Steins7
fd33003e26
DMA buffers now work reliably with USART. The DMA api has changed to make it more efficient code-size-wise. This may, however, complicate things when implementating powersaving features
76 lines
2.4 KiB
C
76 lines
2.4 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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#ifndef _DMA_MBUF_H_
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#define _DMA_MBUF_H_
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//--includes--------------------------------------------------------------------
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#include "../drv/dma.h"
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//--type definitions------------------------------------------------------------
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/**
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* Struct used by the multibuffer system. This system allows bufferized writes
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* to a peripheral with no latency, minimal cpu usage and customisable buffer
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* sizes
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*/
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struct DmaMultiBuffer {
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uint8_t* raw_buffer;
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uint16_t buffer_size;
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uint8_t byte_index;
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uint8_t buffer_index;
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enum DmaPeriph dma;
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enum DmaChannel channel;
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bool dma_running;
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};
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//--functions-------------------------------------------------------------------
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/**
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* Configure a DMA multibuffer for a single DMA channel. A list of buffers is
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* used to allow concurent write and DMA tranfers to the specified destination
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* wich must be a peripheral. The DMA's priority is also given as parameters.
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* The peripheral's specific configuration must be handled separately. 2 bytes
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* are reserved in each buffer for index storage.
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*
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* This system needs to be started manually: dma_mbuf_refresh() should be called
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* whenever a DMA transfer can be started. This can be done manually after
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* filling up the buffer. Transfers will then automatically be started as long
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* as there are bytes in the buffer. See the usart module for an usage exemple
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*/
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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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* Write the given byte to the given buffer. Returns 0 if the write operation
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* was successfull, 1 otherwise. The function is non-blocking.
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*
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* Note: calling this function will not trigger a DMA transfer, see
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* dma_mbuf_refresh() to do that
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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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* Refresh the buffer state, checking for bytes to send and triggering a DMA
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* transfer if necessary. Should be called for the first transfer, any remaining
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* transfer will be handled automatically until there are no bytes left in the
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* buffer
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*/
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void dma_mbuf_switch(volatile struct DmaMultiBuffer* buffer);
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#endif //_DMA_MBUF_H_
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