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RenderDll/Common/Textures/Image/SHendian.h

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+#ifndef __SHENDIAN_H__
+#define __SHENDIAN_H__
+
+#define CS_LITTLE_ENDIAN
+/*
+ * This is a bit of overkill but if you're sure your CPU doesn't require
+ * strict alignment add your CPU to the !defined below to get slightly
+ * smaller and faster code in some cases.
+ */
+#if !defined (PROC_INTEL)
+#  define PROC_NEEDS_STRICT_ALIGNMENT
+#endif
+
+struct swap_4
+{
+  unsigned char b1, b2, b3, b4;
+};
+
+#ifdef CS_BIG_ENDIAN
+#  define big_endian_long(x)  x
+#  define big_endian_short(x) x
+#  define big_endian_float(x) x
+#else
+
+/// Convert a long from big-endian to machine format
+static inline unsigned long big_endian_long (unsigned long l)
+{ return (l >> 24) | ((l >> 8) & 0xff00) | ((l << 8) & 0xff0000) | (l << 24); }
+
+/// Convert a short from big-endian to machine format
+static inline ushort big_endian_short (ushort s)
+{ return (s >> 8) | (s << 8); }
+
+/// Convert a big-endian floating-point number to machine format
+//@@WARNING: Should be removed -- use float2long instead
+static inline float big_endian_float (float f)
+{
+  unsigned char tmp;
+  swap_4 *pf = (swap_4 *)&f;
+  tmp = pf->b1; pf->b1 = pf->b4; pf->b4 = tmp;
+  tmp = pf->b2; pf->b2 = pf->b3; pf->b3 = tmp;
+  return f;
+}
+
+#endif // CS_BIG_ENDIAN
+
+#ifdef CS_LITTLE_ENDIAN
+#  define little_endian_long(x)  x
+#  define little_endian_short(x) x
+#  define little_endian_float(x) x
+#else
+
+/// Convert a long from little-endian to machine format
+static inline unsigned long little_endian_long (unsigned long l)
+{ return (l >> 24) | ((l >> 8) & 0xff00) | ((l << 8) & 0xff0000) | (l << 24); }
+
+/// Convert a short from little-endian to machine format
+static inline ushort little_endian_short (ushort s)
+{ return (s >> 8) | (s << 8); }
+
+/// Convert a little-endian floating-point number to machine format
+static inline float little_endian_float (float f)
+{
+  unsigned char tmp;
+  swap_4 *pf = (swap_4 *)&f;
+  tmp = pf->b1; pf->b1 = pf->b4; pf->b4 = tmp;
+  tmp = pf->b2; pf->b2 = pf->b3; pf->b3 = tmp;
+  return f;
+}
+
+#endif // CS_LITTLE_ENDIAN
+
+/*
+    To be able to painlessly transfer files betwen platforms, we should
+    avoid using native floating-point format. Here are a couple of routines
+    that are guaranteed to work on all platforms.
+
+    The floating point is converted to a fixed 1.7.25 bits format
+    (one bit sign, 7 bits exponent, 25 bits mantissa) and back,
+    so that we can binary store floating-point number without
+    cross-platform problems. If you wonder why 1+7+25 = 33 while we
+    only have 32 bits, we'll ommit the most significant bit of mantissa
+    since it is always 1 (we use normalized numbers). This increases the
+    precision twice.
+*/
+
+/// Convert a float to a cross-platform 32-bit format (no endianess adjustments!)
+static inline long float2long (float f)
+{
+  int exp;
+  long mant = QRound ((float)frexp (f, &exp) * (float)0x1000000);
+  long sign = mant & 0x80000000;
+  if (mant < 0) mant = -mant;
+  if (exp > 63) exp = 63; else if (exp < -64) exp = -64;
+  return sign | ((exp & 0x7f) << 24) | (mant & 0xffffff);
+}
+
+/// Convert a 32-bit cross-platform float to native format (no endianess adjustments!)
+static inline float long2float (long l)
+{
+  int exp = (l >> 24) & 0x7f;
+  if (exp & 0x40) exp = exp | ~0x7f;
+  float mant = float (l & 0x00ffffff) / 0x1000000;
+  if (l & 0x80000000) mant = -mant;
+  return (float)ldexp (mant, exp);
+}
+
+/**
+ * The following routines are used for converting floating-point numbers
+ * into 16-bit shorts and back. This is useful for low-precision data.
