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206 lines
8.2 KiB
Plaintext
206 lines
8.2 KiB
Plaintext
; C02 library string.h02 assembly language subroutines
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; Requires external routines SETSRC, SETDSB, and SETDST
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; Requires the following RAM locations be defined
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; external zero page words SRCPTR and DSTPTR, bytes
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; TEMP0 and TEMP3, and block SYSBFR.
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SUBROUTINE STRING
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;strcmp(&s) - Compare String (to Destination String)
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;Requires: DSTPTR - Pointer to destination string
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;Args: X,Y = Pointer to source string
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;Sets: SRCPTR = Pointer to string
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; N based on return value of A
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;Returns A=$01 and C=1 if Destination > Source
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; A=$00 and Z=1, C=1 if Destination = Source
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; A=$FF and C=0 if Destination < Source
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; Y=Position of first character that differs
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STRCMP: JSR SETSRC ;Initialize Source String
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STRCML LDA (DSTPTR),Y ;Load Destination Character
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CMP (SRCPTR),Y ;Compare Against Source Character
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BNE .CMPEND ;If Equal
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ORA (SRCPTR),Y ; OR with Source Character
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BEQ .RETURN ; If Both are 0, Return 0
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INY ; Increment Offset
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BPL STRCML ; and Loop if < 128
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.CMPEND BCC .RETFLS ;If Source < Destination, Return $FF & Carry Clear
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LDA #$01 ;Else Return 1 and Carry Set
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.RETURN RTS
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;strcnt(a,&s) - Count Occurrences of c in s
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;Args: A - Character to count
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; X,Y - Pointer to string
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;Sets: SRCPTR = Pointer to source string
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; N,Z based on return value of A
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;Returns: A,X = Number of occurrences
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; Y = Length of string
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STRCNT: STA TEMP0 ;Save Character
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JSR SETSRC ;Setup Source Pointer
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LDX #0 ;Initialize Character Count
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.CNTLOP LDA (SRCPTR),Y ;Get Next Character
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BEQ .CDONE ;If <> NUL
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CMP TEMP0 ;
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BNE .CNTSKP ; If Character Match
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INX ; Inrement Count
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.CNTSKP INY ; Increment Index
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BPL .CNTLOP ; and Loop if < 128
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.CDONE TXA ;ReturnCount
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RTS ;and Return
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;strchr(c, &s) - Find First Occurance of Character in String
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;Args: A = Character to look for
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; X,Y = Pointer to string to search in
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;Sets: SRCPTR = Pointer to string
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; TEMP3 = Character being searched for
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; N,Z based on return value of A
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;Returns: A = Position in string, C=1 if found
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; A = $FF, C=0 if not found
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; Y = Position of last character scanned
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STRCHR: JSR SETSRC ;Initialize Source String
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STRCHA: STA TEMP3 ;Save Search Character (alternate entry point)
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.CHRLOP LDA (SRCPTR),Y ;Get Next Character
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BEQ .CLCFLS ;If NUL, Return $FF and Carry Clear
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CMP TEMP3 ;Compare Character
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BEQ .LENFIN ;If Found, Return Index
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INY ;Increment Counter and Loop if < 128
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BPL .CHRLOP ;Else Return $FF and Carry Clear
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.CLCFLS CLC ;Clear Carry
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.RETFLS LDA #$FF ;Load -1 into Accumulater
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BNE .RETURN ;and Return
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;strlen(&s) - Return Length of String
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;Args: X,Y - Pointer to string
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;Sets: SRCPTR = Pointer to source string
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; N,Z based on return value of A
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;Returns: A,Y = Length of string
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STRLEN: JSR SETSRC ;Initialize Source String
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STRLEA: LDA (SRCPTR),Y ;Get Next Character
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BEQ .LENFIN ;If <> NUL
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INY ; Increment Index
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BPL STRLEA ; and Loop if < 128
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.LENFIN TYA ;Transfer Index to Accumulator
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RTS ;and Return
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;strcpb(&s) - Copy String to System Buffer
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;Args: X,Y = Pointer to source string
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;Sets: SRCPTR = Pointer to source string
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; DSTPTR = Address of System Buffer
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; N,Z based on return value of A
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;Returns: A,Y = Length of copied string
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STRCPB: JSR SETSRC ;Set Source Pointer to String Address
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JSR SETDSB ;Set Destination Pointer to System Buffer
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BVC STRCPA ;Execute String Copy
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;strcat(&s) Concatenate String (to Destination String)
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;Requires: DSTPTR - Pointer to destination string
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;Args: X,Y = Pointer to source string
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;Sets: SRCPTR = Pointer to source string
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; TEMP3 = Length of source prior to concatenation
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; N,Z based on return value of A
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;Affects: C
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;Returns: A,Y = Total length of concatenated string
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STRCAT: JSR SETSRC ;Initialize Source String
