typedef struct DMA_DSCR
{
void *saddr;
void *daddr;
u_int ctrla;
u_int ctrlb;
struct DMA_DSCR *dscr;
} DMA_DSCR;


#pragma arm section zidata = "extsram"
__align(4) u_char audio_buffers[AUDIO_BUFFERS][AUDIO_BUFFER_SIZE];
#pragma arm section zidata

DMA_DSCR audio_dscrs[AUDIO_BUFFERS];


//******************************************************************************
//*

#define AUDIO_DMA_CTRLA (AT91C_HDMA_DST_WIDTH_WORD | AT91C_HDMA_SRC_WIDTH_WORD | \
AT91C_HDMA_DCSIZE_4 | AT91C_HDMA_SCSIZE_1 | (AUDIO_BUFFER_SIZE / 4))
#define AUDIO_DMA_CTRLB (AT91C_HDMA_FC_PER2MEM | AT91C_HDMA_SRC_ADDRESS_MODE_FIXED | AT91C_HDMA_SRC_DSCR_FETCH_DISABLE)

void audio_start_dma(void)
{
u_int a;


*AT91C_HDMA_CHDR = AT91C_HDMA_ENA0 << AUDIO_DMA_CH;

for(a = 0; a < AUDIO_BUFFERS; a++)
{
audio_dscrs[a].saddr = (void *)AT91C_SSC0_RHR;
audio_dscrs[a].daddr = audio_buffers[a];
audio_dscrs[a].ctrla = AUDIO_DMA_CTRLA;
audio_dscrs[a].ctrlb = AUDIO_DMA_CTRLB;
audio_dscrs[a].dscr = (a == (AUDIO_BUFFERS - 1)) ? &audio_dscrs[0] : &audio_dscrs[a + 1];
}

AT91C_BASE_HDMA->HDMA_CH[AUDIO_DMA_CH].HDMA_SADDR = (u_int)audio_dscrs[AUDIO_BUFFERS - 1].saddr;
AT91C_BASE_HDMA->HDMA_CH[AUDIO_DMA_CH].HDMA_DADDR = (u_int)audio_dscrs[AUDIO_BUFFERS - 1].daddr;
AT91C_BASE_HDMA->HDMA_CH[AUDIO_DMA_CH].HDMA_CTRLA = audio_dscrs[AUDIO_BUFFERS - 1].ctrla;
AT91C_BASE_HDMA->HDMA_CH[AUDIO_DMA_CH].HDMA_CTRLB = audio_dscrs[AUDIO_BUFFERS - 1].ctrlb;
AT91C_BASE_HDMA->HDMA_CH[AUDIO_DMA_CH].HDMA_DSCR = (u_int)audio_dscrs[AUDIO_BUFFERS - 1].dscr;

AT91C_BASE_HDMA->HDMA_CH[AUDIO_DMA_CH].HDMA_CFG = AT91C_HDMA_FIFOCFG_HALFFIFO | AT91C_HDMA_AHB_PROT |
AT91C_HDMA_SOD | AT91C_HDMA_SRC_H2SEL_HW | SSC_RX_DMA_IF_NUM;

*AT91C_HDMA_EBCIER = (AT91C_HDMA_BTC0 << AUDIO_DMA_CH) | (AT91C_HDMA_ERR0 << AUDIO_DMA_CH);

*AT91C_HDMA_CHER = AT91C_HDMA_ENA0 << AUDIO_DMA_CH;
}