diff src/video/math_private.h @ 1330:450721ad5436

It's now possible to build SDL without any C runtime at all on Windows, using Visual C++ 2005
author Sam Lantinga <slouken@libsdl.org>
date Mon, 06 Feb 2006 08:28:51 +0000
parents
children 62802d9d7c87
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/video/math_private.h	Mon Feb 06 08:28:51 2006 +0000
@@ -0,0 +1,172 @@
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+/*
+ * from: @(#)fdlibm.h 5.1 93/09/24
+ * $Id$
+ */
+
+#ifndef _MATH_PRIVATE_H_
+#define _MATH_PRIVATE_H_
+
+#include "SDL_endian.h"
+
+typedef Sint32 int32_t;
+typedef Uint32 u_int32_t;
+
+/* The original fdlibm code used statements like:
+	n0 = ((*(int*)&one)>>29)^1;		* index of high word *
+	ix0 = *(n0+(int*)&x);			* high word of x *
+	ix1 = *((1-n0)+(int*)&x);		* low word of x *
+   to dig two 32 bit words out of the 64 bit IEEE floating point
+   value.  That is non-ANSI, and, moreover, the gcc instruction
+   scheduler gets it wrong.  We instead use the following macros.
+   Unlike the original code, we determine the endianness at compile
+   time, not at run time; I don't see much benefit to selecting
+   endianness at run time.  */
+
+/* A union which permits us to convert between a double and two 32 bit
+   ints.  */
+
+/*
+ * Math on arm is special:
+ * For FPA, float words are always big-endian.
+ * For VFP, floats words follow the memory system mode.
+ */
+
+#if (SDL_BYTEORDER == SDL_BIG_ENDIAN) || \
+    (!defined(__VFP_FP__) && (defined(__arm__) || defined(__thumb__)))
+
+typedef union
+{
+  double value;
+  struct
+  {
+    u_int32_t msw;
+    u_int32_t lsw;
+  } parts;
+} ieee_double_shape_type;
+
+#else
+
+typedef union
+{
+  double value;
+  struct
+  {
+    u_int32_t lsw;
+    u_int32_t msw;
+  } parts;
+} ieee_double_shape_type;
+
+#endif
+
+/* Get two 32 bit ints from a double.  */
+
+#define EXTRACT_WORDS(ix0,ix1,d)				\
+do {								\
+  ieee_double_shape_type ew_u;					\
+  ew_u.value = (d);						\
+  (ix0) = ew_u.parts.msw;					\
+  (ix1) = ew_u.parts.lsw;					\
+} while (0)
+
+/* Get the more significant 32 bit int from a double.  */
+
+#define GET_HIGH_WORD(i,d)					\
+do {								\
+  ieee_double_shape_type gh_u;					\
+  gh_u.value = (d);						\
+  (i) = gh_u.parts.msw;						\
+} while (0)
+
+/* Get the less significant 32 bit int from a double.  */
+
+#define GET_LOW_WORD(i,d)					\
+do {								\
+  ieee_double_shape_type gl_u;					\
+  gl_u.value = (d);						\
+  (i) = gl_u.parts.lsw;						\
+} while (0)
+
+/* Set a double from two 32 bit ints.  */
+
+#define INSERT_WORDS(d,ix0,ix1)					\
+do {								\
+  ieee_double_shape_type iw_u;					\
+  iw_u.parts.msw = (ix0);					\
+  iw_u.parts.lsw = (ix1);					\
+  (d) = iw_u.value;						\
+} while (0)
+
+/* Set the more significant 32 bits of a double from an int.  */
+
+#define SET_HIGH_WORD(d,v)					\
+do {								\
+  ieee_double_shape_type sh_u;					\
+  sh_u.value = (d);						\
+  sh_u.parts.msw = (v);						\
+  (d) = sh_u.value;						\
+} while (0)
+
+/* Set the less significant 32 bits of a double from an int.  */
+
+#define SET_LOW_WORD(d,v)					\
+do {								\
+  ieee_double_shape_type sl_u;					\
+  sl_u.value = (d);						\
+  sl_u.parts.lsw = (v);						\
+  (d) = sl_u.value;						\
+} while (0)
+
+/* A union which permits us to convert between a float and a 32 bit
+   int.  */
+
+typedef union
+{
+  float value;
+  u_int32_t word;
+} ieee_float_shape_type;
+
+/* Get a 32 bit int from a float.  */
+
+#define GET_FLOAT_WORD(i,d)					\
+do {								\
+  ieee_float_shape_type gf_u;					\
+  gf_u.value = (d);						\
+  (i) = gf_u.word;						\
+} while (0)
+
+/* Set a float from a 32 bit int.  */
+
+#define SET_FLOAT_WORD(d,i)					\
+do {								\
+  ieee_float_shape_type sf_u;					\
+  sf_u.word = (i);						\
+  (d) = sf_u.value;						\
+} while (0)
+
+
+#ifdef __STDC__
+static const double
+#else
+static double
+#endif
+zero    =  0.0,
+one	=  1.0,
+two	=  2.0,
+two53	=  9007199254740992.0,	/* 0x43400000, 0x00000000 */
+two54   =  1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
+twom54  =  5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
+huge   = 1.0e+300,
+tiny   = 1.0e-300;
+
+#endif /* _MATH_PRIVATE_H_ */