mirror of
https://github.com/nathanriggs/AppleIIAsm-Collection.git
synced 2024-06-02 06:41:34 +00:00
163 lines
5.5 KiB
NASM
163 lines
5.5 KiB
NASM
*
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*``````````````````````````````*
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* HRSTR *
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* *
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* PRINT A STRING OF CHARACTERS *
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* TO THE CURRENT WORKING PAGE *
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* OF THE HIRES SCREEN. *
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* *
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* INPUT: *
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* *
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* ZPW1 = X POSITION (2) *
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* ZPB1 = Y POSITION (1) *
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* ZPW4 = STRING ADDRESS (2) *
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* ZPB2 = CHARSET OFFSET (1) *
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* *
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* DESTROYS: NZCIDV *
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* ^^^ ^ *
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* *
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* CYCLES: 715+ *
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* SIZE: 639 BYTES *
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*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
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*
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]STRX EQU ZPW1 ; {0C2B} X POSITION (0..39)
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]STRY EQU ZPB1 ; {0C2B} Y POSITION (0..191)
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]STR EQU ZPW2 ; {0C2B} STRING ADDRESS
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]TBL HEX 0000 ; {0C2B} CHAR TABLE ADDRESS
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]ADDR EQU ZPW4 ; {0C2B} CHARACTER ADDRESS
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]CHAR HEX 0000 ; {0C2B} CHARACTGER OFFSET
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]PRNBYTE HEX 0000 ; {0C2B} BYTE TO PLOT TO SCREEN
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]STROFF EQU ZPB2 ; {0C1B} STRING OFFSET
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]LEN HEX 0000 ; {0C1B} STRING LENGTH
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]XCOUNT HEX 0000 ; {0C1B} STRING COUNTER
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]BCOUNT HEX 0000 ; {0C1B} BYTE COUNTER
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]YSUM HEX 0000 ; {0C1B} Y POSITION SUM
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*
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HRSTR
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*
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LDA #0 ; {3C2B}
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STA ]LEN ; {4C3B}
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STA ]XCOUNT ; {4C3B}
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STA ]BCOUNT ; {4C3B}
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*
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LDY #0 ; {3C2B}
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LDA (]STR),Y ; {5C3B}
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STA ]LEN ; {4C3B}
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*
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:LOOP
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LDA ]LEN ; {4C3B} IF LEN = XCOUNT, EXIT
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CMP ]XCOUNT ; {4C3B}
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BEQ :EXIT ; {3C2B}
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JMP :CONT ; {3C3B}
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:EXIT JMP :HRSTREXIT ; {3C3B}
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:CONT
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INC ]XCOUNT ; {5C3B} INCREMENT STRING CHAR POS
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LDY ]XCOUNT ; {4C3B}
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LDA (]STR),Y ; {5C3B} GET NEXT CHAR IN STRING
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SEC ; {2C1B}
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SBC ]STROFF ; {4C3B} SUBTRACT OFFSET, NORMALLY #$A0
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STA ]CHAR ; {4C3B} STORE CHARACTER OFFSET
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LDA #0 ; {3C2B}
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STA ]CHAR+1 ; {4C3B}
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*
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ASL ]CHAR ; {6C3B} MULTIPLY CHAR OFFSET BY 8
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ROL ]CHAR+1 ; {6C3B} TO GET OFFSET IN BYTES
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ASL ]CHAR ; {6C3B}
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ROL ]CHAR+1 ; {6C3B}
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ASL ]CHAR ; {6C3B}
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ROL ]CHAR+1 ; {6C3B}
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*
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LDA ]CHAR ; {4C3B} ADD TABLE ADDRESS TO
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CLC ; {2C1B} CHAR OFFSET AND STORE AS
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ADC #<HRCTBL ; {4C3B} NEW ADDRESS. THIS IS THE
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STA ]ADDR ; {4C3B} ADDRESS OF THE INDIVIDUAL
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LDA ]CHAR+1 ; {4C3B} CHARACTER IN THE TABLE
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ADC #>HRCTBL ; {4C3B}
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STA ]ADDR+1 ; {4C3B}
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*
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LDY #0 ; {3C2B} RESET BYTE COUNTER
