shithub: pt2-clone

--- a/src/pt2_ledfilter.c

+++ /dev/null

@@ -1,46 +1,0 @@

-/* Biquad low-pass filter with resonance, from:

-** https://www.musicdsp.org/en/latest/Filters/38-lp-and-hp-filter.html

-*/

-#include "pt2_ledfilter.h"

-#include "pt2_math.h"

-void clearLEDFilterState(ledFilter_t *f)

-{

-	f->LIn1 = f->LIn2 = f->LOut1 = f->LOut2 = 0.0;

-	f->RIn1 = f->RIn2 = f->ROut1 = f->ROut2 = 0.0;

-}

-void calcLEDFilterCoeffs(double sr, double hz, double qfactor, ledFilter_t *filter)

-{

-	const double c = 1.0 / pt2_tan((PT2_PI * hz) / sr);

-	const double r = 1.0 / qfactor;

-	filter->a1 = 1.0 / (1.0 + r * c + c * c);

-	filter->a2 = 2.0 * filter->a1;

-	filter->a3 = filter->a1;

-	filter->b1 = 2.0 * (1.0 - c*c) * filter->a1;

-	filter->b2 = (1.0 - r * c + c * c) * filter->a1;

-}

-void LEDFilter(ledFilter_t *f, const double *in, double *out)

-{

-	const double LOut = (f->a1 * in[0]) + (f->a2 * f->LIn1) + (f->a3 * f->LIn2) - (f->b1 * f->LOut1) - (f->b2 * f->LOut2);

-	const double ROut = (f->a1 * in[1]) + (f->a2 * f->RIn1) + (f->a3 * f->RIn2) - (f->b1 * f->ROut1) - (f->b2 * f->ROut2);

-	// shift states

-	f->LIn2 = f->LIn1;

-	f->LIn1 = in[0];

-	f->LOut2 = f->LOut1;

-	f->LOut1 = LOut;

-	f->RIn2 = f->RIn1;

-	f->RIn1 = in[1];

-	f->ROut2 = f->ROut1;

-	f->ROut1 = ROut;

-	// set output

-	out[0] = LOut;

-	out[1] = ROut;

-}

--- a/src/pt2_ledfilter.h

+++ /dev/null

@@ -1,15 +1,0 @@

-#pragma once

-#include <stdint.h>

-#include <stdbool.h>

-typedef struct ledFilter_t

-{

-	double LIn1, LIn2, LOut1, LOut2;

-	double RIn1, RIn2, ROut1, ROut2;

-	double a1, a2, a3, b1, b2;

-} ledFilter_t;

-void clearLEDFilterState(ledFilter_t *f);

-void calcLEDFilterCoeffs(double sr, double hz, double qfactor, ledFilter_t *filter);

-void LEDFilter(ledFilter_t *f, const double *in, double *out);

--- a/src/pt2_paula.c

+++ b/src/pt2_paula.c

@@ -9,8 +9,7 @@

 #include <stdbool.h>

 #include "pt2_paula.h"

 #include "pt2_blep.h"

-#include "pt2_rcfilter.h"

-#include "pt2_ledfilter.h"

+#include "pt2_rcfilters.h"

 #include "pt2_math.h"

 typedef struct voice_t

@@ -40,8 +39,8 @@

 static int8_t nullSample[0xFFFF*2]; // buffer for NULL data pointer

 static double dPaulaOutputFreq, dPeriodToDeltaDiv;

 static blep_t blep[PAULA_VOICES];

-static rcFilter_t filterLo, filterHi;

-static ledFilter_t filterLED;

+static onePoleFilter_t filterLo, filterHi;

+static twoPoleFilter_t filterLED;

 static paulaVoice_t paula[PAULA_VOICES];

 void paulaSetup(double dOutputFreq, uint32_t amigaModel)

@@ -53,9 +52,9 @@

 	dPeriodToDeltaDiv = PAULA_PAL_CLK / dPaulaOutputFreq;

 	useLowpassFilter = useHighpassFilter = true;

-	clearRCFilterState(&filterLo);

-	clearRCFilterState(&filterHi);

-	clearLEDFilterState(&filterLED);

+	clearOnePoleFilterState(&filterLo);

