static VOID FillAudioBuffer(WAVESTREAM *wsPtr) {
ULONG space;
ULONG bytesWritten = 0; // just for tracePerf
STREAM *streamPtr = wsPtr->streamPtr;
AUDIOBUFFER *abPtr = &wsPtr->waPtr->ab;
// while have process buffers and there is space in the audio buffer, write data to the audio buffer
#ifdef TRACE_FILLAUDIOBUFFER
tracePerf(TRACE_FILLAUDIOBUFFER_IN, _IF());
#endif
space = abSpace(abPtr) & ALIGN_FILL_PLAY;
while(space && sbNotEmpty(&streamPtr->sbaProc)) {
bytesWritten = bytesWritten + WriteAudioBuffer(wsPtr); // bytesWritten just for tracePerf
space = abSpace(abPtr) & ALIGN_FILL_PLAY;
}
#ifdef TRACE_FILLAUDIOBUFFER
tracePerf(TRACE_FILLAUDIOBUFFER_OUT, (bytesWritten << 16) | _IF()); //
#endif
return;
}
void Phaser()
{
// Initialize hardware
InitAudio(44100);
InitDisplay_DOGM128();
InitEncoders();
// Calibrate touch screen
TwoPointCalibration cal;
TwoPointCalibrate_TSC2046(&cal);
// Prepare a cleared screen
static uint8_t screen[1024];
extern uint8_t background[1204];
memcpy(screen,background,sizeof(screen));
UpdateDisplay_DOGM128(screen);
// Set up effect parameters and buffers
const int midpoint=60; // The midpoint for the delay offset value
int mix=0x8000; // Mixing factor for the phaser effect - set to 50%
int feedback=0x8000; // Feedback factor for the phaser effect - set to 50%
int count=0; // LFO control counter
int maxcount=64; // The number of iterations to run before updating the LFO
bool update=true; // Update flag for the screen
static int32_t inbuf[NumberOfSamples*2],outbuf[NumberOfSamples*2]; // Input and output audio buffers
static int32_t tmpbuf1[NumberOfSamples],tmpbuf2[NumberOfSamples]; // Temporary audio buffers
// Initialize the phaser effects for both stereo channels
static DelayPhaser dp[2];
InitDelayPhaser(&dp[0],0,mix,feedback);
InitDelayPhaser(&dp[1],0,mix,feedback);
// Initialize an LFO to control the phaser effect
LFO lfo;
InitLFO(&lfo,80,20); // period of 80, amplitude of +-20
// This loop processes 16 stereo samples at a time,
// and thus run in 16/44100 seconds, or 363 microseconds.
for(;;)
{
// Read input from the audio codec
ReadFullAudioBuffer(inbuf,NumberOfSamples*2);
// Get input from the touch screen
int x,y;
bool press=CalibratedTouchscreenPosition_TSC2046(&cal,&x,&y);
if(press)
{
// Handle clicks on the delay slider
if(x>=18-9&&x<55-9)
{
int oldcount=maxcount;
maxcount=(63-y)*4;
if(oldcount!=maxcount) update=true;
}
// Handle clicks on the mixing slider
else if(x>=55-9&&x<92-9)
{
int oldmix=mix;
mix=(63-y)*0x400;
SetDelayPhaserMix(&dp[0],mix);
SetDelayPhaserMix(&dp[1],mix);
if(oldmix!=mix) update=true;
}
// Handle clicks on the feedback slider
else if(x>=92-9&&x<92+2*18)
{
int oldfeedback=feedback;
feedback=(63-y)*0x400;
SetDelayPhaserFeedback(&dp[0],feedback);
SetDelayPhaserFeedback(&dp[1],feedback);
if(oldfeedback!=feedback) update=true;
}
}
// Read input from the encoders
int rot0=ReadEncoderChange(0);
int rot1=ReadEncoderChange(1);
int rot2=ReadEncoderChange(2);
// Handle delay encoder
if(rot0)
{
maxcount+=4*rot0;
if(maxcount<0) maxcount=0;
update=true;
}
// Handle mixing encoder
if(rot1)
{
mix+=0x800*rot1;
if(mix>0x10000) mix=0x10000;
if(mix<0) mix=0;
SetDelayPhaserMix(&dp[0],mix);
SetDelayPhaserMix(&dp[1],mix);
update=true;
}
// Handle feedback encoder
if(rot2)
{
feedback+=0x800*rot2;
if(feedback>0x10000) feedback=0x10000;
if(feedback<0) feedback=0;
SetDelayPhaserFeedback(&dp[0],feedback);
SetDelayPhaserFeedback(&dp[1],feedback);
update=true;
}
// Update screen if necessary
// TODO: fix this code snippet since it takes too much time to execute and therefore distorts the audio signal
if(update)
{
// Draw delay slider
int delayheight=maxcount/4;
EraseFilledRectangle(screen,18,0,18,64-delayheight);
DrawFilledRectangle(screen,18,64-delayheight,18,delayheight);
// Draw mixing slider
int mixheight=mix/0x400;
EraseFilledRectangle(screen,55,0,18,64-mixheight);
DrawFilledRectangle(screen,55,64-mixheight,18,mixheight);
// Draw feedback slider
int feedbackheight=feedback/0x400;
EraseFilledRectangle(screen,92,0,18,64-feedbackheight);
DrawFilledRectangle(screen,92,64-feedbackheight,18,feedbackheight);
//UpdateDisplay_DOGM128(screen);
j=0;
update=false;
screenupdated=true;
}
if(screenupdated) {
if (my_updatedisplay(screen) == 8) {
screenupdated=false;
}
}
// Run LFO if needed
if(++count>=maxcount)
{
count=0;
int lfoval=RunTriangleLFO(&lfo);
SetDelayPhaserOffset(&dp[0],lfoval+midpoint);
SetDelayPhaserOffset(&dp[1],lfoval+midpoint);
}
// Run phaser effect
for(int channel=0;channel<2;channel++)
{
// Extract one channel from the input to a temporary buffer
for(int i=0;i<NumberOfSamples;i++) tmpbuf1[i]=inbuf[2*i+channel];
// Run effect in temporary buffers
RunDelayPhaser(&dp[channel],tmpbuf1,tmpbuf2,NumberOfSamples);
// Write processed samples back to the output buffer
for(int i=0;i<NumberOfSamples;i++) outbuf[2*i+channel]=tmpbuf2[i];
}
// Send output buffer to audio codec
WriteAudioBuffer(outbuf,NumberOfSamples*2);
}
}
