mirror of
https://github.com/bobbimanners/Applecorn.git
synced 2024-11-05 02:08:07 +00:00
152 lines
3.5 KiB
ArmAsm
152 lines
3.5 KiB
ArmAsm
* MAINMEM.LDR.S
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* (c) Bobbi 2021 GPLv3
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*
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* Applecorn loader code. Runs in main memory.
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* Loads Acorn ROM file (16KB) from disk and writes it
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* to aux memory starting at $08000. Copies Applecorn MOS
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* to aux memory starting at AUXMOS1 and jumps to it.
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* (Note that the MOS code will copy itself to $D000.)
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START JSR ROMMENU
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STZ :BLOCKS
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LDX #$00
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:S1 JSR CROUT
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JSR SETPRFX
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JSR DISCONN
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LDA #$20 ; PAGE2 shadow on ROM3 GS
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TRB $C035
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JSR OPENFILE ; Open ROM file
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BCC :S2
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LDX #$00
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:L2 LDA CANTOPEN,X
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BEQ :ER1
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JSR COUT1
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INX
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BRA :L2
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BRA :S2
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:ER1 JSR CROUT
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JSR BELL
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RTS
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:S2 LDA OPENPL+5 ; File reference number
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STA READPL+1
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:L3 LDA #'.'+$80 ; Read file block by block
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JSR COUT1
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JSR RDFILE
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BCS :S3 ; EOF (0 bytes left) or some error
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LDA #<BLKBUF ; Source start addr -> A1L,A1H
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STA A1L
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LDA #>BLKBUF
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STA A1H
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LDA #<BLKBUFEND ; Source end addr -> A2L,A2H
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STA A2L
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LDA #>BLKBUFEND
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STA A2H
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LDA #<AUXADDR ; Dest in aux -> A4L, A4H
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STA A4L
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LDA #>AUXADDR
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LDX :BLOCKS
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:L4 CPX #$00
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BEQ :S25
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INC
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INC
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DEX
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BRA :L4
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:S25 STA A4H
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SEC ; Copy Main -> Aux
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JSR AUXMOVE
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INC :BLOCKS
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BRA :L3
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:S3 LDA OPENPL+5 ; File reference number
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STA CLSPL+1
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JSR CLSFILE
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LDA #<MOSSHIM ; Start address of MOS shim
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STA A1L
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LDA #>MOSSHIM
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STA A1H
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LDA #<MOSSHIM+$2000 ; End address of MOS shim
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STA A2L
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LDA #>MOSSHIM+$2000
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STA A2H
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LDA #<AUXMOS1 ; To AUXMOS1 in aux memory
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STA A4L
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LDA #>AUXMOS1
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STA A4H
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SEC ; Copy MOS from Main->Aux
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JSR AUXMOVE
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LDA #<RESET ; Set reset vector->RESET
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STA RSTV
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LDA #>RESET
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STA RSTV+1
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EOR #$A5 ; Checksum
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STA RSTV+2
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LDA #<GSBRK ; Set BRK vector in main mem
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STA $3F0
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LDA #>GSBRK
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STA $3F0+1
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* LDA $C057 ; Enable hi-res
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* LDA $C054 ; Enable page 1
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* LDA $C050 ; Enable graphics
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JSR Entry+0 ; Initialize FDRAW library
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LDA #$20
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STA Entry+5
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JSR Entry+19 ; FDRAW: Set page $2000
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JSR Entry+22 ; FDRAW: clear HGR screen
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* LDA $C051 ; Enable text again
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TSX ; Save SP at $0100 in aux
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STA $C005 ; Write to aux
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STX $0100
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STA $C004 ; Write to main
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>>> XF2AUX,AUXMOS1
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:BLOCKS DB 0 ; Counter for blocks read
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CANTOPEN ASC "Unable to open ROM file"
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DB $00
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