+	clearOnePoleFilterState(&filterHi);

+	clearTwoPoleFilterState(&filterLED);

 	/* Amiga 500/1200 filter emulation

**

@@ -111,17 +110,17 @@

 	if (amigaModel == MODEL_A500)

-		// A500 1-pole (6db/oct) static RC low-pass filter:

+		// A500 1-pole (6db/oct) RC low-pass filter:

 		R = 360.0; // R321 (360 ohm)

 		C = 1e-7;  // C321 (0.1uF)

 		cutoff = 1.0 / (PT2_TWO_PI * R * C); // ~4420.971Hz

-		calcRCFilterCoeffs(dPaulaOutputFreq, cutoff, &filterLo);

+		setupOnePoleFilter(dPaulaOutputFreq, cutoff, &filterLo);

-		// A500 1-pole (6dB/oct) static RC high-pass filter:

+		// A500 1-pole (6dB/oct) RC high-pass filter:

 		R = 1390.0;   // R324 (1K ohm) + R325 (390 ohm)

 		C = 2.233e-5; // C334 (22uF) + C335 (0.33uF)

 		cutoff = 1.0 / (PT2_TWO_PI * R * C); // ~5.128Hz

-		calcRCFilterCoeffs(dPaulaOutputFreq, cutoff, &filterHi);

+		setupOnePoleFilter(dPaulaOutputFreq, cutoff, &filterHi);

 	else

@@ -132,14 +131,14 @@

*/

 		useLowpassFilter = false;

-		// A1200 1-pole (6dB/oct) static RC high-pass filter:

+		// A1200 1-pole (6dB/oct) RC high-pass filter:

 		R = 1360.0; // R324 (1K ohm resistor) + R325 (360 ohm resistor)

 		C = 2.2e-5; // C334 (22uF capacitor)

 		cutoff = 1.0 / (PT2_TWO_PI * R * C); // ~5.319Hz

-		calcRCFilterCoeffs(dPaulaOutputFreq, cutoff, &filterHi);

+		setupOnePoleFilter(dPaulaOutputFreq, cutoff, &filterHi);

-	// Sallen-Key low-pass filter ("LED" filter, same values on A500/A1200):

+	// 2-pole (12dB/oct) RC low-pass filter ("LED" filter, same values on A500/A1200):

 	R1 = 10000.0; // R322 (10K ohm)

 	R2 = 10000.0; // R323 (10K ohm)

 	C1 = 6.8e-9;  // C322 (6800pF)

@@ -146,7 +145,7 @@

 	C2 = 3.9e-9;  // C323 (3900pF)

 	cutoff = 1.0 / (PT2_TWO_PI * pt2_sqrt(R1 * R2 * C1 * C2)); // ~3090.533Hz

 	qfactor = pt2_sqrt(R1 * R2 * C1 * C2) / (C2 * (R1 + R2)); // ~0.660225

-	calcLEDFilterCoeffs(dPaulaOutputFreq, cutoff, qfactor, &filterLED);

+	setupTwoPoleFilter(dPaulaOutputFreq, cutoff, qfactor, &filterLED);

 void paulaDisableFilters(void) // disables low-pass/high-pass filter ("LED" filter is kept)

@@ -262,7 +261,7 @@

 			useLEDFilter = !!(data8 & 2);

 			if (useLEDFilter != oldLedFilterState)

-				clearLEDFilterState(&filterLED);

+				clearTwoPoleFilterState(&filterLED);

 		break;

@@ -441,13 +440,13 @@

 		double dOut[2] = { dOutL[i], dOutR[i] };

 		if (useLowpassFilter)

-			RCLowPassFilterStereo(&filterLo, dOut, dOut);

+			onePoleLPFilterStereo(&filterLo, dOut, dOut);

 		if (useLEDFilter)

-			LEDFilter(&filterLED, dOut, dOut);

+			twoPoleLPFilterStereo(&filterLED, dOut, dOut);

 		if (useHighpassFilter)

-			RCHighPassFilterStereo(&filterHi, dOut, dOut);

+			onePoleHPFilterStereo(&filterHi, dOut, dOut);

 		dOutL[i] = dOut[0];

 		dOutR[i] = dOut[1];

--- a/src/pt2_rcfilter.c

+++ /dev/null

@@ -1,58 +1,0 @@

-/* 1-pole 6dB/oct RC filters, from:

-** https://www.musicdsp.org/en/latest/Filters/116-one-pole-lp-and-hp.html

-**

-** There's no frequency pre-warping with tan(), but doing that would

-** result in a cutoff that sounded slightly too low.

