dma.cpp

00001 #include "dma.h"
00002 
00003 namespace mbed {
00004 
00005 
00006 DMA::DMA (int priority):
00007 channel_num(_channel_num) 
00008 {
00009     chan = chooseFreeChannel(priority) ;
00010 //    channel_num = _channel_num;
00011     DMA_reset(chan);// reset the register value to default and clear the interrupts
00012     dma_init_struct = DMA_struct_create(); // initialize the dma data structure to default value
00013 }
00014 
00015 
00016 DMA::~DMA()
00017 {
00018     DMA_struct_delete(dma_init_struct);
00019     DMA_IRQ_detach(chan);
00020 }
00021 
00022 // if no channel choosed, choose whichever free channel, otherwise, wait until the channel is free
00023 int DMA::chooseFreeChannel (int channel)
00024 {
00025     int reval=channel;
00026     if (channel > (channel_num-1) || channel < 0) 
00027     {
00028         reval = 0;
00029         while (1) { //if not chosen channel, round robin checked which channel is free
00030             if (!DMA_channel_active(reval))
00031                 return reval;
00032             reval++;
00033             if (reval>(channel_num-1))
00034                 reval=0;
00035         }
00036     } 
00037     else
00038     {
00039         while (DMA_channel_active(reval));//if has chosen the channel, wait until the channel is free
00040     }
00041     
00042     return reval;
00043 }
00044 
00045 void DMA::TriggerSource(TriggerType trig)
00046 {
00047     DMA_trigger_source(dma_init_struct, trig);
00048 }
00049 
00050 void DMA::TriggerDestination(TriggerType trig)
00051 {
00052     DMA_trigger_destination(dma_init_struct, trig);
00053 }
00054 
00055 /*
00056 void DMA::next(LLI* list)
00057 {
00058         DMA_next(dma_init_struct, list);
00059 }
00060 */
00061 
00062 void DMA::next(const uint32_t src, const uint32_t dst, uint32_t size)
00063 {
00064     DMA_next(dma_init_struct, src, dst, size);
00065 }
00066 
00067 void DMA::start (unsigned int len)
00068 {
00069     DMA_init(chan,dma_init_struct);
00070     DMA_start(chan, dma_init_struct, len);
00071 }
00072 
00073 void DMA::wait()
00074 {
00075     while (DMA_channel_active(chan));
00076 }
00077 
00078 bool DMA::finished()
00079 {
00080     return !DMA_channel_active(chan);
00081 }
00082 }