AudioBufferManager(I2s, PWMAudio, ADCInput) clicking fix (earlephilhower#1500)

earlephilhower · web-flow · commit 3c408dab7c64 · 2023-06-04T18:40:29.000-07:00
The ABM had an off-by-one error in the DMA buffer swapover. Instead of setting the DMA address to the newly added buffer in active[], it set it to the buffer that was currently running. This would effectively disable the ping-pong and cause clicks/lost data. Fixes earlephilhower#1491
diff --git a/libraries/AudioBufferManager/src/AudioBufferManager.cpp b/libraries/AudioBufferManager/src/AudioBufferManager.cpp
@@ -257,7 +257,7 @@ void __not_in_flash_func(AudioBufferManager::_dmaIRQ)(int channel) {
             _active[1] = _takeFromList(&_filled);
         }
         _overunderflow = _overunderflow | (_active[1] == _silence);
-        dma_channel_set_read_addr(channel, _active[0]->buff, false);
+        dma_channel_set_read_addr(channel, _active[1]->buff, false);
     } else {
         if (_empty) {
             _addToList(&_filled, _active[0]);
@@ -266,7 +266,7 @@ void __not_in_flash_func(AudioBufferManager::_dmaIRQ)(int channel) {
         } else {
             _overunderflow = true;
         }
-        dma_channel_set_write_addr(channel, _active[0]->buff, false);
+        dma_channel_set_write_addr(channel, _active[1]->buff, false);
     }
     dma_channel_set_trans_count(channel, _wordsPerBuffer * (_dmaSize == DMA_SIZE_16 ? 2 : 1), false);
     dma_channel_acknowledge_irq0(channel);

Original file line number	Diff line number	Diff line change
`@@ -257,7 +257,7 @@ void __not_in_flash_func(AudioBufferManager::_dmaIRQ)(int channel) {`
`257`	`257`	`_active[1] = _takeFromList(&_filled);`
`258`	`258`	`}`
`259`	`259`	`_overunderflow = _overunderflow \| (_active[1] == _silence);`
`260`		`- dma_channel_set_read_addr(channel, _active[0]->buff, false);`
	`260`	`+ dma_channel_set_read_addr(channel, _active[1]->buff, false);`
`261`	`261`	`} else {`
`262`	`262`	`if (_empty) {`
`263`	`263`	`_addToList(&_filled, _active[0]);`
`@@ -266,7 +266,7 @@ void __not_in_flash_func(AudioBufferManager::_dmaIRQ)(int channel) {`
`266`	`266`	`} else {`
`267`	`267`	`_overunderflow = true;`
`268`	`268`	`}`
`269`		`- dma_channel_set_write_addr(channel, _active[0]->buff, false);`
	`269`	`+ dma_channel_set_write_addr(channel, _active[1]->buff, false);`
`270`	`270`	`}`
`271`	`271`	`dma_channel_set_trans_count(channel, _wordsPerBuffer * (_dmaSize == DMA_SIZE_16 ? 2 : 1), false);`
`272`	`272`	`dma_channel_acknowledge_irq0(channel);`