-*/

-#include "pt2_math.h"

-#include "pt2_rcfilter.h"

-void calcRCFilterCoeffs(double sr, double hz, rcFilter_t *f)

-{

-	const double a = (hz < sr / 2.0) ? pt2_cos((PT2_TWO_PI * hz) / sr) : 1.0;

-	const double b = 2.0 - a;

-	const double c = b - pt2_sqrt((b * b) - 1.0);

-	f->c1 = 1.0 - c;

-	f->c2 = c;

-}

-void clearRCFilterState(rcFilter_t *f)

-{

-	f->tmp[0] = f->tmp[1] = 0.0;

-}

-void RCLowPassFilterStereo(rcFilter_t *f, const double *in, double *out)

-{

-	// left channel

-	f->tmp[0] = (f->c1 * in[0]) + (f->c2 * f->tmp[0]);

-	out[0] = f->tmp[0];

-	// right channel

-	f->tmp[1] = (f->c1 * in[1]) + (f->c2 * f->tmp[1]);

-	out[1] = f->tmp[1];

-}

-void RCHighPassFilterStereo(rcFilter_t *f, const double *in, double *out)

-{

-	// left channel

-	f->tmp[0] = (f->c1 * in[0]) + (f->c2 * f->tmp[0]);

-	out[0] = in[0] - f->tmp[0];

-	// right channel

-	f->tmp[1] = (f->c1 * in[1]) + (f->c2 * f->tmp[1]);

-	out[1] = in[1] - f->tmp[1];

-}

-void RCLowPassFilter(rcFilter_t *f, const double in, double *out)

-{

-	f->tmp[0] = (f->c1 * in) + (f->c2 * f->tmp[0]);

-	*out = f->tmp[0];

-}

-void RCHighPassFilter(rcFilter_t *f, const double in, double *out)

-{

-	f->tmp[0] = (f->c1 * in) + (f->c2 * f->tmp[0]);

-	*out = in - f->tmp[0];

-}

--- a/src/pt2_rcfilter.h

+++ /dev/null

@@ -1,16 +1,0 @@

-#pragma once

-#include <stdint.h>

-#include <stdbool.h>

-typedef struct rcFilter_t

-{

-	double tmp[2], c1, c2;

-} rcFilter_t;

-void calcRCFilterCoeffs(double sr, double hz, rcFilter_t *f);

-void clearRCFilterState(rcFilter_t *f);

-void RCLowPassFilterStereo(rcFilter_t *f, const double *in, double *out);

-void RCHighPassFilterStereo(rcFilter_t *f, const double *in, double *out);

-void RCLowPassFilter(rcFilter_t *f, const double in, double *out);

-void RCHighPassFilter(rcFilter_t *f, const double in, double *out);

--- /dev/null

+++ b/src/pt2_rcfilters.c

@@ -1,0 +1,122 @@

+#include "pt2_math.h"

+#include "pt2_rcfilters.h"

+#define SMALL_NUMBER (1E-4)

+/* 1-pole RC low-pass/high-pass filter, based on:

+** https://www.musicdsp.org/en/latest/Filters/116-one-pole-lp-and-hp.html

+*/

+void setupOnePoleFilter(double audioRate, double cutOff, onePoleFilter_t *f)

+{

+	if (cutOff >= audioRate/2.0)

+		cutOff = (audioRate/2.0) - SMALL_NUMBER;

+	const double a = 2.0 - pt2_cos((PT2_TWO_PI * cutOff) / audioRate);

+	const double b = a - pt2_sqrt((a * a) - 1.0);

+	f->a1 = 1.0 - b;

+	f->a2 = b;

+}

+void clearOnePoleFilterState(onePoleFilter_t *f)

+{

+	f->tmpL = f->tmpR = 0.0;

+}

+void onePoleLPFilter(onePoleFilter_t *f, const double in, double *out)

