MAC7200 datasheet(283/976 Pages) FREESCALE

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The SPP DMA Controller Module (SPP_DMA2)

MAC7200 Microcontroller Family Reference Manual, Rev. 2

Freescale Semiconductor

205

break;

case 2:

/* 32-bit transfer */

dest_xfr_size = 4;

break;

case 3:

/* 64-bit transfer */

dest_xfr_size = 8;

break;

case 4:

/* 16-byte burst transfer */

dest_xfr_size = 16;

break;

case 5:

/* 32-byte burst transfer */

dest_xfr_size = 32;

break;

}

/* determine the larger of the two transfer sizes, this value reflects */

/* the number of bytes transferred per read->write sequence. */

/* number of iterations of the minor loop = nbytes / xfer_size */

if (dma_engine.ssize < dma_engine.dsize)

xfr_size = dest_xfer_size;

else

xfr_size = src_xfer_size;

/* process the source address, READ data into the buffer*/

/* read “xfr_size” bytes from the source */

/* if the ssize < dsize, do multiple reads to equal the dsize */

/* if the ssize => dsize, do a single read of source data */

number_of_source_reads = xfer_size / src_xfer_size;

for (number_of_source_reads) {

dma_engine.data = read_from_amba-ahb (dma_engine.saddr, src_xfr_size);

/* generate the next-state source address */

/* sum the current saddr with the signed source offset */

ns_addr = dma_engine.saddr + (int) dma_engine.soff; }

/* if enabled, apply the power-of-2 modulo to the next-state addr */

if (dma_engine.smod != 0)

address_select = (1 << dma_engine.smod) - 1; }

else

address_select = 0xffff_ffff;

dma_engine.saddr = ns_addr

address_select

| dma_engine.saddr & ~address_select; }

}

/* process the destination address, WRITE data from buffer */

/* write “xfr_size” bytes to the destination */

/* if the dsize < ssize, do multiple writes to equal the ssize */

/* if the dsize => ssize, do a single write of dest data */

number_of_dest_writes = xfer_size / dest_xfer_size;

for (number_of_dest_writes) {

write_to_amba-ahb (dma_engine.daddr, dest_xfr_size) = dma_engine.data;

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