Re: Calculating checksums...

On Mar 14, 3:33 pm, Alex Buell wrote:

> I have a snippet of FASM code:
>
> ; The last byte (512th) will be the patch_byte for the checksum
> ; patch_byte is calculated and automagically inserted below
> PREV_CHKSUM = 0
> repeat $
>    load CHKSUM byte from %-1
>    CHKSUM = (PREV_CHKSUM + CHKSUM) mod 0x100
>    PREV_CHKSUM = CHKSUM
> end repeat
> store byte (0x100 - CHKSUM) at ($-1)  ; store the patch_byte
>
> How would you suggest I could rewrite this in NASM?

That's easy, just replace the "N" with "F".

http://flatassembler.net/

Seriously though, NASM is an excellent assembler, however
the macro facilities of FASM directly interface the assembly
process and are not merely a preprocess. This example only
reveals the tip of the iceberg.


Mike Gonta
look and see - many look but few see

http://mikegonta.com