+{

+	f->tmpL = (f->a1 * in) + (f->a2 * f->tmpL);

+	*out = f->tmpL;

+}

+void onePoleLPFilterStereo(onePoleFilter_t *f, const double *in, double *out)

+{

+	// left channel

+	f->tmpL = (f->a1 * in[0]) + (f->a2 * f->tmpL);

+	out[0] = f->tmpL;

+	// right channel

+	f->tmpR = (f->a1 * in[1]) + (f->a2 * f->tmpR);

+	out[1] = f->tmpR;

+}

+void onePoleHPFilter(onePoleFilter_t *f, const double in, double *out)

+{

+	f->tmpL = (f->a1 * in) + (f->a2 * f->tmpL);

+	*out = in - f->tmpL;

+}

+void onePoleHPFilterStereo(onePoleFilter_t *f, const double *in, double *out)

+{

+	// left channel

+	f->tmpL = (f->a1 * in[0]) + (f->a2 * f->tmpL);

+	out[0] = in[0] - f->tmpL;

+	// right channel

+	f->tmpR = (f->a1 * in[1]) + (f->a2 * f->tmpR);

+	out[1] = in[1] - f->tmpR;

+}

+/* 2-pole RC low-pass filter with Q factor, based on:

+** https://www.musicdsp.org/en/latest/Filters/38-lp-and-hp-filter.html

+*/

+void clearTwoPoleFilterState(twoPoleFilter_t *f)

+{

+	f->tmpL[0] = f->tmpL[1] = f->tmpL[2] = f->tmpL[3] = 0.0;

+	f->tmpR[0] = f->tmpR[1] = f->tmpR[2] = f->tmpR[3] = 0.0;

+}

+void setupTwoPoleFilter(double audioRate, double cutOff, double qFactor, twoPoleFilter_t *f)

+{

+	if (cutOff >= audioRate/2.0)

+		cutOff = (audioRate/2.0) - SMALL_NUMBER;

+	const double a = 1.0 / pt2_tan((PT2_PI * cutOff) / audioRate);

+	const double b = 1.0 / qFactor;

+	f->a1 = 1.0 / (1.0 + b * a + a * a);

+	f->a2 = 2.0 * f->a1;

+	f->b1 = 2.0 * (1.0 - a*a) * f->a1;

+	f->b2 = (1.0 - b * a + a * a) * f->a1;

+}

+void twoPoleLPFilter(twoPoleFilter_t *f, const double in, double *out)

+{

+	const double LOut = (f->a1 * in) + (f->a2 * f->tmpL[0]) + (f->a1 * f->tmpL[1]) - (f->b1 * f->tmpL[2]) - (f->b2 * f->tmpL[3]);

+	// shift states

+	f->tmpL[1] = f->tmpL[0];

+	f->tmpL[0] = in;

+	f->tmpL[3] = f->tmpL[2];

+	f->tmpL[2] = LOut;

+	// set output

+	*out = LOut;

+}

+void twoPoleLPFilterStereo(twoPoleFilter_t *f, const double *in, double *out)

+{

+	const double LOut = (f->a1 * in[0]) + (f->a2 * f->tmpL[0]) + (f->a1 * f->tmpL[1]) - (f->b1 * f->tmpL[2]) - (f->b2 * f->tmpL[3]);

+	const double ROut = (f->a1 * in[1]) + (f->a2 * f->tmpR[0]) + (f->a1 * f->tmpR[1]) - (f->b1 * f->tmpR[2]) - (f->b2 * f->tmpR[3]);

+	// shift states

+	f->tmpL[1] = f->tmpL[0];

+	f->tmpL[0] = in[0];

+	f->tmpL[3] = f->tmpL[2];

+	f->tmpL[2] = LOut;

+	f->tmpR[1] = f->tmpR[0];

+	f->tmpR[0] = in[1];

+	f->tmpR[3] = f->tmpR[2];

+	f->tmpR[2] = ROut;

+	// set output

+	out[0] = LOut;

+	out[1] = ROut;

