src/video/math_private.h
author Ozkan Sezer <sezeroz@gmail.com>
Sun, 14 Oct 2018 15:25:04 +0300
branchSDL-1.2
changeset 12325 c4f2eeda176f
parent 1424 7a610f25c12f
child 1662 782fd950bd46
permissions -rw-r--r--
remove symlink for libSDL-1.0.so.0 from the rpm spec file.

also fix a changelog date.
     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_ */