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92 lines
1.9 KiB
92 lines
1.9 KiB
#include <avr/io.h>
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#include <util/delay.h>
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#include <avr/interrupt.h>
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#include "ringbuf_small.h"
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#include "ringbuf_small.c"
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#include "mmc.h"
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#include "gg.h"
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void timer_init_tiny26(void)
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{
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PLLCSR = 1 << PLLE;/* pll enable */
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_delay_us(100);
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while(!(PLLCSR & (1 << PLOCK))) {;}/* wait for lock */
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PLLCSR |= 1 << PCKE;/* use pll */
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OCR1C = 0xff;/* unused */
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/* output pin: OC1A = PB1 = 1 or OC1B = PB3 = 2 */
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OCR1A = 0;
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TCCR1A = (1 << COM1B1) | (1 << PWM1B);/* pwm enable, not inverted */
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TCCR1B = (1 << CS10);/* fast pwm, no prescaler */
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DDRB |= (1 << PB3);
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TIMSK = 1 << TOIE1;/* interrupt on overflow */
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}
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#define BUFFER_SIZE 32
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uint16_t buffer[BUFFER_SIZE];/* buffer for mmc data */
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ringbuf_t rb;
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uint32_t length;/* remaining samples */
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/*ISR(TIMER1_OVF1_vect, ISR_NAKED)
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{
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__asm__("in r2, 0x3f"); // save sreg
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if(--cnt_to_ocr_incr){
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OCR1A = cur_ocr + 1;
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}
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if(--cnt_to_next){
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cur_ocr = next_ocr;
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OCR1A = cur_ocr;
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cnt_to_ocr_incr = next_cnt_to_incr;
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cnt_to_next = 8;
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needs_new_data_flag = 1;
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}
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__asm__("out 0x3f,r2"); // restore sreg
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reti();
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}// */
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ISR(TIMER1_OVF1_vect){
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// next try: simplistic, not too much looking at speed
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uint16_t next;
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if(--cnt_to_next){
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ringbuf_get(&rb, &next);
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OCR1A = next>>8;
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cnt_to_ocr_incr = 7-(next & 0x7);
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cnt_to_next = 7;
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if(!--length)
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{
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/* shut down */
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PORTA &= ~(1 << PA7);
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}
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} else {
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if(--cnt_to_ocr_incr){
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OCR1A += 1;
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}
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}
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}
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int main(void) __attribute__((noreturn));
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int main(void)
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{
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DDRA |= (1 << PA7);
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PORTA |= (1 << PA7);
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ringbuf_init(&rb, buffer, BUFFER_SIZE);
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if(mmc_init() != 0) {/* mmc fail */;}
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mmc_read_part(0, (unsigned char *) &length, 4);
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timer_init_tiny26();
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sei();
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unsigned long block = 0;
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for(;; block++)
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{
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mmc_read_to_ringbuffer(block, &rb);
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}
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}
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