result=alt_avalon_sgdma_do_async_transfer(sgdma_sd ram, &desc[0])

thanks for your reply~

in short, I want to translate a frame of image by SGDMA, that is, translating 320*230=76800 bytes from FIFO(custom sopc component) to sdram.

according to the manual, alt_avalon_sgdma_construct_mem_to_mem_desc() can translate 65535(length type is alt_u16),so I should use "for-loop"to translate 76800 bytes data.the code is below:

for(buffer_counter=0;buffer_counter<=1;buffer_coun ter++)

{

alt_u32 *write_addr = (alt_u32 *) (DDR_SDRAM_BASE+0xE000*buffer_counter);

alt_avalon_sgdma_construct_mem_to_mem_desc(

&desc[buffer_counter],

&desc[buffer_counter+1],

read_addr,

write_addr,

65535,

1,

0);

}

result=alt_avalon_sgdma_do_async_transfer();

if(!result)

printf("Writing the head of the receive descriptor list to the DMA failed\n");

I use niosII debug mode test the above code,I find that "result" cannot be set to 1 or 0,I donnot know the reason,then I try to change the 65535 to 1024 ,2048..which the translation length is much less than 65530,then I can get the "result" which the value is "0".

in short ,can I translate image data using SGDMA like the above way?which details I have overlook?

thanks !