0 += (0x00100000) >> j0; | |
| 65 i0 &= (~i); | |
| 66 i1 = 0; | |
| 67 } | |
| 68 } | |
| 69 } else if (j0 > 51) { | |
| 70 if (j0 == 0x400) | |
| 71 return x + x; /* inf or NaN */ | |
| 72 else | |
| 73 return x; /* x is integral */ | |
| 74 } else { | |
| 75 i = ((u_int32_t) (0xffffffff)) >> (j0 - 20); | |
| 76 if ((i1 & i) == 0) | |
| 77 return x; /* x is integral */ | |
| 78 if (huge + x > 0.0) { /* raise inexact flag */ | |
| 79 if (i0 < 0) { | |
| 80 if (j0 == 20) | |
| 81 i0 += 1; | |
| 82 else { | |
| 83 j = i1 + (1 << (52 - j0)); | |
|
2765
f55c87ae336b
Final merge of Google Summer of Code 2008 work...
Sam Lantinga <slouken@libsdl.org>
parents:
2760
diff
changeset
|
84 if (j < (u_int32_t) i1) |
| 2758 | 85 i0 += 1; /* got a carry */ |
| 86 i1 = j; | |
| 87 } | |
| 88 } | |
| 89 i1 &= (~i); | |
| 90 } | |
| 91 } | |
| 92 INSERT_WORDS(x, i0, i1); | |
| 93 return x; | |
| 94 } | |
| 95 | |
| 96 libm_hidden_def(floor) |