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SPU: 

- Improve performance of cosine interpolation (making it as fast as linear).
This commit is contained in:
rogerman 2012-01-18 04:25:49 +00:00
parent 09985b15a8
commit 4f4704b486
1 changed files with 29 additions and 18 deletions
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47
desmume/src/SPU.cpp
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@ -1,7 +1,7 @@
/* SPU.cpp /* SPU.cpp
Copyright (C) 2006 yopyop Copyright (C) 2006 yopyop
Copyright (C) 2006 Theo Berkau Copyright (C) 2006 Theo Berkau
Copyright (C) 2008-2010 DeSmuME team Copyright (C) 2008-2012 DeSmuME team
Ideas borrowed from Stephane Dallongeville's SCSP core Ideas borrowed from Stephane Dallongeville's SCSP core
@ -45,6 +45,7 @@
#include "metaspu/metaspu.h" #include "metaspu/metaspu.h"
#define K_ADPCM_LOOPING_RECOVERY_INDEX 99999 #define K_ADPCM_LOOPING_RECOVERY_INDEX 99999
#define COSINE_INTERPOLATION_RESOLUTION 8192
//#ifdef FASTBUILD //#ifdef FASTBUILD
#undef FORCEINLINE #undef FORCEINLINE
@ -103,6 +104,7 @@ static const s16 wavedutytbl[8][8] = {
static s32 precalcdifftbl[89][16]; static s32 precalcdifftbl[89][16];
static u8 precalcindextbl[89][8]; static u8 precalcindextbl[89][8];
static double cos_lut[COSINE_INTERPOLATION_RESOLUTION];
static const double ARM7_CLOCK = 33513982; static const double ARM7_CLOCK = 33513982;
@ -186,14 +188,13 @@ void SPU_ReInit()
SPU_Init(SNDCoreId, buffersize); SPU_Init(SNDCoreId, buffersize);
} }
//static double cos_lut[256];
int SPU_Init(int coreid, int buffersize) int SPU_Init(int coreid, int buffersize)
{ {
int i, j; int i, j;
//for some reason we dont use the cos lut anymore... did someone decide it was slow? // Build the cosine interpolation LUT
//for(int i=0;i<256;i++) for(unsigned int i = 0; i < COSINE_INTERPOLATION_RESOLUTION; i++)
// cos_lut[i] = cos(i/256.0*M_PI); cos_lut[i] = (1.0 - cos(((double)i/(double)COSINE_INTERPOLATION_RESOLUTION) * M_PI)) * 0.5;
SPU_core = new SPU_struct((int)ceil(samples_per_hline)); SPU_core = new SPU_struct((int)ceil(samples_per_hline));
SPU_Reset(); SPU_Reset();
@ -795,20 +796,30 @@ void SPU_WriteLong(u32 addr, u32 val)
template<SPUInterpolationMode INTERPOLATE_MODE> static FORCEINLINE s32 Interpolate(s32 a, s32 b, double ratio) template<SPUInterpolationMode INTERPOLATE_MODE> static FORCEINLINE s32 Interpolate(s32 a, s32 b, double ratio)
{ {
if(INTERPOLATE_MODE == SPUInterpolation_Cosine) double sampleA = (double)a;
double sampleB = (double)b;
ratio = ratio - sputrunc(ratio);
switch (INTERPOLATE_MODE)
{ {
//why did we change it away from the lookup table? somebody should research that case SPUInterpolation_Cosine:
ratio = ratio - sputrunc(ratio); // Cosine Interpolation Formula:
double ratio2 = ((1.0 - cos(ratio * M_PI)) * 0.5); // ratio2 = (1 - cos(ratio * M_PI)) / 2
//double ratio2 = (1.0f - cos_lut[((int)(ratio*256.0))&0xFF]) / 2.0f; // sampleI = sampleA * (1 - ratio2) + sampleB * ratio2
return s32floor((float)(((1-ratio2)*a) + (ratio2*b))); return s32floor((cos_lut[(unsigned int)(ratio * (double)COSINE_INTERPOLATION_RESOLUTION)] * (sampleB - sampleA)) + sampleA);
} break;
else
{ case SPUInterpolation_Linear:
//linear interpolation // Linear Interpolation Formula:
ratio = ratio - sputrunc(ratio); // sampleI = sampleA * (1 - ratio) + sampleB * ratio
return s32floor((float)((1-ratio)*a + ratio*b)); return s32floor((ratio * (sampleB - sampleA)) + sampleA);
break;
default:
break;
} }
return a;
} }
////////////////////////////////////////////////////////////////////////////// //////////////////////////////////////////////////////////////////////////////