90 lines
2.5 KiB
C
90 lines
2.5 KiB
C
/** @file dma_cbuf.c
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* Module handling Direct Memory Access controller's circular system
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*
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* The module provides a convenient tool to receive data from a peripheral in a
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* buffered, low-latency, low-cpu usage, non-blocking way
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*/
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//--includes--------------------------------------------------------------------
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#include "dma_cbuf.h"
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//--local definitions-----------------------------------------------------------
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#define DMA_CONFIG (DMA_CONFIG_IRQ_COMPLETE | DMA_CONFIG_FROM_PERIPH \
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| DMA_CONFIG_CIRCULAR | DMA_CONFIG_INC_MEM \
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| DMA_CONFIG_PSIZE_8BITS | DMA_CONFIG_MSIZE_8BITS)
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static void cbuf_callback(enum DmaIRQSource src, volatile void* param);
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//--local variables-------------------------------------------------------------
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//--public functions------------------------------------------------------------
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void dma_cbuf_configure(volatile struct DmaCircBuffer* buffer,
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volatile void* raw_buffer, volatile void* src, uint16_t buffer_size,
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enum DmaPeriph dma, enum DmaChannel channel, enum DmaConfig priority)
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{
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#warning "check for null ptr"
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buffer->buffer = raw_buffer;
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buffer->src = src;
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buffer->size = buffer_size;
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buffer->begin = 0;
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buffer->dma = dma;
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buffer->channel = channel;
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buffer->config = DMA_CONFIG | priority;
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buffer->dma_looped = false;
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dma_configure(buffer->dma, buffer->channel, buffer->config, buffer->src,
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buffer->buffer, buffer->size, cbuf_callback, buffer);
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}
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uint32_t dma_cbuf_read_byte(volatile struct DmaCircBuffer* buffer,
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uint8_t* byte)
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{
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//retreive the current end of the buffer based on the DMA's progress
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uint16_t end = buffer->size
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- dma_get_remaining(buffer->dma, buffer->channel);
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//check for bytes to read and overflow
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if ((end > buffer->begin) && buffer->dma_looped) {
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//TODO overflow
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buffer->begin = end;
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} else if ((buffer->begin == end) && !buffer->dma_looped) {
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//TODO no data
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return 1;
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}
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//read the oldest byte and advance the buffer
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uint8_t* raw_buffer = (uint8_t*)buffer->buffer;
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*byte = raw_buffer[buffer->begin];
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++buffer->begin;
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if (buffer->begin >= buffer->size) {
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buffer->begin = 0;
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buffer->dma_looped = false;
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}
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return 0;
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}
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//--local functions-------------------------------------------------------------
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/**
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* Callback called on DMA RX tranfert's completion. Sets a flag needed to
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* properly handle the circular buffer
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*/
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static void cbuf_callback(enum DmaIRQSource src, volatile void* param)
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{
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(void)src; //only transfer complete expected
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volatile struct DmaCircBuffer* buffer = param;
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buffer->dma_looped = true;
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}
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