1 /* 2 * ==================================================== 3 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 4 * 5 * Developed at SunPro, a Sun Microsystems, Inc. business. 6 * Permission to use, copy, modify, and distribute this 7 * software is freely granted, provided that this notice 8 * is preserved. 9 * ==================================================== 10 */ 11 12 /* 13 * from: @(#)fdlibm.h 5.1 93/09/24 14 * $Id$ 15 */ 16 17 #ifndef _MATH_PRIVATE_H_ 18 #define _MATH_PRIVATE_H_ 19 20 #include "SDL_name.h" 21 #include "SDL_endian.h" 22 23 #define huge really_big /* huge is a reserved keyword in VC++ 6.0 */ 24 #define u_int32_t uint32_t 25 26 /* The original fdlibm code used statements like: 27 n0 = ((*(int*)&one)>>29)^1; * index of high word * 28 ix0 = *(n0+(int*)&x); * high word of x * 29 ix1 = *((1-n0)+(int*)&x); * low word of x * 30 to dig two 32 bit words out of the 64 bit IEEE floating point 31 value. That is non-ANSI, and, moreover, the gcc instruction 32 scheduler gets it wrong. We instead use the following macros. 33 Unlike the original code, we determine the endianness at compile 34 time, not at run time; I don't see much benefit to selecting 35 endianness at run time. */ 36 37 /* A union which permits us to convert between a double and two 32 bit 38 ints. */ 39 40 /* 41 * Math on arm is special: 42 * For FPA, float words are always big-endian. 43 * For VFP, floats words follow the memory system mode. 44 */ 45 46 #if (SDL_BYTEORDER == SDL_BIG_ENDIAN) || \ 47 (!defined(__VFP_FP__) && (defined(__arm__) || defined(__thumb__))) 48 49 typedef union 50 { 51 double value; 52 struct 53 { 54 u_int32_t msw; 55 u_int32_t lsw; 56 } parts; 57 } ieee_double_shape_type; 58 59 #else 60 61 typedef union 62 { 63 double value; 64 struct 65 { 66 u_int32_t lsw; 67 u_int32_t msw; 68 } parts; 69 } ieee_double_shape_type; 70 71 #endif 72 73 /* Get two 32 bit ints from a double. */ 74 75 #define EXTRACT_WORDS(ix0,ix1,d) \ 76 do { \ 77 ieee_double_shape_type ew_u; \ 78 ew_u.value = (d); \ 79 (ix0) = ew_u.parts.msw; \ 80 (ix1) = ew_u.parts.lsw; \ 81 } while (0) 82 83 /* Get the more significant 32 bit int from a double. */ 84 85 #define GET_HIGH_WORD(i,d) \ 86 do { \ 87 ieee_double_shape_type gh_u; \ 88 gh_u.value = (d); \ 89 (i) = gh_u.parts.msw; \ 90 } while (0) 91 92 /* Get the less significant 32 bit int from a double. */ 93 94 #define GET_LOW_WORD(i,d) \ 95 do { \ 96 ieee_double_shape_type gl_u; \ 97 gl_u.value = (d); \ 98 (i) = gl_u.parts.lsw; \ 99 } while (0) 100 101 /* Set a double from two 32 bit ints. */ 102 103 #define INSERT_WORDS(d,ix0,ix1) \ 104 do { \ 105 ieee_double_shape_type iw_u; \ 106 iw_u.parts.msw = (ix0); \ 107 iw_u.parts.lsw = (ix1); \ 108 (d) = iw_u.value; \ 109 } while (0) 110 111 /* Set the more significant 32 bits of a double from an int. */ 112 113 #define SET_HIGH_WORD(d,v) \ 114 do { \ 115 ieee_double_shape_type sh_u; \ 116 sh_u.value = (d); \ 117 sh_u.parts.msw = (v); \ 118 (d) = sh_u.value; \ 119 } while (0) 120 121 /* Set the less significant 32 bits of a double from an int. */ 122 123 #define SET_LOW_WORD(d,v) \ 124 do { \ 125 ieee_double_shape_type sl_u; \ 126 sl_u.value = (d); \ 127 sl_u.parts.lsw = (v); \ 128 (d) = sl_u.value; \ 129 } while (0) 130 131 /* A union which permits us to convert between a float and a 32 bit 132 int. */ 133 134 typedef union 135 { 136 float value; 137 u_int32_t word; 138 } ieee_float_shape_type; 139 140 /* Get a 32 bit int from a float. */ 141 142 #define GET_FLOAT_WORD(i,d) \ 143 do { \ 144 ieee_float_shape_type gf_u; \ 145 gf_u.value = (d); \ 146 (i) = gf_u.word; \ 147 } while (0) 148 149 /* Set a float from a 32 bit int. */ 150 151 #define SET_FLOAT_WORD(d,i) \ 152 do { \ 153 ieee_float_shape_type sf_u; \ 154 sf_u.word = (i); \ 155 (d) = sf_u.value; \ 156 } while (0) 157 158 159 #ifdef __STDC__ 160 static const double 161 #else 162 static double 163 #endif 164 zero = 0.0, 165 one = 1.0, 166 two = 2.0, 167 two53 = 9007199254740992.0, /* 0x43400000, 0x00000000 */ 168 two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */ 169 twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */ 170 huge = 1.0e+300, 171 tiny = 1.0e-300; 172 173 #endif /* _MATH_PRIVATE_H_ */ 174
