71 lines
1.9 KiB
Z80 Assembly
71 lines
1.9 KiB
Z80 Assembly
|
.global scan_cards
|
||
|
|
.global find_first_card
|
||
|
|
.global get_all_cards
|
||
|
|
|
||
|
|
scan_cards:
|
||
|
|
; Read the types of all the cards in the system
|
||
|
|
; The values in HL, BC, and A are destroyed
|
||
|
|
ld hl, card_types+255
|
||
|
|
ld bc, 0xFFFF ; Start at card 255
|
||
|
|
scan_loop: ; Read the types of card 255 through to card 1
|
||
|
|
in a, (c)
|
||
|
|
ld (hl), a
|
||
|
|
dec hl
|
||
|
|
djnz scan_loop
|
||
|
|
in a, (c) ; Read card 0's type
|
||
|
|
ld (hl), a
|
||
|
|
ret
|
||
|
|
|
||
|
|
get_all_cards:
|
||
|
|
; Gets the indexes of the cards with the specified type
|
||
|
|
; IX is a pointer to the buffer to store the results in
|
||
|
|
; B is the length of the buffer (0 is a 256 byte length)
|
||
|
|
; C is the type of card to find
|
||
|
|
; The zero flag is set if the buffer is full
|
||
|
|
; The values in A, B, HL, and IX are destroyed
|
||
|
|
ld hl, card_types+1
|
||
|
|
gac_loop:
|
||
|
|
ld a, (hl) ; Get card type
|
||
|
|
cp c ; Check whether the type of the current card is the type we want
|
||
|
|
jp nz, gac_next ; Skip the card if it is not
|
||
|
|
ld (ix), l
|
||
|
|
inc ix
|
||
|
|
dec b
|
||
|
|
gac_next:
|
||
|
|
inc hl ; Go to the next card
|
||
|
|
ld a, l ; Check if we have gone through all the cards
|
||
|
|
or a ; (or a == cp 0)
|
||
|
|
jp Z, gac_done ; If so, return
|
||
|
|
ld a, b ; Check if we have filled the buffer
|
||
|
|
or a ; (or a == cp 0)
|
||
|
|
jp Z, gac_full ; If so, return with the zero flag set
|
||
|
|
jp gac_loop
|
||
|
|
gac_done:
|
||
|
|
or 1 ; Reset zero flag to provide correct "buffer filed" indication
|
||
|
|
gac_full:
|
||
|
|
ret
|
||
|
|
|
||
|
|
find_first_card:
|
||
|
|
; Finds the first instance of a card type specified in B
|
||
|
|
; A is zero if no such card was found, and nonzero if a card was found
|
||
|
|
; If a card was found, the ID of the card is returned in L
|
||
|
|
; If a card was not found, 0 is returned in L
|
||
|
|
; The values in A and H are destroyed
|
||
|
|
ld hl, card_types+1
|
||
|
|
ffc_loop:
|
||
|
|
ld a, (hl) ; Get card type
|
||
|
|
cp b ; Check whether the type of the current card is the type we want
|
||
|
|
jp Z, ffc_done ; If so, return the type in L
|
||
|
|
or a ; (or a == cp 0) Check whether the card type is 0 (nonexistent card)
|
||
|
|
jp Z, ffc_notfound ; If so, return 0 in L
|
||
|
|
inc hl ; Go to the next card
|
||
|
|
jp ffc_loop
|
||
|
|
ffc_notfound:
|
||
|
|
ld l, 0
|
||
|
|
ffc_done:
|
||
|
|
ret
|
||
|
|
|
||
|
|
.bss
|
||
|
|
.balign 256
|
||
|
|
card_types: .ds.b 256
|