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— base:loading_a_file [2015-04-17 04:32] (current)
Line 1: Line 1:
 +====== Loading a file to memory at address stored in file ======
 +BASIC code:
 +<code>
 +LOAD "JUST A FILENAME",8,1
 +</code>
 +Assembler code:
 +<code>
 +        LDA #fname_end-fname
 +        LDX #<fname
 +        LDY #>fname
 +        JSR $FFBD     ; call SETNAM
 +        LDA #$01
 +        LDX $BA       ; last used device number
 +        BNE .skip
 +        LDX #$08      ; default to device 8
 +.skip   LDY #$01      ; not $01 means: load to address stored in file
 +        JSR $FFBA     ; call SETLFS
 +
 +        LDA #$00      ; $00 means: load to memory (not verify)
 +        JSR $FFD5     ; call LOAD
 +        BCS .error    ; if carry set, a load error has happened
 +        RTS
 +.error
 +        ; Accumulator contains BASIC error code
 +
 +        ; most likely errors:
 +        ; A = $05 (DEVICE NOT PRESENT)
 +        ; A = $04 (FILE NOT FOUND)
 +        ; A = $1D (LOAD ERROR)
 +        ; A = $00 (BREAK, RUN/STOP has been pressed during loading)
 +
 +        ... error handling ...
 +        RTS
 +
 +fname:  .TEXT "JUST A FILENAME"
 +fname_end:
 +</code>
 +
 +
 +
 +====== Loading a file to memory at a specified address======
 +BASIC code:
 +<code>
 +LOAD "JUST A FILENAME",8
 +</code>
 +Assembler code:
 +<code>
 +load_address = $2000  ; just an example
 +
 +        LDA #fname_end-fname
 +        LDX #<fname
 +        LDY #>fname
 +        JSR $FFBD     ; call SETNAM
 +        LDA #$01
 +        LDX $BA       ; last used device number
 +        BNE .skip
 +        LDX #$08      ; default to device 8
 +.skip   LDY #$00      ; $00 means: load to new address
 +        JSR $FFBA     ; call SETLFS
 +
 +        LDX #<load_address
 +        LDY #>load_address
 +        LDA #$00      ; $00 means: load to memory (not verify)
 +        JSR $FFD5     ; call LOAD
 +        BCS .error    ; if carry set, a load error has happened
 +        RTS
 +.error
 +        ; Accumulator contains BASIC error code
 +
 +        ; most likely errors:
 +        ; A = $05 (DEVICE NOT PRESENT)
 +        ; A = $04 (FILE NOT FOUND)
 +        ; A = $1D (LOAD ERROR)
 +        ; A = $00 (BREAK, RUN/STOP has been pressed during loading)
 +
 +        ... error handling ...
 +        RTS
 +
 +fname:  .TEXT "JUST A FILENAME"
 +fname_end:
 +</code>
  
base/loading_a_file.txt ยท Last modified: 2015-04-17 04:32 (external edit)

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