main.c

#include "stdio.h"
#include "ezdsp5535.h"
#include "ezdsp5535_i2s.h"
#include "ezdsp5535_sar.h"
#include "board_setup.h"

#include "fraction.h"
#include "menu.h"

#define SAMPLE_RATE_KHZ 48
#define MAXINT16 32767
#define IMPULSE_SIZE 32
/* Execute idle instruction */
asm(" idle");

extern void init_aic3204(void);
extern void close_aic3204(void);
extern void pllInit(void);

void systemInit(void);
void initBuffer(void);
void insertSample(Int16);
Int16 getSample(Int16);

void audioLoop(void);
Int16 applyImpulse(Int16*);
Int16 mixer(Int16 ogData, Int16 filterData);
Int16 overdrive(Int16);
Int16 tremolo(Int16, Int16, Int16);

Int16 winBuff[IMPULSE_SIZE];
Int16 curPos = 0;
Int16 bufferFull = 0;
Int16 running = 0;
Int16 tremoloFreq = 3;

/** generated using the sine_table.py script **/
Int16 tableSize = 64;
Int16 sineTable[64][2] = {
	{0, 1},
	{5, 51}, {8, 41}, {9, 31}, {31, 81},
	{33, 70}, {5, 9}, {59, 93}, {70, 99},
	{126, 163}, {74, 89}, {127, 144}, {85, 92},
	{111, 116}, {51, 52}, {179, 180}, {1, 1},
	{179, 180}, {51, 52}, {111, 116}, {85, 92},
	{127, 144}, {74, 89}, {126, 163}, {70, 99},
	{59, 93}, {5, 9}, {33, 70}, {31, 81},
	{9, 31}, {8, 41}, {5, 51}, {0, 1},
	{-5, 51}, {-8, 41}, {-9, 31}, {-31, 81},
	{-33, 70}, {-5, 9}, {-59, 93}, {-70, 99},
	{-126, 163}, {-74, 89}, {-127, 144}, {-85, 92},
	{-111, 116}, {-51, 52}, {-179, 180}, {-1, 1},
	{-179, 180}, {-51, 52}, {-111, 116}, {-85, 92},
	{-127, 144}, {-74, 89}, {-126, 163}, {-70, 99},
	{-59, 93}, {-5, 9}, {-33, 70}, {-31, 81},
	{-9, 31}, {-8, 41}, {-5, 51},
};

Int16 lowPassImpulse[IMPULSE_SIZE][2] = {
	{1, 32}, {1, 32}, {1, 32}, {1, 32},
	{1, 32}, {1, 32}, {1, 32}, {1, 32},
	{1, 32}, {1, 32}, {1, 32}, {1, 32},
	{1, 32}, {1, 32}, {1, 32}, {1, 32},
	{1, 32}, {1, 32}, {1, 32}, {1, 32},
	{1, 32}, {1, 32}, {1, 32}, {1, 32},
	{1, 32}, {1, 32}, {1, 32}, {1, 32},
	{1, 32}, {1, 32}, {1, 32}, {1, 32}
};

Fraction ogMix;
Fraction filterMix;

void main()
{

	pllInit();
	// Initialize chip.
    EZDSP5535_init( );
	initMenu();
	
    // Initialize AIC3204 codec.
    init_aic3204();
    
    // Init the mixer default (0.5)
   	ogMix.n = 1;
	ogMix.d = 2;
	
    // Begin run.
    running = 1;
    // Begin audio loop. 
    audioLoop();
}


void insertData(Int16 data) 
{
	// If the buffer has still not been filled.
	if (!bufferFull) {
		// Add the sample to the buffer
		winBuff[curPos] = data;
		// Increment the cursor.
		curPos += 1;
		// If the cursor reaches the end
		if (curPos == IMPULSE_SIZE) {
			// Start cursor over, mark buffer as full.
			curPos = 0;
			bufferFull = 1;
		}
	}
	else {
		winBuff[curPos] = data;
		curPos = (curPos + 1) % IMPULSE_SIZE;
	}
}

Int16 getSample(Int16 index) {
	return winBuff[(curPos+index) % IMPULSE_SIZE];
}

void audioLoop() 
{
	Int16 sec=0, msec=0;
    Int16 sample, ogData, filterData;
    Int16 output;
    Int16 filterLevel = 0;
    
    while ( running ) {
    	for ( msec = 0; msec < 1000; msec++){
	        for ( sample = 0 ; sample < SAMPLE_RATE_KHZ ; sample++ )
	        {
	        	filterLevel = 0;
	        	// Only use left channel. 
	            EZDSP5535_I2S_readLeft(&ogData);
	            
	            // At first, filter data is equivalent. 
	            filterData = ogData;
	            output = 0;
	            // Insert the data into the windowing function.
	            insertData(ogData);
	            // Begin filter chain. If filterlevel is nonzero in menu, apply it. 
	            // Each consecutive filter is compounded on the previous. 
	            filterLevel = getFilterLevel(OPT_LOWPASS);
	            if (filterLevel != 0){
					filterData = applyImpulse((Int16*)lowPassImpulse);          
	            }
	            
				filterLevel = getFilterLevel(OPT_OVERDRIVE);
	            if (filterLevel != 0){
	            	filterData = overdrive(filterData);
	            }
	            
	            filterLevel = getFilterLevel(OPT_TREMOLO);
	            if (filterLevel != 0){
	            	// Tremolo has two modes: 3Hz and 8Hz
	            	tremoloFreq = filterLevel > 1 ? 8 : 3;
	            	filterData = tremolo(filterData, sec, msec);
	            }
	            // Apply mixing function.
	            //output = mixer(ogData, filterData);
	            output = filterData;
	            /* Write 16-bit right channel Data */
	            EZDSP5535_I2S_writeRight(output);
	            EZDSP5535_I2S_writeLeft(output);
	            
	        }
	        
	        // Check button events at 10Hz.
	        if (msec % 10 == 0) {
	        	// Update the button state.
				updateButtonState(EZDSP5535_SAR_getKey());
	        }
    	}
        sec++;
        if (sec*1000 < 0){
        	sec = 0;
        }
    }
    close_aic3204();
}

Int16 applyImpulse(Int16 *impResponse)
{
	Int16 i;
	Int16 index;
	Int16 windowData;
	Int16 sum = 0;
	for (i = 0; i < IMPULSE_SIZE; i++) {
		index = i*2;
		windowData = winBuff[i];
		sum += ndMultInt(impResponse[index], impResponse[index+1], windowData);
	}
	
	return sum;
}

Int16 mixer(Int16 ogData, Int16 filterData) 
{
	Int16 retVal = 0;
	
	filterMix = getUnitFraction(&ogMix);
	
	retVal += fMultInt(&ogMix, ogData);
	retVal += fMultInt(&filterMix, filterData);
	
	return retVal;
}

Int16 tremolo(Int16 data, Int16 sec, Int16 msec) 
{
	Int16 period = 1000/tremoloFreq;
	Int16 time = ((sec*1000) + msec) % period;
	Int16 phase = ndMultInt(tableSize, period, time);
	Int16 index = phase % tableSize;
	Int16 retVal;
	retVal = ndMultInt(sineTable[index][0], sineTable[index][1], data);
	return retVal;
}

Int16 overdrive(Int16 data) 
{
	if (abs(data) <= MAXINT16/3) {
		return data*4;
	}
	else if (abs(data) <= (MAXINT16/3) * 2) {
		return ndMultInt(4, 3, data);
	}
	else {
		return MAXINT16;
	}
}