我正在尝试学习如何在此
Codebase64 Tutorial之后使用kernal例程来编写磁盘文件.
我复制了我的例程,用Acme Crossassembler编写,下面.它无法打开文件并显示错误消息：“FILE NOT OPENED”
; Definitions
SETNAM = $FFBD
SETFLS = $FFBA
OPEN = $FFC0
CHKOUT = $FFC9
READST = $FFB7
CLOSE = $FFC3
CLRCHN = $FFCC
CHROUT = $ffd2
;Basic Start
* = $0801 ; BASIC start address (#2049)
!byte $0d,$08,$dc,$07,$9e,$20,$34,$39 ; BASIC loader to start at $c000...
!byte $31,$35,$32,$00,$00 ; puts BASIC line 2012 SYS 49152
;Program Code
* = $c000 ; Can be executed by writing sys 49152
ldx #<message0
ldy #>message0
jsr printMessage
save2file:
; call SETNAM
lda #fname_end-fname ; file name size
ldx #<fname ; file name vector
ldy #>fname ; file name vector
jsr SETNAM ; call SETNAM
; call SETFLS
lda #$00
ldx $BA ; last used device number
bne +
ldx #$08 ; default to device 8
+ ldy #$00
jsr SETFLS ; call SETLFS
;call OPEN
jsr OPEN ; call OPEN
bcs .error1 ; if carry set,the file could not be opened
; call CHKOUT
ldx #$02 ; filenumber=2
jsr CHKOUT ; file 2 now used as output
; Copy border color to the file
jsr READST ; call READST (read status byte)
bne .error2 ; write error
lda $d020 ; get byte from memory
jsr CHROUT ; write to file
ldx #<message1
ldy #>message1
jsr printMessage
.close
lda #$02 ; filenumber 2
jsr CLOSE ; call CLOSE
jsr CLRCHN ; call CLRCHN
rts
.error1
ldx #<errorMsg1
ldy #>errorMsg1
jsr printMessage
jmp .close
.error2
ldx #<errorMsg2
ldy #>errorMsg2
jsr printMessage
jmp .close
fname: !tx "DATA,S,W"
fname_end:
message0: !by 141 : !scr"SAVING" : !by 0
message1: !by 141 : !scr"COLORS SAVED" : !by 0
errorMsg1: !by 141 : !scr"FILE NOT OPENED" : !by 0
errorMsg2: !by 17 : !scr"WRITE ERROR" : !by 0
;==========================================================================
; printMessage
; Prints null terminated string to the memory
; Input: x,y adress vector of text string
;==========================================================================
temp = $fb ;zero page pointer
printMessage:
stx temp ;save string pointer LSB
sty temp+1 ;save string pointer MSB
ldy #0 ;starting string index
- lda (temp),y ;get a character
beq + ;end of string
jsr CHROUT ;print character
iny ;next
bne -
inc temp+1
bne -
+ rts
我已经使用C64 Programmer’s Reference准备了下面列出的Basic Routine.它在同一环境中按预期工作.
10 OPEN 3,8,3,"O:DATA FILE,W" 20 PRINT#3,"SENT TO DISK" 30 CLOSE 3
那么,为什么我的asm例程不起作用？
我正在测试Vice 2.4
解决方法
显然问题出现在逻辑数字和次要地址中,如J所示…
我通过更换零件来修复它.i.e：
; call SETFLS
lda #$03
ldx $BA ; last used device number
bne +
ldx #$08 ; default to device 8
+ ldy #$03
jsr SETFLS ; call SETLFS
…
; call CHKOUT
ldx #$03 ; filenumber=3
jsr CHKOUT ; file 2 now used as output
…
.close
lda #$03 ; filenumber 3
jsr CLOSE ; call CLOSE
jsr CLRCHN ; call CLRCHN
rts
还有其他问题,如“COLORS SAVED”消息被发送到文件而不是屏幕,但这些可以很容易地修复.
