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55 lines
2.0 KiB
Plaintext
55 lines
2.0 KiB
Plaintext
; C02 library stdio.h02 assembly language subroutines
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; Requires external routines GETKEY, prchr, delchr, and NEWLIN
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; external zero page locations SRCLO and SRCHI
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; and external constants DELKEY, ESCKEY, and RTNKEY
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;char getchr()
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GETCHR EQU GETKEY ;Alias to external GETKEY routine
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;void putchr(c)
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PUTCHR EQU PRCHR ;Alias to external PRCHR Routine
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;char getstr(&s)
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GETSTR: JSR SETSRC ;Initialize Source String
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GETSTL: JSR GETCHR ;Get Keypress
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GETSTD: CMP #DELKEY ;If Delete
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BNE GETSTE ;Then
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TYA ; If Offset is Zero
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BEQ GETSTL ; Get Next Character
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DEY ; Else Decrement Offset
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JSR DELCHR ; Delete Previous Character
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JMP GETSTL ; and Get Next Character
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GETSTE: CMP #ESCKEY ;Else If Escape
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BNE GETSTC ;Then
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LDY #$FF ; Return -1
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BNE GETSTY
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GETSTC: CMP #RTNKEY ;Else If Not Carriage Return
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BEQ GETSTX
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JSR PUTCHR ; Echo Character
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STA (SRCLO),Y ; Store Character at offset
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INY ; increment offset and
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BPL GETSTL ; loop if less than 128
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GETSTX: JSR NEWLIN ;Else Advance Cursor to Next Line
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LDA #$00 ; Terminate String
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STA (SRCLO),Y ; and
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GETSTY: TYA ; Return String Length
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RTS
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;char outstr(n, &s)
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OUTSTR: LDA #$00 ;Set Start Position to 0
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;and fall into outsub
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;char outsub(n, &s)
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OUTSUB: JSR SETSRC ;Initialize Source String
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TAY ;Initialize character offset
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OUTSUL: LDA (SRCLO),Y ;Read next character in string
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BEQ OUTSUX ;If Not 0
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JSR PUTCHR ; Print character at offset,
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INY ; increment offset, and
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BPL OUTSUL ; loop if less than 128
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OUTSUX: TAY ;Return number of
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RTS ; characters printed
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;char putstr(*s)
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PUTSTR: JSR OUTSTR ;Write string to screen
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JMP NEWLIN ;Call external NEWLINe routine and return
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