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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 1969 2006-02-24 09:57:14Z slouken $
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