117 lines
3.9 KiB
C
117 lines
3.9 KiB
C
#include "i2s.h"
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#include "i2s_max98357.pio.h"
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#include <hardware/dma.h>
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#include <hardware/sync.h>
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#include <string.h>
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#include <stdio.h>
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#define audiocore_pio pio1
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#define AUDIO_BUFS 3
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struct i2s_context {
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unsigned pio_program_offset;
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int pio_sm;
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int dma_ch;
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dma_channel_config dma_config;
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uint32_t dma_buf[AUDIO_BUFS][I2S_DMA_BUF_SIZE];
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int cur_playing;
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bool has_data[AUDIO_BUFS];
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bool playback_active;
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};
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static struct i2s_context i2s_context;
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#define OUT_PIN 8
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#define SIDESET_BASE 6
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static void dma_isr(void)
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{
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if (!dma_channel_get_irq1_status(i2s_context.dma_ch))
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return;
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dma_channel_acknowledge_irq1(i2s_context.dma_ch);
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const int next_buf = (i2s_context.cur_playing + 1) % AUDIO_BUFS;
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if (i2s_context.playback_active && i2s_context.has_data[next_buf]) {
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i2s_context.cur_playing = next_buf;
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i2s_context.has_data[next_buf] = false;
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} else {
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memset(i2s_context.dma_buf[i2s_context.cur_playing], 0, sizeof(uint32_t) * I2S_DMA_BUF_SIZE);
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if (i2s_context.playback_active)
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printf("x");
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}
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dma_channel_transfer_from_buffer_now(i2s_context.dma_ch, i2s_context.dma_buf[i2s_context.cur_playing], I2S_DMA_BUF_SIZE);
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}
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static void setup_dma_config(void)
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{
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i2s_context.dma_config = dma_channel_get_default_config(i2s_context.dma_ch);
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channel_config_set_dreq(&i2s_context.dma_config, pio_get_dreq(pio1, i2s_context.pio_sm, true));
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}
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uint32_t *i2s_next_buf(void)
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{
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const long flags = save_and_disable_interrupts();
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const int next_buf = (i2s_context.cur_playing + 1) % AUDIO_BUFS;
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uint32_t *ret = NULL;
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if (!i2s_context.has_data[next_buf]) {
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ret = i2s_context.dma_buf[next_buf];
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} else {
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const int next_buf_2 = (next_buf + 1) % AUDIO_BUFS;
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if (!i2s_context.has_data[next_buf_2]) {
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ret = i2s_context.dma_buf[next_buf_2];
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}
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}
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restore_interrupts(flags);
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return ret;
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}
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void i2s_commit_buf(uint32_t *buf)
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{
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const long flags = save_and_disable_interrupts();
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const int next_buf = (i2s_context.cur_playing + 1) % AUDIO_BUFS;
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const int next_buf_2 = (next_buf + 1) % AUDIO_BUFS;
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if (i2s_context.dma_buf[next_buf] == buf) {
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i2s_context.has_data[next_buf] = true;
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} else if (i2s_context.dma_buf[next_buf_2] == buf) {
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i2s_context.has_data[next_buf_2] = true;
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i2s_context.playback_active = true;
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} else {
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assert(false);
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}
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restore_interrupts(flags);
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}
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bool i2s_init(int samplerate)
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{
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memset(i2s_context.dma_buf, 0, sizeof(i2s_context.dma_buf[0][0]) * 2* I2S_DMA_BUF_SIZE);
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if (!pio_can_add_program(audiocore_pio, (const pio_program_t *)&i2s_max98357_program))
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return false;
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i2s_context.pio_sm = pio_claim_unused_sm(audiocore_pio, false);
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if (i2s_context.pio_sm == -1)
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return false;
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i2s_context.pio_program_offset = pio_add_program(audiocore_pio, (const pio_program_t *)&i2s_max98357_program);
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i2s_max98357_program_init(audiocore_pio, i2s_context.pio_sm, i2s_context.pio_program_offset, OUT_PIN, SIDESET_BASE,
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samplerate);
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i2s_context.dma_ch = dma_claim_unused_channel(false);
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if (i2s_context.dma_ch == -1)
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goto out_dma_claim;
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i2s_context.playback_active = false;
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setup_dma_config();
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irq_add_shared_handler(DMA_IRQ_1, &dma_isr, PICO_SHARED_IRQ_HANDLER_DEFAULT_ORDER_PRIORITY);
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dma_channel_set_irq1_enabled(i2s_context.dma_ch, true);
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irq_set_enabled(DMA_IRQ_1, true);
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dma_channel_configure(i2s_context.dma_ch, &i2s_context.dma_config, &audiocore_pio->txf[i2s_context.pio_sm],
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i2s_context.dma_buf, I2S_DMA_BUF_SIZE, true);
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pio_sm_set_enabled(audiocore_pio, i2s_context.pio_sm, true);
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return true;
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out_dma_claim:
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pio_remove_program(audiocore_pio, (const pio_program_t *)&i2s_max98357_program, i2s_context.pio_program_offset);
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pio_sm_unclaim(audiocore_pio, i2s_context.pio_sm);
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return false;
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}
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