mirror of https://github.com/RevCurtisP/C02.git
115 lines
3.9 KiB
Plaintext
115 lines
3.9 KiB
Plaintext
; C02 module stringm.h02 assembly language subroutines
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; Requires external routines SETSRC, TOLOWR, and TOUPPR
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; Requires the following RAM locations be defined
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; external zero page word SRCPTR
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; and external bytes TEMP0 and TEMP1
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SUBROUTINE STRINGM
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;straps(c, s) - Append space to string s
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;Args: A = Character to be appended
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; X,Y = Pointer to string
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;Affects N,Z
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;Returns A,Y = New String Length
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STRAPS: LDA ' ' ;Set Append Character to Space
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;strapd(c, s) - Append character c to string s
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;Args: A = Character to be appended
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; X,Y = Pointer to string
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;Affects N,Z
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;Returns A,Y = New String Length
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STRAPD: STA TEMP0 ;Save Character to Append
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JSR STRLEN ;Get Length of String
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BMI .ERROR ;Return 255 if > 127
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LDA TEMP0 ;Restore Character to Append
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.APDLOP STA (SRCPTR),Y ;Store at End of String
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BEQ .RETLEN ;Exit if NUL
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INY ;Increment Past New Character
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LDA #0 ;Terminate String
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STA (SRCPTR),Y
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BEQ .RETLEN ;and Append to String
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;strpps(c, s) - Prepend space to string s
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;Args: A = Character to be appended
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; X,Y = Pointer to string
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;Affects N,Z
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;Returns A,Y = New String Length
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STRPPS: LDA ' ' ;Set Append Character to Space
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;strppd(c, s) - Prepend Character to String
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;Args: A = Character to be appended
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; X,Y = Pointer to string
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;Sets: N,Z
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;Returns A = New String Length
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STRPPD: STA TEMP0 ;Save Character to Append
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JSR STRLEN ;Get Length of String
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BMI .ERROR ;Return 255 if > 127
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INY ;Bump up string length
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TYA ;Push string length onto stack
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PHA
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.PPDLOP DEY ;Copy Preceding Character
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LDA (SRCPTR),Y
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INY ;into Current Position
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STA (SRCPTR),Y
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DEY ;Move to Preceding Position
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BNE .PPDLOP ;and Loop
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LDA TEMP0 ;Retrieve Character
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STA (SRCPTR),Y ;and Store in Position 0
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PLA ;Retrieve new string length
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RTS
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.ERROR LDA #$FF ;Return Error Code FALSE
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RTS
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;STRPAD(n, &s) - Pad or Truncate String
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;Args: A - New Length of String
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; X,Y - Pointer to string
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;Sets: SRCPTR = Pointer to source string
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;Returns: A,Y = Length of string
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; N,Z based on A
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STRPAD: STA TEMP0 ;Save New Length
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JSR STRLEN ;Get Current Length of String
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CMP TEMP0
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BCS .PDONE ;If Shorter than New Length
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LDA #' '
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.PLOOP STA (SRCPTR),Y ; Fill with Spaces
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INY
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BMI .PDONE ; Until 128 or
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CPY TEMP0 ; New Length is Reached
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BNE .PLOOP
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.PDONE LDA #0 ;Terminate String
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STA (SRCPTR),Y
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TYA ;and Return Length
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RTS
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;STRLWR(&s) - Convert String to Lower Case
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;Args: X,Y - Pointer to string
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;Sets: SRCPTR = Pointer to source string
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;Returns: A,Y = Length of string
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; N,Z based on A
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STRLWR: JSR SETSRC ;Initialize Source String
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.LLOOP LDA (SRCPTR),Y ;Get Next Character
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BEQ .RETLEN ;If <> NUL
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JSR TOLOWR ; Convert to Lower Case
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STA (SRCPTR),Y ; and Replace in String
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INY ; Increment Index
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BPL .LLOOP ; and Loop if < 128
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TYA ;Transfer Index to Accumulator
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RTS ;and Return
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;STRUPR(&s) - Convert String to Lower Case
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;Args: X,Y - Pointer to string
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;Sets: SRCPTR = Pointer to source string
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;Returns: A,Y = Length of string
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; N,Z based on A
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STRUPR: JSR SETSRC ;Initialize Source String
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.ULOOP LDA (SRCPTR),Y ;Get Next Character
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BEQ .RETLEN ;If <> NUL
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JSR TOUPPR ; Convert to Lower Case
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STA (SRCPTR),Y ; and Replace in String
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INY ; Increment Index
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BPL .ULOOP ; and Loop if < 128
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.RETLEN TYA ;Transfer Index to Accumulator
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RTS ;and Return
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ENDSUBROUTINE
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