+}

--- /dev/null

+++ b/src/pt2_rcfilters.h

@@ -1,0 +1,26 @@

+#pragma once

+#include <stdint.h>

+#include <stdbool.h>

+typedef struct onePoleFilter_t

+{

+	double tmpL, tmpR, a1, a2;

+} onePoleFilter_t;

+typedef struct twoPoleFilter_t

+{

+	double tmpL[4], tmpR[4], a1, a2, b1, b2;

+} twoPoleFilter_t;

+void setupOnePoleFilter(double audioRate, double cutOff, onePoleFilter_t *f);

+void clearOnePoleFilterState(onePoleFilter_t *f);

+void onePoleLPFilterStereo(onePoleFilter_t *f, const double *in, double *out);

+void onePoleHPFilterStereo(onePoleFilter_t *f, const double *in, double *out);

+void onePoleLPFilter(onePoleFilter_t *f, const double in, double *out);

+void onePoleHPFilter(onePoleFilter_t *f, const double in, double *out);

+void setupTwoPoleFilter(double audioRate, double cutOff, double qFactor, twoPoleFilter_t *f);

+void clearTwoPoleFilterState(twoPoleFilter_t *f);

+void twoPoleLPFilter(twoPoleFilter_t *f, const double in, double *out);

+void twoPoleLPFilterStereo(twoPoleFilter_t *f, const double *in, double *out);

--- a/src/pt2_sampler.c

+++ b/src/pt2_sampler.c

@@ -16,7 +16,7 @@

 #include "pt2_sampler.h"

 #include "pt2_config.h"

 #include "pt2_bmp.h"

-#include "pt2_rcfilter.h"

+#include "pt2_rcfilters.h"

 #include "pt2_chordmaker.h"

 #include "pt2_replayer.h"

 #include "pt2_visuals_sync.h"

@@ -538,7 +538,7 @@

 void highPassSample(int32_t cutOff)

-	rcFilter_t filterHi;

+	onePoleFilter_t filterHi;

 	assert(editor.currSample >= 0 && editor.currSample <= 30);

@@ -599,9 +599,9 @@

 		editor.hpCutOff = (uint16_t)dCutOff;

-	calcRCFilterCoeffs(dBaseFreq, dCutOff, &filterHi);

+	setupOnePoleFilter(dBaseFreq, dCutOff, &filterHi);

-	clearRCFilterState(&filterHi);

+	clearOnePoleFilterState(&filterHi);

 	if (to <= s->length)

 		const int8_t *smpPtr = &song->sampleData[s->offset];

@@ -608,7 +608,7 @@

 		for (int32_t i = from; i < to; i++)

 			double dSmp = smpPtr[i];

-			RCHighPassFilter(&filterHi, dSmp, &dSampleData[i]);

+			onePoleHPFilter(&filterHi, dSmp, &dSampleData[i]);

@@ -637,7 +637,7 @@

 void lowPassSample(int32_t cutOff)

-	rcFilter_t filterLo;

+	onePoleFilter_t filterLo;

 	if (editor.sampleZero)

@@ -698,13 +698,13 @@

 		editor.lpCutOff = (uint16_t)dCutOff;

-	calcRCFilterCoeffs(dBaseFreq, dCutOff, &filterLo);

+	setupOnePoleFilter(dBaseFreq, dCutOff, &filterLo);

 	// copy over sample data to double buffer

 	for (int32_t i = 0; i < s->length; i++)

 		dSampleData[i] = song->sampleData[s->offset+i];

-	clearRCFilterState(&filterLo);

+	clearOnePoleFilterState(&filterLo);

 	if (to <= s->length)

 		const int8_t *smpPtr = &song->sampleData[s->offset];

@@ -711,7 +711,7 @@

 		for (int32_t i = from; i < to; i++)

 			double dSmp = smpPtr[i];

-			RCLowPassFilter(&filterLo, dSmp, &dSampleData[i]);

+			onePoleLPFilter(&filterLo, dSmp, &dSampleData[i]);

