mirror of https://github.com/dschmenk/VM02.git
264 lines
3.6 KiB
ArmAsm
Executable File
264 lines
3.6 KiB
ArmAsm
Executable File
;*
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;* JAVA UTILITIES FOR 6502
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;*
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.INCLUDE "global.inc"
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.EXPORT UTIL_INIT,MEMSRC,MEMDST,MEMCPY,MEMCLR,MEMSET
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.EXPORT MUL5,MUL9,MUL10
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.SEGMENT "INIT"
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UTIL_INIT: LDA #<MEMSRC
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STA LINK_MEMSRC
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LDA #>MEMSRC
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STA LINK_MEMSRC+1
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LDA #<MEMDST
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STA LINK_MEMDST
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LDA #>MEMDST
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STA LINK_MEMDST+1
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LDA #<MEMCPY
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STA LINK_MEMCPY
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LDA #>MEMCPY
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STA LINK_MEMCPY+1
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LDA #<MEMCLR
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STA LINK_MEMCLR
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LDA #>MEMCLR
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STA LINK_MEMCLR+1
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LDA #<MEMSET
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STA LINK_MEMSET
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LDA #>MEMSET
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STA LINK_MEMSET+1
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RTS
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.CODE
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;*
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;* SET MEMORY SRC OPERAND
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;* ENTRY: AX = ADDRESS
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;*
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MEMSRC: STA SRCADDR
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STX SRCADDR+1
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RTS
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;*
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;* SET MEMORY DST OPERAND
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;* ENTRY: AX = ADDRESS
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;*
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MEMDST: STA DSTADDR
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STX DSTADDR+1
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RTS
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;*
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;* COPY MEMORY
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;*
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;* ENTRY: SRCADDR = SOURCE ADDRESS
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;* DSTADDR = DESTINATION ADDRESS
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;* AX = LENGTH IN BYTES
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;*
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MEMCPY: TAY
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LDA SRCADDR+1
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CMP DSTADDR+1
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BCC REVCPY
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BNE :+
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LDA SRCADDR
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CMP DSTADDR
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: BCS FORCPY
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REVCPY: TXA ; REVERSE DIRECTION COPY
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; CLC
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ADC SRCADDR+1
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STA SRCADDR+1
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TXA
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CLC
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ADC DSTADDR+1
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STA DSTADDR+1
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INX
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CPY #$00
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BEQ :++
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DEY
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BEQ :+
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REVCPYLOOP: LDA (SRCADDR),Y
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STA (DSTADDR),Y
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DEY
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BNE REVCPYLOOP
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: LDA (SRCADDR),Y ; DO ONE MORE COPY, Y = #$00
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STA (DSTADDR),Y ; (THIS MAKES FOR A SLIGHTLY FASTER INNER LOOP)
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: DEY ; NOW Y = #$FF
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DEX
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BEQ :+
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DEC SRCADDR+1
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DEC DSTADDR+1
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BNE REVCPYLOOP
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: RTS
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FORCPY: TYA ; FORWARD DIRECTION COPY
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EOR #$FF
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TAY
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INY
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BNE :+
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DEX
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: LDA SRCADDR
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STY SRCADDR
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; SEC
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SBC SRCADDR
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STA SRCADDR
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LDA SRCADDR+1
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SBC #$00
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STA SRCADDR+1
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LDA DSTADDR
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STY DSTADDR
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SEC
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SBC DSTADDR
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STA DSTADDR
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LDA DSTADDR+1
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SBC #$00
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STA DSTADDR+1
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INX
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FORCPYLOOP: LDA (SRCADDR),Y
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STA (DSTADDR),Y
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INY
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BNE FORCPYLOOP
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DEX
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BEQ :+
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INC SRCADDR+1
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INC DSTADDR+1
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BNE FORCPYLOOP
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: RTS
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;*
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;* CLEAR MEMORY
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;*
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;* ENTRY: DSTADDR = DESTINATION ADDRESS TO CLEAR
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;* AX = LENGTH IN BYTES
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;*
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MEMCLR: LDY #$00
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;*
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;* SET MEMORY
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;*
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;* ENTRY: DSTADDR = DESTINATION ADDRESS TO SET
