108 lines
2.7 KiB
C
108 lines
2.7 KiB
C
/** @file dma_mbuf.h
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* Module handling Direct Memory Access controller's multibuffer system
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*
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* The module provides a convenient tool to send data to a peripheral in a
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* buffered, low-altency, low-cpu usage, non-blocking way
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*/
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//--includes--------------------------------------------------------------------
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#include "dma_mbuf.h"
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//--local definitions-----------------------------------------------------------
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/**
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* DMA configuration to be used for the buffer. Additionnal configuration may be
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* added by the peripherals used
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*/
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#define DMA_CONFIG (DMA_CONFIG_IRQ_COMPLETE | DMA_CONFIG_FROM_MEM \
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| DMA_CONFIG_INC_MEM | DMA_CONFIG_MSIZE_8BITS)
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static void mbuf_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_mbuf_configure(volatile struct DmaMultiBuffer* buffer,
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const struct DmaParam* param, enum DmaConfig priority,
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void* raw_buffer, uint16_t buffer_size)
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{
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#warning "check for null ptr"
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buffer->raw_buffer = raw_buffer;
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buffer->buffer_size = buffer_size / 2;
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buffer->byte_index = 0;
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buffer->buffer_index = 0;
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buffer->dma = param->dma;
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buffer->channel = param->channel;
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buffer->dma_running = false;
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dma_configure(buffer->dma, buffer->channel,
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DMA_CONFIG | param->config | priority,
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param->periph, mbuf_callback, buffer);
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}
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uint32_t dma_mbuf_write_byte(volatile struct DmaMultiBuffer* buffer,
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uint8_t byte)
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{
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//if the current buffer is full, give up
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if (buffer->byte_index >= buffer->buffer_size) {
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return 1;
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}
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//write the byte
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buffer->raw_buffer[buffer->buffer_index * buffer->buffer_size
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+ buffer->byte_index] = byte;
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++buffer->byte_index;
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return 0;
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}
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uint32_t dma_mbuf_switch(volatile struct DmaMultiBuffer* buffer)
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{
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//no data to send, stop here
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if (buffer->byte_index == 0) {
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return 0;
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}
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//dma already running, give up
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if (buffer->dma_running) {
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return 1;
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}
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//start a new transfer
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buffer->dma_running = true;
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dma_start(buffer->dma, buffer->channel,
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&buffer->raw_buffer[buffer->buffer_index * buffer->buffer_size],
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buffer->byte_index);
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buffer->byte_index = 0;
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++buffer->buffer_index;
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if (buffer->buffer_index > 1) {
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buffer->buffer_index = 0;
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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 TX tranfert's completion. Stops the DMA and notifies
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* the buffer that the transfer is done.
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*/
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static void mbuf_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 DmaMultiBuffer* buffer = param;
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dma_stop(buffer->dma, buffer->channel);
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buffer->dma_running = false;
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}
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