Merge branch 'master' of ghostdub.de:gg-button

gg.c

@@ -1,3 +1,6 @@
+#include <avr/io.h>
+
+#include "mmc.h"
 
 void timer_init_mega16(void)
 {
@@ -49,3 +52,54 @@ void timer_init_tiny26(void)
 	
 	TIMSK = 1 << TOIE1;/* interrupt on overflow */
 }
+
+
+uint8_t length[4];/* remaining samples */
+uint8_t mmc_position[4];/* current reading position on mmc */
+
+uint8_t overflows = 1;/* remaining counter overflows until next sample */
+#define SAMPLE_BITS 11
+
+#define BUFFER_SIZE 92
+#define REFRESH_AMOUNT 64
+#define REFRESH_SIZE (BUFFER_SIZE - REFRESH_AMOUNT)
+uint8_t buffer[BUFFER_SIZE];/* buffer for mmc data */
+
+uint8_t pos = 0;/* current playing position */
+uint8_t refresh_buffer = 0;/* position to start buffer refreshing */
+
+timerinterrupt()
+{
+	//if(!(TIFR & (1 << TOV1))) {continue;}/* interrupt flag polling */
+	//TIFR |= (1 << TOV1);/* done by hardware */
+	
+	overflows--;
+	if(!overflows)
+	{
+		overflows = 1 << (SAMPLE_BITS - 8);
+		pos = (pos + 1) % BUFFER_SIZE;
+	}
+	
+	/* TODO: a-law decoding */
+	/* TODO: 11bit PWM emulation */
+	OCR1A = buffer[pos];/* play next sample */
+}
+
+
+
+void main(void)
+{
+	if(mmc_init() != 0) {/* mmc fail */;}
+	timer_init_tiny26();
+	sei();
+	
+	for(;;)
+	{
+		if(pos == refresh_buffer)/* refresh buffer if running low */
+		{
+			mmc_read(mmc_position, buffer + (ref + REFRESH_SIZE) % BUFFER_SIZE, BUFFER_SIZE - ref, buffer, REFRESH_AMOUNT - (BUFFER_SIZE - ref));
+			/*       pos on sd   , first buffer address                       , 1st buffer size  ,2nd buf, 2nd buffer size                    */
+			refresh_buffer = (refresh_buffer + REFRESH_AMOUNT) % BUFFER_SIZE;
+		}
+	}
+}