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STY ]BCOUNT ; {4C3B}
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LDA (]ADDR),Y ; {5C3B} LOAD BYTE TO PLOT
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STA ]PRNBYTE ; {4C3B}
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LDA ]BCOUNT ; {4C3B}
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CLC ; {2C1B} NOW GET Y POS OFFSET
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ADC ]STRY ; {4C3B}
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STA ]YSUM ; {4C3B}
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HBSET ]STRX;]YSUM;]PRNBYTE ; {54C37B} PLOT BYTE
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*
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INC ]BCOUNT ; {5C3B} INCREMENT BYTE COUNTER
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LDY ]BCOUNT ; {4C3B}
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LDA (]ADDR),Y ; {5C3B} LOAD BYTE TO PRINT
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STA ]PRNBYTE ; {4C3B}
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TYA ; {2C1B} NOW GET Y OFFSET
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CLC ; {2C1B}
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ADC ]STRY ; {4C3B}
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STA ]YSUM ; {4C3B}
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HBSET ]STRX;]YSUM;]PRNBYTE ; {54C37B} PLOT CHARACTER
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*
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INC ]BCOUNT ; {5C3B}
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LDY ]BCOUNT ; {4C3B}
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LDA (]ADDR),Y ; {5C3B}
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STA ]PRNBYTE ; {4C3B}
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TYA ; {2C1B}
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CLC ; {2C1B}
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ADC ]STRY ; {4C3B}
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STA ]YSUM ; {4C3B}
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HBSET ]STRX;]YSUM;]PRNBYTE ; {54C37B}
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*
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INC ]BCOUNT ; {5C3B}
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LDY ]BCOUNT ; {4C3B}
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LDA (]ADDR),Y ; {5C3B}
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STA ]PRNBYTE ; {4C3B}
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TYA ; {2C1B}
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CLC ; {2C1B}
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ADC ]STRY ; {4C3B}
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STA ]YSUM ; {4C3B}
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HBSET ]STRX;]YSUM;]PRNBYTE ; {54C37B}
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*
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INC ]BCOUNT ; {5C3B}
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LDY ]BCOUNT ; {4C3B}
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LDA (]ADDR),Y ; {5C3B}
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STA ]PRNBYTE ; {4C3B}
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TYA ; {2C1B}
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CLC ; {2C1B}
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ADC ]STRY ; {4C3B}
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STA ]YSUM ; {4C3B}
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HBSET ]STRX;]YSUM;]PRNBYTE ; {54C37B}
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*
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INC ]BCOUNT ; {5C3B}
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LDY ]BCOUNT ; {4C3B}
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LDA (]ADDR),Y ; {5C3B}
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STA ]PRNBYTE ; {4C3B}
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TYA ; {2C1B}
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CLC ; {2C1B}
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ADC ]STRY ; {4C3B}
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STA ]YSUM ; {4C3B}
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HBSET ]STRX;]YSUM;]PRNBYTE ; {54C37B}
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*
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INC ]BCOUNT ; {5C3B}
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LDY ]BCOUNT ; {4C3B}
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LDA (]ADDR),Y ; {5C3B}
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STA ]PRNBYTE ; {4C3B}
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TYA ; {2C1B}
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CLC ; {2C1B}
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ADC ]STRY ; {4C3B}
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STA ]YSUM ; {4C3B}
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HBSET ]STRX;]YSUM;]PRNBYTE ; {54C37B}
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*
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INC ]BCOUNT ; {5C3B}
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LDY ]BCOUNT ; {4C3B}
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LDA (]ADDR),Y ; {5C3B}
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STA ]PRNBYTE ; {4C3B}
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TYA ; {2C1B}
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CLC ; {2C1B}
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ADC ]STRY ; {4C3B}
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STA ]YSUM ; {4C3B}
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HBSET ]STRX;]YSUM;]PRNBYTE ; {54C37B}
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*
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INC ]STRX ; {5C3B}
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JMP :LOOP ; {3C3B}
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*
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:HRSTREXIT
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RTS ; {6C1B}
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