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cc65/libsrc/cbm/diskcmd.s
uz 828b4226cf Comment additions and changes.
git-svn-id: svn://svn.cc65.org/cc65/trunk@3942 b7a2c559-68d2-44c3-8de9-860c34a00d81
2009-02-22 14:42:32 +00:00

236 lines
6.2 KiB
ArmAsm

;
; Ullrich von Bassewitz, 2002-11-17, 2009-02-22
;
; Handle disk command channels
;
.export isdisk
.export opencmdchannel
.export closecmdchannel
.export readdiskerror
.export writediskcmd
.export writefndiskcmd
.import SETLFS, SETNAM, OPEN, CLOSE, BSOUT, BASIN
.import CHKIN, CKOUT, CLRCH
.import fncmd, fnlen, fnunit
.importzp tmp1, ptr1
.include "cbm.inc"
.include "filedes.inc"
;--------------------------------------------------------------------------
; isdisk: Return carry clear if the unit number in X is a disk, return
; carry set if not.
.proc isdisk
cpx #FIRST_DRIVE ; Disk unit?
bcc @L1 ; Branch if no disk
cpx #FIRST_DRIVE+MAX_DRIVES
rts
@L1: sec
rts
.endproc
;--------------------------------------------------------------------------
; Open the command channel for the disk unit in X. The function returns an
; error code in A and sets the flags according to the contents of A.
opencmdchannel:
jsr isdisk ; Disk unit?
bcs success
; Is this channel already open?
ldy opentab-FIRST_DRIVE,x
bne isopen
; Open the command channel, Carry is still clear
stx tmp1 ; Save the unit number
txa ; Get unit number
adc #(LFN_OFFS+MAX_FDS-FIRST_DRIVE)
ldy #15 ; Secondary address for cmd channel
jsr SETLFS
lda #0
jsr SETNAM ; No name supplied to OPEN
jsr OPEN
bcs done ; Error, code is in A
; Command channel is open now. Increment the count
ldx tmp1 ; Unit number
ldy opentab-FIRST_DRIVE,x
isopen: iny
tya
sta opentab-FIRST_DRIVE,x
; Done, return success
success:lda #$00
done: cmp #$00 ; Set flags for return code
rts
;--------------------------------------------------------------------------
; closecmdchannel: Decrement the counter for the disk command channel and
; close the channel if the counter drops to zero. The function expects the
; drive number in X and returns an error code in A. The flags for the return
; code are set when the function returns.
closecmdchannel:
jsr isdisk ; Disk unit?
bcs success
; Is this channel really open?
ldy opentab-FIRST_DRIVE,x
beq success ; OOPS! Channel is not open
; Decrement the count and stor it back
dey
tya
sta opentab-FIRST_DRIVE,x
; If the counter is now zero, close the channel. We still have carry clear
; when we come here.
bne success
txa ; Make LFN from drive number
adc #(LFN_OFFS+MAX_FDS-FIRST_DRIVE)
jsr CLOSE
bcs done
bcc success
;--------------------------------------------------------------------------
; readdiskerror: Read a disk error from an already open command channel.
; Returns an error code in A, which may either be the code read from the
; command channel, or another error when accessing the command channel failed.
readdiskerror:
jsr isdisk
bcs success
; Read the command channel. We won't check the status after the channel is
; open, because this seems to be unnecessary in most cases.
txa
clc ; Make LFN from drive number
adc #(LFN_OFFS+MAX_FDS-FIRST_DRIVE)
tax
jsr CHKIN ; Make the command channel input
bcs done ; Bail out with error code in A
jsr BASIN
and #$0F ; Make digit value from PETSCII
sta tmp1
asl a ; * 2
asl a ; * 4, carry clear
adc tmp1 ; * 5
asl a ; * 10
sta tmp1
jsr BASIN
and #$0F ; Make digit value from PETSCII
clc
adc tmp1
; Errors below 20 are not real errors. Fix that
cmp #20+1
bcs @L1
lda #$00
@L1: pha
; Read the remainder of the message and throw it away
@L2: jsr BASIN
cmp #$0D
bne @L2
; Close the input channel
jsr CLRCH
; Restore the error code (will also set the flags) and return
pla
rts
;--------------------------------------------------------------------------
; writefndiskcmd: Write the contents of fncmd to the command channel of the
; drive in fnunit. Returns an error code in A, flags are set according to
; the contents of A.
writefndiskcmd:
lda #<fncmd
sta ptr1
lda #>fncmd
sta ptr1+1
ldx fnlen
inx ; Account for command char in fncmd
txa ; Length of name into A
ldx fnunit ; Unit
; Run directly into writediskcmd
; jmp writediskcmd
;--------------------------------------------------------------------------
; writediskcmd: Gets pointer to data in ptr1, length in A. Writes all data
; to the command channel of the drive in X. Returns an error code in A,
; flags are set according to the contents of A.
writediskcmd:
jsr isdisk
bcs success ; No disk - already done
; Remember the length
sta tmp1
; Write to the command channel.
txa
clc ; Make LFN from drive number
adc #(LFN_OFFS+MAX_FDS-FIRST_DRIVE)
tax
jsr CKOUT ; Make the command channel output
bcs done ; Bail out with error code in A
ldy #$00
@L1: cpy tmp1
bcs @L3
lda (ptr1),y
iny
jsr BSOUT
bcc @L1
@L2: pha
jsr CLRCH
pla
rts
@L3: jsr CLRCH
lda #$00
rts
;--------------------------------------------------------------------------
; Data
.bss
opentab: .res MAX_DRIVES, 0