RE: Moving data within Flash

sam wagner — Thu, 06 Nov 2014 19:46:44 GMT

Hi Charles,

Thanks a lot for the information. I agree that moving data within Flash is possible.

My question is mostly about if/how pstorage functions can be used to achieve that especially if the data size is large (spanning multiple pages)? If I look at pstorage_update(), it doesn't seem to consider the possibility of pSrc lying in Flash and of data size spanning multiple pages. If pSrc lies in Flash, the swap page usage could get tricky if pDest and pSrc lie within the same page. In that case, one may need to maintain 2 swap pages for tracking the data source and data destination locations during the copy procedure.

Is there an easy way to move large chunk of data from one location in Flash to another location within Flash?

Your insights are most welcome!

Thanks, Sam

RE: Moving data within Flash

Charles Manning — Thu, 06 Nov 2014 19:07:43 GMT

I can't see any reason you cannot copy flash to flash.

The flash writes stall the CPU, but that does not matter.

The ARM cores cannot write directly from any memory to any memory, they load the data into a register first.

ie.

a = b

becomes

load a into register

store register into b

This means all flash writes ultimately become a store command and it really does not matter where the data comes from.

ie. it should be just the same to store the data from RAM, flash, serial port,...