base:loading_a_file
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base:loading_a_file [2015-04-17 04:32] (current) |
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| + | ====== 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)