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/**************************************************************************
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Copyright 2000 Silicon Integrated Systems Corp, Inc., HsinChu, Taiwan.
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Copyright 2003 Eric Anholt
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Permission is hereby granted, free of charge, to any person obtaining a
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copy of this software and associated documentation files (the "Software"),
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to deal in the Software without restriction, including without limitation
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on the rights to use, copy, modify, merge, publish, distribute, sub
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license, and/or sell copies of the Software, and to permit persons to whom
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the Software is furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice (including the next
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paragraph) shall be included in all copies or substantial portions of the
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
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ERIC ANHOLT OR SILICON INTEGRATED SYSTEMS CORP BE LIABLE FOR ANY CLAIM,
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DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
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OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
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USE OR OTHER DEALINGS IN THE SOFTWARE.
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**************************************************************************/
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* Sung-Ching Lin <sclin@sis.com.tw>
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* Eric Anholt <anholt@FreeBSD.org>
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#include "sis_context.h"
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#include "sis_state.h"
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#include "swrast/swrast.h"
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#include "main/macros.h"
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static GLint convertFtToFogFt( GLfloat dwInValue );
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static GLint doFPtoFixedNoRound( GLfloat dwInValue, int nFraction );
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sisDDFogfv( GLcontext *ctx, GLenum pname, const GLfloat *params )
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sisContextPtr smesa = SIS_CONTEXT(ctx);
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__GLSiSHardware *prev = &smesa->prev;
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__GLSiSHardware *current = &smesa->current;
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case GL_FOG_COORDINATE_SOURCE_EXT:
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current->hwFog &= ~MASK_FogMode;
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switch (ctx->Fog.FogCoordinateSource)
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case GL_FOG_COORDINATE_EXT:
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current->hwFog &= ~MASK_FogZLookup;
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case GL_FRAGMENT_DEPTH_EXT:
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current->hwFog |= MASK_FogZLookup;
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if (current->hwFog != prev->hwFog) {
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prev->hwFog = current->hwFog;
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smesa->GlobalFlag |= GFLAG_FOGSETTING;
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current->hwFog &= ~MASK_FogMode;
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switch (ctx->Fog.Mode)
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current->hwFog |= FOGMODE_LINEAR;
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current->hwFog |= FOGMODE_EXP;
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current->hwFog |= FOGMODE_EXP2;
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if (current->hwFog != prev->hwFog) {
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prev->hwFog = current->hwFog;
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smesa->GlobalFlag |= GFLAG_FOGSETTING;
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current->hwFogDensity = convertFtToFogFt( ctx->Fog.Density );
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if (current->hwFogDensity != prev->hwFogDensity) {
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prev->hwFogDensity = current->hwFogDensity;
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smesa->GlobalFlag |= GFLAG_FOGSETTING;
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fArg = 1.0 / (ctx->Fog.End - ctx->Fog.Start);
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current->hwFogInverse = doFPtoFixedNoRound( fArg, 10 );
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if (pname == GL_FOG_END)
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if (smesa->Chipset == PCI_CHIP_SIS300)
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current->hwFogFar = doFPtoFixedNoRound( ctx->Fog.End, 10 );
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current->hwFogFar = doFPtoFixedNoRound( ctx->Fog.End, 6 );
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if (current->hwFogFar != prev->hwFogFar ||
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current->hwFogInverse != prev->hwFogInverse)
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prev->hwFogFar = current->hwFogFar;
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prev->hwFogInverse = current->hwFogInverse;
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smesa->GlobalFlag |= GFLAG_FOGSETTING;
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fogColor = FLOAT_TO_UBYTE( ctx->Fog.Color[0] ) << 16;
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fogColor |= FLOAT_TO_UBYTE( ctx->Fog.Color[1] ) << 8;
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fogColor |= FLOAT_TO_UBYTE( ctx->Fog.Color[2] );
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current->hwFog &= 0xff000000;
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current->hwFog |= fogColor;
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if (current->hwFog != prev->hwFog) {
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prev->hwFog = current->hwFog;
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smesa->GlobalFlag |= GFLAG_FOGSETTING;
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doFPtoFixedNoRound( GLfloat dwInValue, int nFraction )
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union { int i; float f; } u;
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nTemp = (int) (val & 0x7F800000) >> 23;
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nTemp = nTemp - 127 + nFraction - 23;
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dwMantissa = (val & 0x007FFFFF) | 0x00800000;
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dwMantissa <<= nTemp;
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dwMantissa >>= nTemp;
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if (val & 0x80000000)
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dwMantissa = ~dwMantissa + 1;
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/* s[8].23->s[7].10 */
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convertFtToFogFt( GLfloat dwInValue )
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GLint dwMantissa, dwExp;
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union { int i; float f; } u;
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/* ----- Standard float Format: s[8].23 -----
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* ----- = (-1)^S * 2^(E - 127) * (1 + M / 2^23) -----
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* ----- = (-1)^S * 2^((E-63) - 64) * (1 + (M/2^13) / 2^10) -----
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* ----- Density float Format: s[7].10 -----
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* ----- New Exponential = E - 63 -----
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* ----- New Mantissa = M / 2^13 -----
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dwExp = (val & 0x7F800000) >> 23;
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dwMantissa = (val & 0x007FFFFF) >> (23 - 10);
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/* ----- To Return +Max(or -Max) ----- */
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dwRet = (val & 0x80000000) >> (31 - 17); /* Shift Sign Bit */
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dwRet |= (dwExp << 10) | dwMantissa;