--- a/vs2019_project/pt2-clone/pt2-clone.vcxproj

+++ b/vs2019_project/pt2-clone/pt2-clone.vcxproj

@@ -249,7 +249,6 @@

     <ClInclude Include="..\..\src\pt2_helpers.h" />

     <ClInclude Include="..\..\src\pt2_hpc.h" />

     <ClInclude Include="..\..\src\pt2_keyboard.h" />

-    <ClInclude Include="..\..\src\pt2_ledfilter.h" />

     <ClInclude Include="..\..\src\pt2_math.h" />

     <ClInclude Include="..\..\src\pt2_mod2wav.h" />

     <ClInclude Include="..\..\src\pt2_module_loader.h" />

@@ -259,7 +258,7 @@

     <ClInclude Include="..\..\src\pt2_pat2smp.h" />

     <ClInclude Include="..\..\src\pt2_pattern_viewer.h" />

     <ClInclude Include="..\..\src\pt2_paula.h" />

-    <ClInclude Include="..\..\src\pt2_rcfilter.h" />

+    <ClInclude Include="..\..\src\pt2_rcfilters.h" />

     <ClInclude Include="..\..\src\pt2_downsample2x.h" />

     <ClInclude Include="..\..\src\pt2_replayer.h" />

     <ClInclude Include="..\..\src\pt2_sample_loader.h" />

@@ -301,13 +300,12 @@

     <ClCompile Include="..\..\src\pt2_helpers.c" />

     <ClCompile Include="..\..\src\pt2_hpc.c" />

     <ClCompile Include="..\..\src\pt2_keyboard.c" />

-    <ClCompile Include="..\..\src\pt2_ledfilter.c" />

     <ClCompile Include="..\..\src\pt2_main.c" />

     <ClCompile Include="..\..\src\pt2_math.c" />

     <ClCompile Include="..\..\src\pt2_mod2wav.c" />

     <ClCompile Include="..\..\src\pt2_module_loader.c" />

     <ClCompile Include="..\..\src\pt2_paula.c" />

-    <ClCompile Include="..\..\src\pt2_rcfilter.c" />

+    <ClCompile Include="..\..\src\pt2_rcfilters.c" />

     <ClCompile Include="..\..\src\pt2_replayer.c" />

     <ClCompile Include="..\..\src\pt2_module_saver.c" />

     <ClCompile Include="..\..\src\pt2_mouse.c" />

--- a/vs2019_project/pt2-clone/pt2-clone.vcxproj.filters

+++ b/vs2019_project/pt2-clone/pt2-clone.vcxproj.filters

@@ -90,7 +90,7 @@

     <ClInclude Include="..\..\src\pt2_visuals_sync.h">

       <Filter>headers</Filter>

     </ClInclude>

-    <ClInclude Include="..\..\src\pt2_rcfilter.h">

+    <ClInclude Include="..\..\src\pt2_rcfilters.h">

       <Filter>headers</Filter>

     </ClInclude>

     <ClInclude Include="..\..\src\pt2_chordmaker.h">

@@ -117,9 +117,6 @@

     <ClInclude Include="..\..\src\pt2_paula.h">

       <Filter>headers</Filter>

     </ClInclude>

-    <ClInclude Include="..\..\src\pt2_ledfilter.h">

-      <Filter>headers</Filter>

-    </ClInclude>

   </ItemGroup>

   <ItemGroup>

     <ClCompile Include="..\..\src\pt2_audio.c" />

@@ -192,7 +189,7 @@

     <ClCompile Include="..\..\src\pt2_replayer.c" />

     <ClCompile Include="..\..\src\pt2_sampling.c" />

     <ClCompile Include="..\..\src\pt2_visuals_sync.c" />

-    <ClCompile Include="..\..\src\pt2_rcfilter.c" />

+    <ClCompile Include="..\..\src\pt2_rcfilters.c" />

     <ClCompile Include="..\..\src\pt2_chordmaker.c" />

     <ClCompile Include="..\..\src\pt2_downsample2x.c" />

     <ClCompile Include="..\..\src\pt2_math.c" />

@@ -200,7 +197,6 @@

     <ClCompile Include="..\..\src\pt2_xpk.c" />

     <ClCompile Include="..\..\src\pt2_askbox.c" />

     <ClCompile Include="..\..\src\pt2_paula.c" />

-    <ClCompile Include="..\..\src\pt2_ledfilter.c" />

   </ItemGroup>

   <ItemGroup>

     <ResourceCompile Include="..\..\src\pt2-clone.rc" />