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;* AX = LENGTH IN BYTES
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;* Y = VALUE TO SET
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;*
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MEMSET: STY TMP
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CPX #$00
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BEQ SMALLSET
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STA TMP+1
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LDY #$00
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LDA TMP
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: STA (DSTADDR),Y
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INY
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BNE :-
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INC DSTADDR+1
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DEX
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BNE :-
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LDA TMP+1
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SMALLSET: TAY
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BEQ SETDONE
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LDA TMP
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: DEY
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STA (DSTADDR),Y
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BNE :-
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SETDONE: RTS
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;*
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;* MULTIPLY BY 5 - TURN INDEX INTO CONSTANT POOL INTO OFFSET
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;* ENTRY: AX = VALUE
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;* EXIT: AX = VALUE * 5
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;* C = OVERFLOW
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;*
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MUL5: STA TMP
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STX TMP+1
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ASL
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ROL TMP+1
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ASL
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ROL TMP+1
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ADC TMP
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PHA
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TXA
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ADC TMP+1
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TAX
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PLA
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RTS
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;*
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;* MULTIPLY BY 7 - TURN INDEX INTO FIELD TABLE INTO OFFSET
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;* ENTRY: AX = VALUE
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;* EXIT: AX = VALUE * 7
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;* C = OVERFLOW
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;*
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;MUL7: STA TMP
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; STX TMP+1
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; ASL TMP
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; ROL TMP+1
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; ADC TMP
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; PHA
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; TXA
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; ADC TMP+1
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; TAX
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; PLA
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; ASL TMP
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; ROL TMP+1
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; ADC TMP
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; PHA
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; TXA
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; ADC TMP+1
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; TAX
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; PLA
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; RTS
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;*
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;* MULTIPLY BY 9 - TURN INDEX INTO FIELD TABLE INTO OFFSET
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;* ENTRY: AX = VALUE
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;* EXIT: AX = VALUE * 9
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;* C = OVERFLOW
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;*
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MUL9: STA TMP
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STX TMP+1
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ASL
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ROL TMP+1
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ASL
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ROL TMP+1
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ASL
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ROL TMP+1
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ADC TMP
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PHA
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TXA
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ADC TMP+1
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TAX
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PLA
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RTS
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;*
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;* MULTIPLY BY 10 - TURN INDEX INTO METHOD TABLE INTO OFFSET
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;* ENTRY: AX = VALUE
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;* EXIT: AX = VALUE * 10
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;* C = OVERFLOW
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;*
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MUL10: STA TMP ; Y = X + 4X = 5X
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STX TMP+1
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ASL
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ROL TMP+1
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ASL
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ROL TMP+1
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ADC TMP
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STA TMP
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TXA
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ADC TMP+1
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ASL TMP ; RETURN Y * 4 = 5X * 2 = 10X
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ROL
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TAX
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LDA TMP
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RTS
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;*
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;* MULTIPLY BY 20 - TURN INDEX INTO METHOD TABLE INTO OFFSET
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;* ENTRY: AX = VALUE
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;* EXIT: AX = VALUE * 20
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;* C = OVERFLOW
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;*
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;MUL20: STA TMP ; Y = X + 4X = 5X
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; STX TMP+1
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; ASL
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; ROL TMP+1
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; ASL
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; ROL TMP+1
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; ADC TMP
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; STA TMP
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; TXA
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; ADC TMP+1
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; ASL TMP ; RETURN Y * 4 = 5X * 4 = 20X
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; ROL
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; ASL TMP
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; ROL
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; TAX
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; LDA TMP
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; RTS
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