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tuneSample() fix for Amiga periods

--- a/src/ft2_replayer.c

+++ b/src/ft2_replayer.c

@@ -130,7 +130,9 @@

 	#define MIN_PERIOD (0)

 	#define MAX_PERIOD (((10*12*16)-1)-1) /* -1 (because of bugged amigaPeriods table values) */

+	double (*dGetHzFromPeriod)(int32_t) = linearPeriodsFlag ? &linearPeriod2Hz : &amigaPeriod2Hz;

 	const uint16_t *periodTab = linearPeriodsFlag ? linearPeriods : amigaPeriods;

+

 	if (midCFreq <= 0 || periodTab == NULL)

 	{

 		s->fine = s->relTon = 0;

@@ -139,7 +141,7 @@

 	// handle frequency boundaries first...

-	if (midCFreq <= (int32_t)dPeriod2HzTab[periodTab[MIN_PERIOD]])

+	if (midCFreq <= (int32_t)dGetHzFromPeriod(periodTab[MIN_PERIOD]))

 	{

 		s->fine = -128;

 		s->relTon = -48;

@@ -146,7 +148,7 @@

 		return;

 	}

-	if (midCFreq >= (int32_t)dPeriod2HzTab[periodTab[MAX_PERIOD]])

+	if (midCFreq >= (int32_t)dGetHzFromPeriod(periodTab[MAX_PERIOD]))

 	{

 		s->fine = 127;

 		s->relTon = 71;

@@ -154,9 +156,10 @@

 	}

 	// check if midCFreq is matching any of the non-finetuned note frequencies (C-0..B-9)

+

 	for (int8_t i = 0; i < 10*12; i++)

 	{

-		if (midCFreq == (int32_t)dPeriod2HzTab[periodTab[16 + (i<<4)]])

+		if (midCFreq == (int32_t)dGetHzFromPeriod(periodTab[16 + (i<<4)]))

 		{

 			s->fine = 0;

 			s->relTon = i - NOTE_C4;

@@ -169,13 +172,13 @@

 	int32_t period = MAX_PERIOD;

 	for (; period >= MIN_PERIOD; period--)

 	{

-		const int32_t curr = (int32_t)dPeriod2HzTab[periodTab[period]];

+		const int32_t curr = (int32_t)dGetHzFromPeriod(periodTab[period]);

 		if (midCFreq == curr)

 			break;

 		if (midCFreq > curr)

 		{

-			const int32_t next = (int32_t)dPeriod2HzTab[periodTab[period+1]];

+			const int32_t next = (int32_t)dGetHzFromPeriod(periodTab[period+1]);

 			const int32_t errorCurr = ABS(curr-midCFreq);

 			const int32_t errorNext = ABS(next-midCFreq);

@@ -257,27 +260,39 @@

 	return i+1;

 }

-static void calcPeriod2HzTable(void) // called every time "linear/amiga frequency" mode is changed

+double linearPeriod2Hz(int32_t period)

 {

-	dPeriod2HzTab[0] = 0.0; // in FT2, a period of 0 converts to 0Hz

+	if (period == 0)

+		return 0.0; // in FT2, a period of 0 gives 0Hz

+	const uint16_t invPeriod = (uint16_t)(12 * 192 * 4) - (uint16_t)period; // this intentionally 16-bit-underflows to be accurate to FT2

+	const int32_t quotient = invPeriod / 768;

+	const int32_t remainder = invPeriod % 768;

+

+	return dLogTab[remainder] * dExp2MulTab[(14-quotient) & 31]; // x = y >> ((14-octave) & 31)

+}

+

+double amigaPeriod2Hz(int32_t period)

+{

+	if (period == 0)

+		return 0.0; // in FT2, a period of 0 gives 0Hz

+

+	return (double)(8363*1712) / period;

+}

+

+static void calcPeriod2HzTable(void) // called every time "linear/amiga frequency" mode is changed

+{

 	if (audio.linearPeriodsFlag)

 	{

 		// linear periods

-		for (int32_t i = 1; i < 65536; i++)

-		{

-			const uint16_t invPeriod = (12 * 192 * 4) - (uint16_t)i; // this intentionally 16-bit-underflows to be accurate to FT2

-			const int32_t octave = invPeriod / 768;

-			const int32_t period = invPeriod % 768;

-

-			dPeriod2HzTab[i] = dLogTab[period] * dExp2MulTab[(14-octave) & 31]; // x = y >> ((14-octave) & 31)

-		}

+		for (int32_t i = 0; i < 65536; i++)

+			dPeriod2HzTab[i] = linearPeriod2Hz(i);

 	}

 	else

 	{

 		// Amiga periods

-		for (int32_t i = 1; i < 65536; i++)

-			dPeriod2HzTab[i] = (8363.0 * 1712.0) / i;

+		for (int32_t i = 0; i < 65536; i++)

+			dPeriod2HzTab[i] = amigaPeriod2Hz(i);

 	}

 }

@@ -466,7 +481,7 @@

 	}

 }

-double dPeriod2Hz(uint16_t period)

+double dPeriod2Hz(uint16_t period) // uses LUT for fast operation

 {

 	return dPeriod2HzTab[period];

 }

--- a/src/ft2_replayer.h

+++ b/src/ft2_replayer.h

@@ -265,7 +265,11 @@

 void calcRevMixDeltaTable(void);

 void calcReplayerLogTab(void);

-double dPeriod2Hz(uint16_t period);

+

+double linearPeriod2Hz(int32_t period);

+double amigaPeriod2Hz(int32_t period);

+

+double dPeriod2Hz(uint16_t period); // uses LUT for fast operation

 int64_t getMixerDelta(uint16_t period);

 uint32_t getRevMixerDelta(uint16_t period);