reduce time in mutex lock

Author: sctanf

i2s/audio_i2s.c

@@ -53,10 +53,10 @@ bufring2=bufring1;
 cpu_freq = freq;
 }
 
-uint32_t buflends[8192];
 void audioi2sconstuff2() {
     uint32_t divider = (cpu_freq * 2 / 48000) - ((bufring2->len - 16)/2);
     buflends[bufring2->index1] = divider;
+//    buflends[bufring2->index1] = divider;
     pio_sm_set_clkdiv_int_frac(audio_pio, shared_state.pio_sm, divider >> 8u, divider & 0xffu);
 }
 
@@ -149,7 +149,10 @@ static void update_pio_frequency(uint32_t sample_freq) {
 }
 
 static inline void audio_start_dma_transfer() {
-while (bufring2->corelock == 1) {tight_loop_contents();}
+    dma_channel_config c = dma_get_channel_config(shared_state.dma_channel);
+    channel_config_set_read_increment(&c, true);
+    dma_channel_set_config(shared_state.dma_channel, &c, false);
+//while (bufring2->corelock == 1) {tight_loop_contents();}
 mutex_enter_blocking(&bufring2->corelock2);
 //bufring2->corelock = 2;
     if (bufring2->len < 2) {
@@ -164,17 +167,13 @@ irq_set_enabled(DMA_IRQ_0 + PICO_AUDIO_I2S_DMA_IRQ, true);
 pio_sm_set_enabled(audio_pio, shared_state.pio_sm, true);
 */
         static uint32_t zero;
-        dma_channel_config c = dma_get_channel_config(shared_state.dma_channel);
         channel_config_set_read_increment(&c, false);
         dma_channel_set_config(shared_state.dma_channel, &c, false);
         dma_channel_transfer_from_buffer_now(shared_state.dma_channel, &zero, 2);
         return;
     }
-    dma_channel_config c = dma_get_channel_config(shared_state.dma_channel);
-    channel_config_set_read_increment(&c, true);
-    dma_channel_set_config(shared_state.dma_channel, &c, false);
     dma_channel_transfer_from_buffer_now(shared_state.dma_channel, bufring2->buf+bufring2->index1, 2);
-    buflends[bufring2->index1+1] = bufring2->len;
+//    buflends[bufring2->index1+1] = bufring2->len;
     bufring2->len = bufring2->len - 2;
     bufring2->index1 = (bufring2->index1 + 2) % (1024-32);
 //bufring2->corelock = 0;
@@ -191,7 +190,7 @@ mutex_enter_blocking(&bufring4->corelock2);
     channel_config_set_write_increment(&c, true);
     dma_channel_set_config(shared_state2.dma_channel, &c, false);
     dma_channel_transfer_to_buffer_now(shared_state2.dma_channel, bufring4->buf+bufring4->index1, 2);
-    buflends[bufring4->index1+1] = bufring4->len;
+//    buflends[bufring4->index1+1] = bufring4->len;
     bufring4->len = bufring4->len + 2;
     bufring4->index = (bufring4->index + 2) % (1024-32);
 //bufring4->corelock = 0;

i2s/include/pico/audio_i2s.h

@@ -112,7 +112,7 @@ int32_t buf[1024];
 int len;
 int index;
 int index1;
-int corelock;
+//int corelock;
 mutex_t corelock2;
 } bufring_t;
 void audioi2sconstuff(bufring_t *bufring1, uint32_t freq);

main.c

@@ -802,17 +802,18 @@ static void __not_in_flash_func(_as_audio_packet)(struct usb_endpoint *ep) { //
     }
 #endif
 
+    for (int i = 0; i < count * 2; i++)
+        buf0[i] = buf0[i] << HEADROOM;
 //    while (bufring1.len > 1024-32-2-(count * 2)) {tight_loop_contents();}
 mutex_enter_blocking(&bufring1.corelock2);
 //while (bufring1.corelock == 2) {tight_loop_contents();}
 //bufring1.corelock = 1; // 20us
     audioi2sconstuff2();
     int curin = bufring1.index;
     for (int i = 0; i < count * 2; i++) {
-        bufring1.buf[curin] = buf0[i] << HEADROOM;
-        if (curin < 32) {
+        bufring1.buf[curin] = buf0[i];
+        if (curin < 32)
             bufring1.buf[curin+1024-32] = bufring1.buf[curin];
-        }
         curin++;
         curin %= 1024-32;
     }