at28wMain:
ld de, AT28W_MAXBYTES
ld a, (hl)
or a
jr z, at28wInner ; no arg
call parseHexadecimal ; --> DE
jr z, at28wInner
; bad args
ld a, SHELL_ERR_BAD_ARGS
ret
at28wInner:
; Reminder: words in parseArgs aren't little endian. High byte is first.
ld a, (AT28W_MAXBYTES)
ld b, a
ld a, (AT28W_MAXBYTES+1)
ld c, a
ld hl, AT28W_MEMSTART
call at28wBCZero
jr nz, .loop
; BC is zero, default to 0x2000 (8k, the size of the AT28)
ld bc, 0x2000
loop:
call blkGetB
jr nz, .loopend
ld (hl), a
ld e, a ; save expected data for verification
; initiate polling
ld a, (hl)
ld d, a
wait:
; as long as writing operation is running, IO/6 will toggle at each
; read attempt. We know that write is finished when we read the same
; value twice.
ld a, (hl)
cp d
jr z, .waitend
ld d, a
jr .wait
waitend:
; same value was read twice. A contains our final value for this memory
; address. Let's compare with what we're written.
cp e
jr nz, .mismatch
inc hl
dec bc
call at28wBCZero
jr nz, .loop
