297 lines
5.5 KiB
ArmAsm
297 lines
5.5 KiB
ArmAsm
; File I/O routines based on sample code in
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; "Beneath Apple DOS" by Don Worth and Pieter Lechner
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;; For the disk-read code
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;RWTSL EQU $F0
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;RWTSH EQU $F1
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;DOSBUFL EQU $EE
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;DOSBUFH EQU $EF
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;FILEML EQU $EC
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;FILEMH EQU $ED
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;; DOS Constants
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OPEN EQU $01
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CLOSE EQU $02
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READ EQU $03
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WRITE EQU $04
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DELETE EQU $05
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CATALOG EQU $06
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LOCK EQU $07
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UNLOCK EQU $08
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RENAME EQU $09
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POSITION EQU $0A
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INIT EQU $0B
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VERIFY EQU $0C
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LOCATE_FILEM_PARAM EQU $3DC
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LOCATE_RWTS_PARAM EQU $3E3
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FILEMANAGER EQU $3D6
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;================================
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; read from disk
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;================================
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; FILENAME pointed to by INH:INL
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; OUTH:OUTL trashed
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; output buffer: disk_buff
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; size to read: read_size
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read_file:
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jsr LOCATE_FILEM_PARAM ; $3DC entry point
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; load file manager param list
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; returns Y=low A=high
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sta FILEMH
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sty FILEML
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; ldy #7 ; file type offset = 7
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; lda #0 ; 0 = text
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; sta (FILEML),y
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; copy filename into place
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ldy #0
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lda #<filename ; combine with below? (filename-8?)
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sta OUTL
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lda #>filename
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sta OUTH
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filename_copy_loop:
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lda (INL),y ; load byte
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beq filename_pad_spaces ; if zero, done
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ora #$80 ; convert to apple ascii
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sta (OUTL),y ; store out
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iny
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bne filename_copy_loop
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filename_pad_spaces:
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lda #$A0 ; filename needs ' ' padded
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sta (OUTL),y
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iny
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cpy #30 ; fill 30 bytes
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bne filename_pad_spaces
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filename_pad_done:
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ldy #8 ; filename ptr offset = 8
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lda #<filename
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sta (FILEML),y
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iny
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lda #>filename
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sta (FILEML),y
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ldx #1 ; open existing file
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jsr dos33_open ; open file
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bcs error_open
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jsr dos33_read ; read buffer
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bcc now_close
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; got an error
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; error 05 is OK (OUT OF DATA)
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; because we try to read too much
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ldy #$a
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lda (FILEML),Y
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cmp #5
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beq now_close
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jmp error_read
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now_close:
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jsr dos33_close ; close file
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bcs error_close
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rts
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error_open:
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lda #$f5
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brk
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error_read:
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ldy #$a
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lda (FILEML),y
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tay
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lda #$f6
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brk
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error_close:
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lda #$f7
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brk
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;=================================
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; get_dos_buffer
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;=================================
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;
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; Dos buffer format
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; 0x000-0x0ff = data buffer
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; 0x100-0x1ff = t/s list buffer
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; 0x200-0x22c = file manager workarea (45 bytes)
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; 0x22d-0x24a = file name buffer
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; 0x24b-0x24c = address of file manager workarea
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; 0x24d-0x24e = address of t/s list buffer
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; 0x24f-0x250 = adress of data sector buffer
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; 0x251-0x252 = address of file name field for the next buffer
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; In DOS, $3D2 points to 0x22d of first buffer
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; add 0x24 to get chain pointer
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dos33_open:
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; allocate one of the DOS buffers so we don't have to set them up
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allocate_dos_buffer:
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lda $3D2 ; DOS load point
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sta DOSBUFH
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ldy #0
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sty DOSBUFL
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buf_loop:
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lda (DOSBUFL),Y ; locate next buffer
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pha ; push on stack
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; we need this later
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; to test validity
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iny ; increment y
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lda (DOSBUFL),Y ; load next byte
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sta DOSBUFH ; store to buffer pointerl
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pla ; restore value from stack
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sta DOSBUFL ; store to buffer pointerh
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bne found_buffer ; if not zero, found a buffer
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lda DOSBUFH ; also if not zero, found a buffer
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bne found_buffer ; no buffer found, exit
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sec ; failed
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rts
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found_buffer:
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ldy #0 ; get filename
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lda (DOSBUFL),Y ; get first byte
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beq good_buffer ; if zero, good buffer
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; in use
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ldy #$24 ; point to next
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bne buf_loop ; and loop
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good_buffer:
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lda #$78
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sta (DOSBUFL),Y ; mark as in use (can be any !0)
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keep_opening:
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ldy #0
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lda #OPEN ; set operation code to OPEN
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sta (FILEML),y
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ldy #2 ; point to record length
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lda #0 ; set it to zero (16-bits)
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sta (FILEML),y
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iny
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sta (FILEML),y
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iny ; point to volume num (0=any)
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sta (FILEML),y
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jsr LOCATE_RWTS_PARAM ; get current RWTS parameters
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; so we can get disk/slot info
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sty RWTSL
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sta RWTSH
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ldy #1
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lda (RWTSL),y ; get slot*16
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lsr a
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lsr a
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lsr a
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lsr a ; divide by 16
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ldy #6 ; address of slot
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sta (FILEML),y ; store it
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ldy #2
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lda (RWTSL),y ; get drive
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ldy #5 ; address of drive
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sta (FILEML),y
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filemanager_interface:
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ldy #$1E
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dbuf_loop:
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lda (DOSBUFL),y ; get three buffer pointers
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pha ; push onto stack
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iny ; increment pointer
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cpy #$24 ; have we incremented 6 times?
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bcc dbuf_loop ; if not, loop
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ldy #$11 ; point to the end of the same struct
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; in file manager
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fmgr_loop:
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pla ; pop value
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sta (FILEML),Y ; store it
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dey ; work backwards
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cpy #$c ; see if we are done
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bcs fmgr_loop ; loop
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jmp FILEMANAGER ; #3D6
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; run filemanager
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; will return for us
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;====================
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; close DOS file
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;====================
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dos33_close:
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ldy #0 ; command offset
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lda #CLOSE ; load close
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sta (FILEML),y
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jsr filemanager_interface
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bcs error_close
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ldy #0 ; mark dos buffer as free again
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tya
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sta (DOSBUFL),y
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rts
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;=========================
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; read from dos file
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;=========================
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dos33_read:
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ldy #0 ; command offset
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lda #READ
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sta (FILEML),y
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iny ; point to sub-opcode
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lda #2 ; "range of bytes"
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sta (FILEML),y
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ldy #6 ; point to number of bytes to read
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lda #<read_size
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sta (FILEML),y ; we want to read read_size bytes
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iny
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lda #>read_size
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sta (FILEML),y
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ldy #8 ; buffer address
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lda #<disk_buff
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sta (FILEML),y
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iny
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lda #>disk_buff
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sta (FILEML),y
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jmp filemanager_interface
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filename:
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; OUT.0
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.byte 'I'+$80,'N'+$80,'T'+$80,'R'+$80,'O'+$80
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.byte '2'+$80,'.'+$80,'K'+$80,'R'+$80,'W'+$80
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.byte $A0,$A0,$A0,$A0,$A0
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.byte $A0,$A0,$A0,$A0,$A0
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.byte $A0,$A0,$A0,$A0,$A0
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.byte $A0,$A0,$A0,$A0,$A0
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