| /* |
| * 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 |
| |
| #include "drirenderbuffer.h" |
| |
| |
| extern void savageDDInitSpanFuncs( GLcontext *ctx ); |
| |
| extern void |
| savageSetSpanFunctions(driRenderbuffer *rb, const GLvisual *vis, |
| GLboolean float_depth); |
| |
| |
| /* |
| * 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 |