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blockdev: make zasm-friendly

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This commit is contained in:
Virgil Dupras 2019-05-17 14:06:10 -04:00
parent 3a91e9eb46
commit b8ece0bf98
1 changed files with 19 additions and 15 deletions
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34
parts/z80/blockdev.asm
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@ -45,24 +45,24 @@
; BLOCKDEV_COUNT: The number of devices we manage.
; *** CONSTS ***
BLOCKDEV_ERR_OUT_OF_BOUNDS .equ 0x03
BLOCKDEV_ERR_UNSUPPORTED .equ 0x04
.equ BLOCKDEV_ERR_OUT_OF_BOUNDS 0x03
.equ BLOCKDEV_ERR_UNSUPPORTED 0x04
BLOCKDEV_SEEK_ABSOLUTE .equ 0
BLOCKDEV_SEEK_FORWARD .equ 1
BLOCKDEV_SEEK_BACKWARD .equ 2
BLOCKDEV_SEEK_BEGINNING .equ 3
BLOCKDEV_SEEK_END .equ 4
.equ BLOCKDEV_SEEK_ABSOLUTE 0
.equ BLOCKDEV_SEEK_FORWARD 1
.equ BLOCKDEV_SEEK_BACKWARD 2
.equ BLOCKDEV_SEEK_BEGINNING 3
.equ BLOCKDEV_SEEK_END 4
; *** VARIABLES ***
; Pointer to the selected block device. A block device is a 8 bytes block of
; memory with pointers to GetC, PutC, Seek and Tell routines, in that order.
; 0 means unsupported.
BLOCKDEV_GETC .equ BLOCKDEV_RAMSTART
BLOCKDEV_PUTC .equ BLOCKDEV_GETC+2
BLOCKDEV_SEEK .equ BLOCKDEV_PUTC+2
BLOCKDEV_TELL .equ BLOCKDEV_SEEK+2
BLOCKDEV_RAMEND .equ BLOCKDEV_TELL+2
.equ BLOCKDEV_GETC BLOCKDEV_RAMSTART
.equ BLOCKDEV_PUTC BLOCKDEV_GETC+2
.equ BLOCKDEV_SEEK BLOCKDEV_PUTC+2
.equ BLOCKDEV_TELL BLOCKDEV_SEEK+2
.equ BLOCKDEV_RAMEND BLOCKDEV_TELL+2
; *** CODE ***
; Select block index specified in A and place them in routine pointers at (DE).
@ -120,15 +120,19 @@ _blkCall:
; Before we call... is IX zero? We don't want to call a zero.
push af
xor a
cp ixh
push hl
push ix \ pop hl
cp h
jr nz, .ok ; not zero, ok
cp ixl
cp l
jr z, .error ; zero, error
.ok:
pop hl
pop af
call callIX
ret
.error:
pop hl
pop af
ld a, BLOCKDEV_ERR_UNSUPPORTED
ret
@ -222,7 +226,7 @@ _blkSeek:
; all other modes are considered absolute
jr .seek ; for absolute mode, HL is already correct
.forward:
ex hl, de ; DE has our offset
ex de, hl ; DE has our offset
; We want to be able to plug our own TELL function, which is why we
; don't call blkTell directly here.
; Calling TELL