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blockdev: make "seek" print out its resulting position 

Also, extract commands into blockdev_cmds to avoid making blockdev
dependent on stdio.
This commit is contained in:
Virgil Dupras 2019-04-22 22:54:23 -04:00
parent 5071ee9f40
commit f87cd0485a
2 changed files with 47 additions and 31 deletions
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35
parts/blockdev.asm
View File

@ -44,19 +44,6 @@ blkSel:
pop af
ret
blkBselCmd:
.db "bsel", 0b001, 0, 0
ld a, (hl) ; argument supplied
cp BLOCKDEV_COUNT
jr nc, .error ; if selection >= device count, error
call blkSel
xor a
ret
.error:
ld a, BLOCKDEV_ERR_OUT_OF_BOUNDS
ret
; In those routines below, IY is destroyed (we don't push it to the stack). We
; seldom use it anyways...
@ -137,26 +124,12 @@ blkPutC:
ld iyl, 2
jr _blkCall
; Seeks the block device in one of 5 modes, which is the first argument:
; 0 : Move exactly to X, X being the second argument.
; 1 : Move forward by X bytes, X being the second argument
; 2 : Move backwards by X bytes, X being the second argument
; Seeks the block device in one of 5 modes, which is the A argument:
; 0 : Move exactly to X, X being the HL argument.
; 1 : Move forward by X bytes, X being the HL argument
; 2 : Move backwards by X bytes, X being the HL argument
; 3 : Move to the end
; 4 : Move to the beginning
blkSeekCmd:
.db "seek", 0b001, 0b011, 0b001
; First, the mode
ld a, (hl)
inc hl
; HL points to two bytes that contain out address. Seek expects HL
; to directly contain that address.
ld a, (hl)
ex af, af'
inc hl
ld a, (hl)
ld l, a
ex af, af'
ld h, a
; Set position of selected device to the value specified in HL
blkSeek:
ld iyl, 4

43
parts/blockdev_cmds.asm Normal file
View File

@ -0,0 +1,43 @@
; *** REQUIREMENTS ***
; blockdev
; stdio
blkBselCmd:
.db "bsel", 0b001, 0, 0
ld a, (hl) ; argument supplied
cp BLOCKDEV_COUNT
jr nc, .error ; if selection >= device count, error
call blkSel
xor a
ret
.error:
ld a, BLOCKDEV_ERR_OUT_OF_BOUNDS
ret
blkSeekCmd:
.db "seek", 0b001, 0b011, 0b001
; First, the mode
ld a, (hl)
inc hl
push af ; save mode for later
; HL points to two bytes that contain out address. Seek expects HL
; to directly contain that address.
ld a, (hl)
ex af, af'
inc hl
ld a, (hl)
ld l, a
ex af, af'
ld h, a
pop af ; bring mode back
call blkSeek
ld hl, 42
call blkTell
ld a, h
call printHex
ld a, l
call printHex
call printcrlf
xor a
ret