Change how inductor resets, fixes most popping when playing constant tones

src/audio/blip_buf.c

@@ -42,7 +42,7 @@ enum { time_bits = pre_shift + 20 };
 
 static fixed_t const time_unit = (fixed_t) 1 << time_bits;
 
-enum { bass_shift  = 9 }; /* affects high-pass filter breakpoint frequency */
+enum { bass_shift  = 2 }; /* affects high-pass filter breakpoint frequency */
 enum { end_frame_extra = 2 }; /* allows deltas slightly after frame length */
 
 enum { half_width  = 8 };

src/audio/inductor.c

@@ -9,40 +9,21 @@
 #define INDUCTOR_SPEAKER_RANGE 0x6000//prevent hitting the top or bottom of the speaker when switching direction rapidly
 
 
-float inductorCurrentCharge;
-float inductorChargeAtLastSample;
-
-
-void inductorReset(void){
-   inductorCurrentCharge = 0.0;
-   inductorChargeAtLastSample = 0.0;
-}
-
 void inductorPwmDutyCycle(int32_t now, int32_t clocks, float dutyCycle){
    int32_t onClocks = clocks * dutyCycle;
    int32_t offClocks = clocks * (1.00 - dutyCycle);
+   float inductorCurrentCharge;
+   float inductorChargeAtLastSample;
 
 #if !defined(EMU_NO_SAFETY)
    if(now + clocks >= AUDIO_CLOCK_RATE)
       return;
 #endif
 
-   inductorCurrentCharge = fMin(inductorCurrentCharge + onClocks * INDUCTOR_CLOCK_POWER, 1.0);
-   blip_add_delta(palmAudioResampler, now, (inductorCurrentCharge - inductorChargeAtLastSample) * INDUCTOR_SPEAKER_RANGE);
+   inductorCurrentCharge = fMin(onClocks * INDUCTOR_CLOCK_POWER, 1.0);
+   blip_add_delta(palmAudioResampler, now, inductorCurrentCharge * INDUCTOR_SPEAKER_RANGE);
    inductorChargeAtLastSample = inductorCurrentCharge;
 
    inductorCurrentCharge = fMax(-1.0, inductorCurrentCharge - offClocks * INDUCTOR_CLOCK_POWER);
    blip_add_delta(palmAudioResampler, now + onClocks, (inductorCurrentCharge - inductorChargeAtLastSample) * INDUCTOR_SPEAKER_RANGE);
-   inductorChargeAtLastSample = inductorCurrentCharge;
-}
-
-void inductorPwmOff(int32_t now, int32_t clocks){
-   //drift towards 0
-   if(inductorCurrentCharge > 0.0)
-      inductorCurrentCharge = fMax(0.0, inductorCurrentCharge - clocks * INDUCTOR_CLOCK_POWER);
-   else
-      inductorCurrentCharge = fMin(inductorCurrentCharge + clocks * INDUCTOR_CLOCK_POWER, 0.0);
-
-   blip_add_delta(palmAudioResampler, now, (inductorCurrentCharge - inductorChargeAtLastSample) * INDUCTOR_SPEAKER_RANGE);
-   inductorChargeAtLastSample = inductorCurrentCharge;
 }

src/audio/inductor.h

@@ -3,12 +3,6 @@
 
 #include <stdint.h>
 
-extern float inductorCurrentCharge;
-extern float inductorChargeAtLastSample;
-
-void inductorReset(void);
-
 void inductorPwmDutyCycle(int32_t now, int32_t clocks, float dutyCycle);
-void inductorPwmOff(int32_t now, int32_t clocks);
 
 #endif

src/emulator.c

@@ -4,7 +4,6 @@
 #include <string.h>
 
 #include "audio/blip_buf.h"
-#include "audio/inductor.h"
 #include "flx68000.h"
 #include "emulator.h"
 #include "hardwareRegisters.h"
@@ -111,7 +110,6 @@ uint32_t emulatorInit(buffer_t palmRomDump, buffer_t palmBootDump, uint32_t spec
    sed1376Reset();
    ads7846Reset();
    pdiUsbD12Reset();
-   inductorReset();
    sandboxInit();
 
    memset(&palmInput, 0x00, sizeof(palmInput));
@@ -157,7 +155,6 @@ void emulatorHardReset(void){
    sed1376Reset();
    ads7846Reset();
    pdiUsbD12Reset();
-   inductorReset();
    setRtc(0, 0, 0, 0);
 }
 
@@ -203,7 +200,6 @@ uint64_t emulatorGetStateSize(void){
    size += sizeof(int32_t);//pwm1ClocksToNextSample
    size += sizeof(uint8_t) * 6;//pwm1Fifo[6]
    size += sizeof(uint8_t) * 2;//pwm1(Read/Write)
-   size += sizeof(uint64_t) * 2;//inductorCurrentCharge / inductorChargeAtLastSample
    size += sizeof(uint8_t) * 7;//palmMisc
    size += sizeof(uint32_t);//palmSdCard.command
    size += sizeof(uint8_t) * 2;//palmSdCard.response / palmSdCard.commandBitsRemaining
@@ -330,10 +326,6 @@ bool emulatorSaveState(buffer_t buffer){
    offset += sizeof(uint8_t);
    writeStateValue8(buffer.data + offset, pwm1WritePosition);
    offset += sizeof(uint8_t);
-   writeStateValueDouble(buffer.data + offset, inductorCurrentCharge);
-   offset += sizeof(uint64_t);
-   writeStateValueDouble(buffer.data + offset, inductorChargeAtLastSample);
-   offset += sizeof(uint64_t);
 
    //misc
    writeStateValueBool(buffer.data + offset, palmMisc.powerButtonLed);
@@ -487,10 +479,6 @@ bool emulatorLoadState(buffer_t buffer){
    offset += sizeof(uint8_t);
    pwm1WritePosition = readStateValue8(buffer.data + offset);
    offset += sizeof(uint8_t);
-   inductorCurrentCharge = readStateValueDouble(buffer.data + offset);
-   offset += sizeof(uint64_t);
-   inductorChargeAtLastSample = readStateValueDouble(buffer.data + offset);
-   offset += sizeof(uint64_t);
 
    //misc
    palmMisc.powerButtonLed = readStateValueBool(buffer.data + offset);

src/hardwareRegistersAccessors.c.h

@@ -621,8 +621,8 @@ static void samplePwm1(bool forClk32, double sysclks){
    int32_t audioNow;
    int32_t audioClocks;
 
-   //check if enabled and validate clock mode, CLK32 is used if PLL is disabled as the inductor still needs to settle
-   if(forClk32 != !!(pwmc1 & 0x8000) && !(forClk32 && palmSysclksPerClk32 < 1.0))
+   //check if enabled and validate clock mode
+   if(forClk32 != !!(pwmc1 & 0x8000))
       return;
 
    //these calculations are fairly heavy, only do them after we know the clock mode is valid
@@ -642,10 +642,6 @@ static void samplePwm1(bool forClk32, double sysclks){
          audioNow += audioUsed;
       }
    }
-   else{
-      //PWM1 not enabled
-      inductorPwmOff(audioNow, audioClocks);
-   }
 }
 
 static uint16_t getPwmc1(void){