| cc68a136 |
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: math_private.h,v 1.3 2004/02/09 07:10:38 andersen Exp $ |
| 15 | */ |
| 16 | |
| 17 | #ifndef _MATH_PRIVATE_H_ |
| 18 | #define _MATH_PRIVATE_H_ |
| 19 | |
| 20 | #include <endian.h> |
| 21 | #include <sys/types.h> |
| 22 | |
| 23 | /* The original fdlibm code used statements like: |
| 24 | n0 = ((*(int*)&one)>>29)^1; * index of high word * |
| 25 | ix0 = *(n0+(int*)&x); * high word of x * |
| 26 | ix1 = *((1-n0)+(int*)&x); * low word of x * |
| 27 | to dig two 32 bit words out of the 64 bit IEEE floating point |
| 28 | value. That is non-ANSI, and, moreover, the gcc instruction |
| 29 | scheduler gets it wrong. We instead use the following macros. |
| 30 | Unlike the original code, we determine the endianness at compile |
| 31 | time, not at run time; I don't see much benefit to selecting |
| 32 | endianness at run time. */ |
| 33 | |
| 34 | /* A union which permits us to convert between a double and two 32 bit |
| 35 | ints. */ |
| 36 | |
| 37 | /* |
| 38 | * Math on arm is special: |
| 39 | * For FPA, float words are always big-endian. |
| 40 | * For VFP, floats words follow the memory system mode. |
| 41 | */ |
| 42 | |
| 43 | #if (__BYTE_ORDER == __BIG_ENDIAN) || \ |
| 44 | (!defined(__VFP_FP__) && (defined(__arm__) || defined(__thumb__))) |
| 45 | |
| 46 | typedef union |
| 47 | { |
| 48 | double value; |
| 49 | struct |
| 50 | { |
| 51 | u_int32_t msw; |
| 52 | u_int32_t lsw; |
| 53 | } parts; |
| 54 | } ieee_double_shape_type; |
| 55 | |
| 56 | #else |
| 57 | |
| 58 | typedef union |
| 59 | { |
| 60 | double value; |
| 61 | struct |
| 62 | { |
| 63 | u_int32_t lsw; |
| 64 | u_int32_t msw; |
| 65 | } parts; |
| 66 | } ieee_double_shape_type; |
| 67 | |
| 68 | #endif |
| 69 | |
| 70 | /* Get two 32 bit ints from a double. */ |
| 71 | |
| 72 | #define EXTRACT_WORDS(ix0,ix1,d) \ |
| 73 | do { \ |
| 74 | ieee_double_shape_type ew_u; \ |
| 75 | ew_u.value = (d); \ |
| 76 | (ix0) = ew_u.parts.msw; \ |
| 77 | (ix1) = ew_u.parts.lsw; \ |
| 78 | } while (0) |
| 79 | |
| 80 | /* Get the more significant 32 bit int from a double. */ |
| 81 | |
| 82 | #define GET_HIGH_WORD(i,d) \ |
| 83 | do { \ |
| 84 | ieee_double_shape_type gh_u; \ |
| 85 | gh_u.value = (d); \ |
| 86 | (i) = gh_u.parts.msw; \ |
| 87 | } while (0) |
| 88 | |
| 89 | /* Get the less significant 32 bit int from a double. */ |
| 90 | |
| 91 | #define GET_LOW_WORD(i,d) \ |
| 92 | do { \ |
| 93 | ieee_double_shape_type gl_u; \ |
| 94 | gl_u.value = (d); \ |
| 95 | (i) = gl_u.parts.lsw; \ |
| 96 | } while (0) |
| 97 | |
| 98 | /* Set a double from two 32 bit ints. */ |
| 99 | |
| 100 | #define INSERT_WORDS(d,ix0,ix1) \ |
| 101 | do { \ |
| 102 | ieee_double_shape_type iw_u; \ |
| 103 | iw_u.parts.msw = (ix0); \ |
| 104 | iw_u.parts.lsw = (ix1); \ |
| 105 | (d) = iw_u.value; \ |
| 106 | } while (0) |
| 107 | |
| 108 | /* Set the more significant 32 bits of a double from an int. */ |
| 109 | |
| 110 | #define SET_HIGH_WORD(d,v) \ |
| 111 | do { \ |
| 112 | ieee_double_shape_type sh_u; \ |
| 113 | sh_u.value = (d); \ |
| 114 | sh_u.parts.msw = (v); \ |
| 115 | (d) = sh_u.value; \ |
| 116 | } while (0) |
| 117 | |
| 118 | /* Set the less significant 32 bits of a double from an int. */ |
| 119 | |
| 120 | #define SET_LOW_WORD(d,v) \ |
| 121 | do { \ |
| 122 | ieee_double_shape_type sl_u; \ |
| 123 | sl_u.value = (d); \ |
| 124 | sl_u.parts.lsw = (v); \ |
| 125 | (d) = sl_u.value; \ |
| 126 | } while (0) |
| 127 | |
| 128 | |
| 129 | #endif /* _MATH_PRIVATE_H_ */ |
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