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.CATLOP LDA (DSTPTR),Y ;Find end of Destination String
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BEQ .CATFIN ;
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INY ;
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BPL .CATLOP ;
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.CATFIN STY TEMP3 ;Subtract Destination String Length
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LDA SRCPTR ; from Source String Pointer
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SEC
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SBC TEMP3
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STA SRCPTR
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LDA SRCPTR+1
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SBC #$00
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STA SRCPTR+1
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JMP .CPYLOP ;Execute String Copy
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;strcpy(&s) - Copy String (to Destination String)
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;Requires: DSTPTR - Pointer to destination string
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;Args: X,Y = Pointer to source string
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;Sets: SRCPTR = Pointer to source string
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; N,Z based on return value of A
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;Returns: A,Y = Number of characters copied
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STRCPA: LDY #0 ;Alternate entry point
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BEQ .CPYLOP ;for when Source already set
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STRCPY: JSR SETSRC ;Initialize Source String
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.CPYLOP LDA (SRCPTR),Y ;Get Character from Source String
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STA (DSTPTR),Y ;Copy to Destination String
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BEQ .CPYFIN ;If <> NUL
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INY ; Increment Index
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BPL .CPYLOP ; and Loop if < 128
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.CPYFIN TYA ;Transfer Index to Accumulator
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RTS ;and Return
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;strcut(n, &s) - Copy from Position n to End of Source
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;Requires: DSTPTR - Pointer to destination string
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;Args: A = Starting position in start string
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; X,Y = Pointer to source string
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;Sets: SRCPTR = Pointer to specified position in source string
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; N,Z based on return value of A
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;Returns: A,Y = Length of copied string
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STRCUT: JSR SETSRC ;Initialize Source String
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CLC
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ADC SRCPTR ;Move Source Pointer
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STA SRCPTR ; to Specified Position in String
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BCC .CPYLOP
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INC SRCPTR+1
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JMP .CPYLOP ;and Jump Into String Copy Loop
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;strstr(&s) - Search for String (in Destination String)
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;Requires: DSTPTR - Pointer to destination string
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;Args: X,Y = Pointer to search string
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;Sets: DSTPTR = Pointer to position in source string
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; End of string if not found
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; SRCPTR = Pointer to source string
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; TEMP3 = Last position checked in destination string
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; N,Z based on return value of A
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;Returns: A = Position, C=1 if found
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; A = $FF, C=0 if not found
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; Y = Last position checked in source string
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STRSTR: JSR SETSRC ;Initialize Source String
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STY TEMP3 ;Initialize Position
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.STRLOP LDY #$00; ;Initialize Compare Offset
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LDA (DSTPTR),Y ;Get Start Character in Destination
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BEQ .CLCFLS ;If NUL return $FF and Carry Clear
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JSR STRCML ;Jump into Compare Loop
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BEQ .STRFIN ;If Not Equal
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BMI .STRNXT ; If Source is Greater
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LDA (SRCPTR),Y ; If at End of Source String
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BEQ .STRFIN ; Return Current Position
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.STRNXT INC TEMP3 ; Else Increment Position
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BMI .CLCFLS ; If > 127 return $FF and Carry Clear
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INC DSTPTR ; Increment Source Pointer
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BNE .STRLOP
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INC DSTPTR+1 ; If not End of Memory
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BNE .STRLOP ; Loop
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BEQ .CLCFLS ; Else return $FF and Carry Clear
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.STRFIN SEC ;Else Set Carry
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LDA TEMP3 ; Load Position
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RTS ; and Return
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;strrch(c, &s) - Find Last Occurrence of Character in String
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;Args: A = Character to look for
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; X,Y = Pointer to string to search in
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;Sets: SRCPTR = Pointer to string
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; TEMP3 = Character being searched for
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; N,Z based on return value of A
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;Affects: Y,C
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;Returns: A,X = Position of last occurrence in string
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; $FF if not found
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; Y = Length of String
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STRRCH: JSR SETSRC ;Initialize Source String
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STA TEMP3 ;Save Search Character (alternate entry point)
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LDX #$FF ;Initialize Position
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.RCHLOP LDA (SRCPTR),Y ;Get Next Character
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BEQ .RCHFIN ;If NUL, Exit with Position
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CMP TEMP3 ;Compare Character
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BNE .RCHNXT ;If Found
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TYA ; Store Counter
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TAX
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.RCHNXT INY ;Increment Counter
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BPL .RCHLOP ; and Loop if < 128
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.RCHFIN TXA ;Copy Position to Accumulater
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RTS ; and Return
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ENDSUBROUTINE
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