mirror of
https://github.com/cc65/cc65.git
synced 2024-12-28 06:30:16 +00:00
66 lines
1.6 KiB
ArmAsm
66 lines
1.6 KiB
ArmAsm
;
|
|
; Oliver Schmidt, 2012-09-04
|
|
;
|
|
; unsigned char getfirstdevice (void);
|
|
; unsigned char __fastcall__ getnextdevice (unsigned char device);
|
|
;
|
|
|
|
.export _getfirstdevice
|
|
.export _getnextdevice
|
|
.import isdisk
|
|
.import opencmdchannel
|
|
.import closecmdchannel
|
|
.importzp ST
|
|
.importzp tmp2
|
|
|
|
;------------------------------------------------------------------------------
|
|
; _getfirstdevice
|
|
|
|
_getfirstdevice:
|
|
lda #$FF
|
|
; Fall through
|
|
|
|
;------------------------------------------------------------------------------
|
|
; _getnextdevice
|
|
|
|
_getnextdevice:
|
|
tax
|
|
next: inx
|
|
cpx #$FF
|
|
beq done
|
|
|
|
; [open|close]cmdchannel already call isdisk internally but they
|
|
; interpret a non-disk as a no-op while we need to interpret it
|
|
; as an error here
|
|
|
|
jsr isdisk
|
|
bcs next
|
|
|
|
; [open|close]cmdchannel don't call into the Kernal at all if they
|
|
; only [in|de]crement the reference count of the shared cmdchannel
|
|
; so we need to explicitly initialize ST here
|
|
|
|
lda #$00
|
|
sta ST
|
|
|
|
stx tmp2
|
|
jsr opencmdchannel
|
|
ldx tmp2
|
|
jsr closecmdchannel
|
|
ldx tmp2
|
|
|
|
; As we had to reference ST above anyway we can as well do so
|
|
; here too (instead of calling READST)
|
|
|
|
lda ST
|
|
|
|
; Either the Kernal calls above were successfull or there was
|
|
; already a cmdchannel to the device open - which is a pretty
|
|
; good indication of its existence ;-)
|
|
|
|
bmi next
|
|
|
|
done: txa
|
|
ldx #$00
|
|
rts
|