mirror of
https://github.com/hsoft/collapseos.git
synced 2024-11-27 21:28:05 +11:00
44 lines
1008 B
NASM
44 lines
1008 B
NASM
; If you find youself needing to write to an EEPROM through a shell that isn't
|
|
; built for this, compile this dependency-less code (change memory offsets as
|
|
; needed) and run it in a USR-like fashion.
|
|
|
|
ld bc, 0x1000 ; bytecount to write
|
|
ld de, 0xd000 ; source data
|
|
ld hl, 0x2000 ; dest EEPROM memory mapping
|
|
|
|
loop:
|
|
ld a, (de)
|
|
ld (hl), a
|
|
push de ; --> lvl 1
|
|
push bc ; --> lvl 2
|
|
ld bc, 0x2000 ; Should be plenty enough to go > 10ms
|
|
ld e, a ; save expected data for verification
|
|
wait:
|
|
; as long as writing operation is running, IO/6 will toggle at each
|
|
; read attempt and IO/7 will be the opposite of what was written. Simply
|
|
; wait until the read operation yields the same value as what we've
|
|
; written
|
|
ld a, (hl)
|
|
cp e
|
|
jr z, waitend
|
|
dec bc
|
|
ld a, b
|
|
or c
|
|
jr nz, wait
|
|
; mismatch
|
|
pop bc ; <-- lvl 2
|
|
pop de ; <-- lvl 1
|
|
ld a, 1 ; nonzero
|
|
or a ; unset Z
|
|
ret
|
|
waitend:
|
|
pop bc ; <-- lvl 2
|
|
pop de ; <-- lvl 1
|
|
inc hl
|
|
inc de
|
|
dec bc
|
|
ld a, b
|
|
or c
|
|
jr nz, loop
|
|
ret ; Z already set
|