+ * They use the 1.4.12 format. The range of numbers that can be represented
+ * in this format is from 2^-8 to 2^7. The precision for numbers near to
+ * 2^-8 (0.00390625) is near 0.000001, for numbers near 2^7 (128) is near 0.03.
+ */
+
+/// Convert a float to a cross-platform 16-bit format (no endianess adjustments!)
+static inline short float2short (float f)
+{
+  int exp;
+  long mant = QRound ((float)frexp (f, &exp) * (float)0x1000);
+  long sign = mant & 0x8000;
+  if (mant < 0) mant = -mant;
+  if (exp > 7) mant = 0x7ff, exp = 7; else if (exp < -8) mant = 0, exp = -8;
+  return (short)(sign | ((exp & 0xf) << 11) | (mant & 0x7ff));
+}
+
+/// Convert a 16-bit cross-platform float to native format (no endianess adjustments!)
+static inline float short2float (short s)
+{
+  int exp = (s >> 11) & 0xf;
+  if (exp & 0x8) exp = exp | ~0xf;
+  float mant = float ((s & 0x07ff) | 0x0800) / 0x1000;
+  if (s & 0x8000) mant = -mant;
+  return (float)ldexp (mant, exp);
+}
+
+/// Swap the bytes in a unsigned long value.
+static inline unsigned long convert_endian (unsigned long l)
+{ return little_endian_long (l); }
+
+/// Swap the bytes in a long value.
+static inline long convert_endian (long l)
+{ return little_endian_long (l); }
+
+/// Swap the bytes in a int value.
+static inline int convert_endian (int i)
+{ return little_endian_long (i); }
+
+/// Swap the bytes in a short value.
+static inline ushort convert_endian (ushort s)
+{ return little_endian_short (s); }
+
+/// Swap the bytes in a float value.
+static inline float convert_endian (float f)
+{ return little_endian_float (f); }
+
+/// Read a little-endian short from address
+inline ushort get_le_short (void *buff)
+{
+#ifdef PROC_NEEDS_STRICT_ALIGNMENT
+  ushort s; memcpy (&s, buff, sizeof (s));
+  return little_endian_short (s);
+#else
+  return little_endian_short (*(ushort *)buff);
+#endif
+}
+
+/// Read a little-endian long from address
+inline unsigned long get_le_long (void *buff)
+{
+#ifdef PROC_NEEDS_STRICT_ALIGNMENT
+  unsigned long l; memcpy (&l, buff, sizeof (l));
+  return little_endian_long (l);
+#else
+  return little_endian_long (*(unsigned long *)buff);
+#endif
+}
+
+/// Read a little-endian 32-bit float from address
+inline float get_le_float32 (void *buff)
+{ unsigned long l = get_le_long (buff); return long2float (l); }
+
+/// Read a little-endian 16-bit float from address
+inline float get_le_float16 (void *buff)
+{ ushort s = get_le_short (buff); return short2float (s); }
+
+/// Set a little-endian short on a address
+inline void set_le_short (void *buff, ushort s)
+{
+#ifdef PROC_NEEDS_STRICT_ALIGNMENT
+  s = little_endian_short (s);
+  memcpy (buff, &s, sizeof (s));
+#else
+  *((ushort *)buff) = little_endian_short (s);
+#endif
+}
+
+/// Set a little-endian long on a address
+inline void set_le_long (void *buff, unsigned long l)
+{
+#ifdef PROC_NEEDS_STRICT_ALIGNMENT
+  l = little_endian_long (l);
+  memcpy (buff, &l, sizeof (l));
+#else
+  *((unsigned long *)buff) = little_endian_long (l);
+#endif
+}
+
+/// Set a little-endian 32-bit float on a address
+inline void set_le_float32 (void *buff, float f)
+{ set_le_long (buff, float2long (f)); }
+
+/// Set a little-endian 16-bit float on a address
+inline void set_le_float16 (void *buff, float f)
+{ set_le_short (buff, float2short (f)); }
+
+#endif // __SHENDIAN_H__