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/*
* Copyright 1998-2003 VIA Technologies, Inc. All Rights Reserved.
* Copyright 2001-2003 S3 Graphics, Inc. All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sub license,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial portions
* of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
* VIA, S3 GRAPHICS, AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
#ifndef _SAVAGE_SPAN_H
#define _SAVAGE_SPAN_H
extern void savageDDInitSpanFuncs( GLcontext *ctx );
/*
* Savage 16-bit float depth format with zExpOffset=16:
* 4 bit unsigned exponent, 12 bit mantissa
*
* The meaning of the mantissa is different from IEEE floatint point
* formats. The same number can't be encoded with different exponents.
* So no bits are wasted.
*
* exponent | range encoded by mantissa | accuracy or mantissa
* ---------+---------------------------+---------------------
* 15 | 2^-1 .. 1 | 2^-13
* 14 | 2^-2 .. 2^-1 | 2^-14
* 13 | 2^-3 .. 2^-2 | 2^-15
* ... | ... |
* 2 | 2^-14 .. 2^-13 | 2^-27
* 1 | 2^-15 .. 2^-14 | 2^-27
* 0 | 2^-16 .. 2^-15 | 2^-28
*
* Note that there is no encoding for numbers < 2^-16.
*/
static __inline GLuint savageEncodeFloat16( GLdouble x )
{
GLint r = (GLint)(x * 0x10000000);
GLint exp = 0;
if (r < 0x1000)
return 0;
while (r - 0x1000 > 0x0fff) {
r >>= 1;
exp++;
}
return exp > 0xf ? 0xffff : (r - 0x1000) | (exp << 12);
}
static __inline GLdouble savageDecodeFloat16( GLuint x )
{
static const GLdouble pow2[16] = {
1.0/(1<<28), 1.0/(1<<27), 1.0/(1<<26), 1.0/(1<<25),
1.0/(1<<24), 1.0/(1<<23), 1.0/(1<<22), 1.0/(1<<21),
1.0/(1<<20), 1.0/(1<<19), 1.0/(1<<18), 1.0/(1<<17),
1.0/(1<<16), 1.0/(1<<15), 1.0/(1<<14), 1.0/(1<<13)
};
static const GLdouble bias[16] = {
1.0/(1<<16), 1.0/(1<<15), 1.0/(1<<14), 1.0/(1<<13),
1.0/(1<<12), 1.0/(1<<11), 1.0/(1<<10), 1.0/(1<< 9),
1.0/(1<< 8), 1.0/(1<< 7), 1.0/(1<< 6), 1.0/(1<< 5),
1.0/(1<< 4), 1.0/(1<< 3), 1.0/(1<< 2), 1.0/(1<< 1)
};
GLuint mant = x & 0x0fff;
GLuint exp = (x >> 12) & 0xf;
return bias[exp] + pow2[exp]*mant;
}
/*
* Savage 24-bit float depth format with zExpOffset=32:
* 5 bit unsigned exponent, 19 bit mantissa
*
* Details analogous to the 16-bit format.
*/
static __inline GLuint savageEncodeFloat24( GLdouble x )
{
int64_t r = (int64_t)(x * ((int64_t)1 << (19+32)));
GLint exp = 0;
if (r < 0x80000)
return 0;
while (r - 0x80000 > 0x7ffff) {
r >>= 1;
exp++;
}
return exp > 0x1f ? 0xffffff : (r - 0x80000) | (exp << 19);
}
#define _1 (int64_t)1
static __inline GLdouble savageDecodeFloat24( GLuint x )
{
static const GLdouble pow2[32] = {
1.0/(_1<<51), 1.0/(_1<<50), 1.0/(_1<<49), 1.0/(_1<<48),
1.0/(_1<<47), 1.0/(_1<<46), 1.0/(_1<<45), 1.0/(_1<<44),
1.0/(_1<<43), 1.0/(_1<<42), 1.0/(_1<<41), 1.0/(_1<<40),
1.0/(_1<<39), 1.0/(_1<<38), 1.0/(_1<<37), 1.0/(_1<<36),
1.0/(_1<<35), 1.0/(_1<<34), 1.0/(_1<<33), 1.0/(_1<<32),
1.0/(_1<<31), 1.0/(_1<<30), 1.0/(_1<<29), 1.0/(_1<<28),
1.0/(_1<<27), 1.0/(_1<<26), 1.0/(_1<<25), 1.0/(_1<<24),
1.0/(_1<<23), 1.0/(_1<<22), 1.0/(_1<<21), 1.0/(_1<<20)
};
static const GLdouble bias[32] = {
1.0/(_1<<32), 1.0/(_1<<31), 1.0/(_1<<30), 1.0/(_1<<29),
1.0/(_1<<28), 1.0/(_1<<27), 1.0/(_1<<26), 1.0/(_1<<25),
1.0/(_1<<24), 1.0/(_1<<23), 1.0/(_1<<22), 1.0/(_1<<21),
1.0/(_1<<20), 1.0/(_1<<19), 1.0/(_1<<18), 1.0/(_1<<17),
1.0/(_1<<16), 1.0/(_1<<15), 1.0/(_1<<14), 1.0/(_1<<13),
1.0/(_1<<12), 1.0/(_1<<11), 1.0/(_1<<10), 1.0/(_1<< 9),
1.0/(_1<< 8), 1.0/(_1<< 7), 1.0/(_1<< 6), 1.0/(_1<< 5),
1.0/(_1<< 4), 1.0/(_1<< 3), 1.0/(_1<< 2), 1.0/(_1<< 1)
};
GLuint mant = x & 0x7ffff;
GLuint exp = (x >> 19) & 0x1f;
return bias[exp] + pow2[exp]*mant;
}
#undef _1
#endif
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