mirror of
https://github.com/nathanriggs/AppleIIAsm-Collection.git
synced 2024-11-30 15:49:55 +00:00
c8cac53c5e
Massive updates that changes the way most subroutines are handled. Major bugfixes, various utilities added, started higher-level libraries.
100 lines
2.2 KiB
Plaintext
100 lines
2.2 KiB
Plaintext
*``````````````````````````````*
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* HEXASC2HEX *
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* *
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*- -*
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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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*- -*
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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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*- -*
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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 = COUNTER; TRASH *
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* .X = COUNTER; TRASH *
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* .A = LOW BYTE OF RET ADDR *
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* *
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* [RETURN] = STRING VALUE *
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* [RETLEN] = LENGTH OF STRING *
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*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
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*
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HEXASC2HEX
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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 ADDR1
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PLA
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STA ADDR1+1
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*
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LDY #1
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LDA (ADDR1),Y
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STA :HI
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INY
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LDA (ADDR1),Y
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STA :LO
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*
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SEC
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SBC #'0'
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CMP #10 ; ASCII OFFSET
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BCC :CONT
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SBC #7 ; SUBTRACT LETTER OFFSET
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:CONT
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STA :LO
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LDA :HI
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SEC
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SBC #'0'
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CMP #10 ; IS NUMBER?
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BCC :C2 ; THEN DONE
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SBC #7 ; OTHERWISE LETTER OFFSET
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:C2
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STA :HI
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ASL
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ASL
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ASL
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ASL
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ORA :LO
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*
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STA RETURN
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LDY #1
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STY RETLEN
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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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RTS ; RETURN
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*
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** DATA
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*
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:HI DS 1
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:LO DS 1
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*
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