mirror of
https://github.com/nathanriggs/AppleIIAsm-Collection.git
synced 2024-12-03 18:49:28 +00:00
196 lines
4.5 KiB
Plaintext
196 lines
4.5 KiB
Plaintext
*
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*``````````````````````````````*
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* ADIM81D : INIT 1D ARRAY *
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*- -*
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* CREATES AN ARRAY OF LENGTH *
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* [:ASIZE] WITH ELEMENTS OF *
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* LENGTH [:ESIZE] AT MEMORY *
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* LOCATION POINTED TO BY *
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* [:ALOC]. RETURNS ARRAY START *
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* LOCATION IN .A *
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*- -*
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* FIRST BYTE OF MEMORY USED *
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* HOLDS LENGTH OF ARRAY; *
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* SECOND BYTE HOLDS LENGTH OF *
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* ELEMENTS. *
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*- -*
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* CLOBBERS: *
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* *
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* FLAGS: ????---- REG: AXYM *
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*- -*
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* CYCLES: ??? *
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* SIZE: *
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*- -*
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* USAGE: *
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* *
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* LDA #>$300 ; ARRAYLOC *
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* PHA *
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* LDA #<$300 *
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* PHA *
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* LDA #10 ; ARRAY SIZE *
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* PHA *
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* LDA #2 ; ELEMENT SIZE *
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* PHA *
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* JSR DIM81 *
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*- -*
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* ENTRY *
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* *
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* TOP OF STACK *
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* *
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* LOW BYTE OF RETURN ADDRESS *
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* HI BYTE OF RETURN ADDRESS *
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* ELEMENT SIZE *
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* ARRAY SIZE *
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* LOW BYTE OF ARRAY ADDRESS *
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* HIGH BYTE OF ARRAY ADDRESS *
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*- -*
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* EXIT *
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* *
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* TOP OF STACK *
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* *
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* LOW BYTE OF RETURN ADDRESS *
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* HI BYTE OF RETURN ADDRESS *
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* *
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* .Y = LO BYTE OF ARRAY ADDR *
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* .X = HI BYTE OF ARRAY ADDR *
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* .A = ARRAY SIZE *
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* *
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* [RETURN] = TOTAL SIZE OF *
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* ARRAY IN BYTES (WORD) *
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*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
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*
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ADIM81
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*
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** FIRST, CLEAR BLOCK OF MEM TO BE USED
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** THEN MUL [:ASIZE] BY [:ESIZE], AND ADD 2 TO
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** GET TOTAL MEMORY USED BY ARRAY
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*
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** SAVE RETURN ADDRESS
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*
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PLA
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STA RETADR
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PLA
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STA RETADR+1
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*
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** GET PARAMETERS
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*
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PLA
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STA :ESIZE ; ELEMENT SIZE
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STA :ESZBAK
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PLA
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STA :ASIZE ; ARRAY SIZE
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STA :ASZBAK
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PLA
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STA ADDR1
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PLA
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STA ADDR1+1
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LDY #0
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LDA #0
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STY SCRATCH
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BEQ :ENTLP
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*
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** MULTIPLY [:ASIZE] AND [:ESIZE] TO GET
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** TOTAL SIZE OF MEMORY TO CLEAR AND USE
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*
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:DOADD
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CLC
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ADC :ASIZE
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TAX
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*
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TYA
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ADC SCRATCH
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TAY
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TXA
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*
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:LP
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ASL :ASIZE
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ROL SCRATCH
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:ENTLP
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LSR :ESIZE
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BCS :DOADD
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BNE :LP
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*
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CLC
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INX
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INX ; INCREASE BY TWO
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; TO MAKE ROOM FOR SIZES
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BCC :NOINY ; IF .X ROLLS OVER, INC .Y
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INY
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:NOINY
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STX :MSIZE ; LOW BYTE
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STY :MSIZE+1 ; HIGH BYTE
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*
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** NOW CLEAR MEMORY BLOCKS
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*
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** FILL WHOLE PAGES FIRST
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*
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LDA #0 ; FILL VALUE
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LDX :MSIZE+1
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BEQ :PART ; IF NO WHOLE PAGES, JUST PART
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LDY #0
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:FULL
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STA (ADDR1),Y
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INY ; NEXT BYTE
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BNE :FULL ; LOOP UNTIL PAGE DONE
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INC ADDR1+1 ; GO TO NEXT PAGE
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DEX
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BNE :FULL ; LOOP IF PAGES LEFT
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*
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** NOW DO REMAINING PARTIAL PAGES
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*
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:PART
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LDX :MSIZE ; PARTIAL PAGE BYTES
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BEQ :MFEXIT ; EXIT IF = 0
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LDY #0
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:PARTLP
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STA (ADDR1),Y ; STORE VAL
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INY ; INC INDEX
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DEX ; DEC COUNTER
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BNE :PARTLP ; LOOP UNTIL DONE
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:MFEXIT
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*
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** MEMORY FILL IS DONE
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*
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** THEN, SET SIZES
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*
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LDY #0
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LDA :ASZBAK
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STA (ADDR1),Y
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INY
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LDA :ESZBAK
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STA (ADDR1),Y
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*
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** RESTORE RETURN ADDRESS
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*
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LDA RETADR+1
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PHA
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LDA RETADR
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PHA
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*
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** RETURN POINTER TO STARTING ADDR OF ARRAY
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*
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LDY ADDR1 ; LOW
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LDX ADDR1+1 ; HIGH
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LDA :ASZBAK
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*
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** STORE TOTAL ARRAY SIZE IN BYTES
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** IN MEMORY ALLOCATED FOR RETURN VALUES
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*
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LDA :MSIZE
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STA RETURN
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LDA :MSIZE+1
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STA RETURN+1
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LDA #2
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STA RETLEN ; 2 BYTE LENGTH
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*
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RTS
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*
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** DATA
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*
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:MSIZE DS 2
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:ASIZE DS 1
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:ESIZE DS 1
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:ASZBAK DS 1
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:ESZBAK DS 1
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*
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