Save using FFD8

Kweepa · Post by **Kweepa** » Fri Dec 30, 2011 3:59 pm

Hi,
I'm writing some assembly routines to replace cc65's fread and fwrite, because those library functions need 2k of code, presumably mostly to emulate the exact behaviour of the C library functions.
I'm testing in VICE because I don't have a 1541.

Code: Select all

   lda #1    ; logical file
   ldx #8    ; 1 for tape, 8 for disk
   ldy #0    ; secondary address
   jsr $ffba ; setlfs

   lda #8    ; length of name ("savegame")
   ldx #>filename
   ldy #<filename
   jsr $ffbd  ; setnam

   ldx #>start
   ldy #<start
   stx $c1
   sty $c2
   lda #$c1
   ldx #>end
   ldy #<end
   jsr $ffd8

This all works fine, except that if I try to write over the save, it just creates a new file called SAVEGAME.P01 rather than replacing SAVEGAME.P00.

Any advice?

tokra · Post by **tokra** » Fri Dec 30, 2011 4:37 pm

This is standard VICE-behaviour. You should disable the "Write .P00"-option in "Settings-Peripherhal settings" in VICE. Then it will always overwrite the same file. However for a real 1541 this will provide a "FILE EXISTS" error. So you have to use the @: option to overwrite the file, but since this is buggy in the 1541 the only safe way is to delete the file before writing it.

Kweepa · Post by **Kweepa** » Fri Dec 30, 2011 8:42 pm

Thanks, I'll do that!

Here's what I have, to delete a file. It seemed to work first time, which scared me.

Code: Select all

cmd: .text "S:savegame" ; scratch savegame
lda #15
ldx #8 ; disk
ldy #15
jsr $ffba ; SETLFS
lda #10
ldx #>cmd
ldy #<cmd
jsr $ffbd ; SETNAM
jsr $ffc0 ; OPEN
lda #15
jsr $ffbd ; CLOSE