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124 lines
4.7 KiB
Plaintext
124 lines
4.7 KiB
Plaintext
; C02 library memory.h02 assembly language subroutines
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; Requires external routines SETSRC and SETDST
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; Requires the following RAM locations be defined
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; external zero page byte pairs SRCLO,SRCHI and DSTLO,DSTHI
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; and external bytes TEMP0 and TEMP1
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;memchr(c, n) - Find Character in Destination Array
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;Args: A = Character to look for
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; Y = Number of Elements to Search
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;Uses: DSTLO,DSTHI = Pointer to Destination Array
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;Sets: TEMP1 = Character being searched for
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; TEMP0 = Number of bytes
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;Affects: N,Z
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;Returns: A = Position in Array, 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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MEMCHR: STA TEMP1 ;Save Search Character
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STY TEMP0 ;Save Count
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BEQ MEMCLC ;If 0, Return Not Found
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LDY #$00 ;Initialize Index
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MEMCHL: LDA (DSTLO),Y ;Get Next Character
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CMP TEMP1 ;Compare Character
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BEQ MEMCLX ;If Found, Return Index
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INY ;Increment Counter
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CPY TEMP0 ;If < Count, Loop
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BCC MEMCHL ;Else
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MEMCLC: CLC ;Clear Carry
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LDA #$FF ;Load -1 into Accumulater
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RTS ;and Return
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MEMCLX: TYA ;Return Index into String
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RTS
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;memdst(&r) - Set Destination Array
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; Called before strcat(), memcmp(), memcpy(), strstr()
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;Args: X,Y = Pointer to destination Array
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;Sets: DSTLO,DSTHI = Pointer to destination Array
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;Affects: N,Z
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MEMDST EQU SETDST ;Aliased to System Header function
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;Set Source Address and Number of Characters
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;Args: X,Y = Pointer to Source Array
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;Sets: DSTLO,DSTHI = Pointer to destination Array
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; TEMP0 - Number of Characters
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;Affects: A,N,Z
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MEMSRC: JSR SETSRC ;Initialize Source Array and Index
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MEMSRA: STA TEMP0 ;Store Number Of Character
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ORA #0 ;If Number of Characters
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BNE MEMSRX ; Equals 0
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PLA ; Pull Return Address off Stack
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PLA ; Aborting Calling Routine
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MEMSRX: RTS ;Return
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;memcmp(n, &r) - Compare Array (to Destination Array)
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;Requires: DSTLO, DSTHI - Pointer to destination Array
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;Args: A = Number of Bytes to Compare
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; X,Y = Pointer to source Array
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;Sets: TEMP0 = Number of Bytes to Compare
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;Affects N
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;Returns A=$01 and C=1 if Destination > Source
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; A=$00 and Z=1 if Destination = Source
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; A=$FF and C=0 if Destination < Source
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; Y=Position of first character that differs
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MEMCMP: JSR MEMSRC ;Initialize Source, Index, and Count
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MEMCML: LDA (DSTLO),Y ;Load Destination Character
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CMP (SRCLO),Y ;Compare Against Source Character
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BNE MEMCMX ;If Equal
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INY ; Increment Offset
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CPY TEMP0 ; If < Count
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BCC MEMCML ; Loop
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MEMCMZ: LDA #$00 ; Else
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RTS ; Return 0
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MEMCMX: BCC MEMCLC ;If Source < Destination Return -1
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LDA #$01 ;Else Return 1
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MEMCMR: RTS ;
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;memcpy(n, &r) - Copy Array (to Destination Array)
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;Requires: DSTLO, DSTHI - Pointer to destination Array
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;Args: A = Number of bytes to copy
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; X,Y = Pointer to source Array
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;Sets: TEMP0 = Number of bytes to copy
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;Affects: A,Y,C,N,Z
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MEMCPY: JSR MEMSRC ;Initialize Source, Index, and Count
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MEMCPL: LDA (SRCLO),Y ;Get Character from Source Array
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STA (DSTLO),Y ;Copy to Destination Array
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INY ; Increment Index
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CPY TEMP0 ;If < Count
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BCC MEMCPL ; Loop
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RTS ;Else Return
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;memset(c, n) - Fill Destination Array
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;Args: A = Character to fill with
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; Y = Number of bytes to fill
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;Uses: DSTLO,DSTHI = Pointer to Destination Array
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;Sets: TEMP0 = Number of bytes
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;Affects: N,Z
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MEMSET: STY TEMP0 ;Save Count
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CPY #0 ;If 0
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BEQ MEMSEX ; Return
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LDY #$00 ;Initialize Index
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MEMSEL: STA (DSTLO),Y ;Store Character at Index
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INY ;Increment Counter
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CPY TEMP0 ;If < Count, Loop
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BCC MEMSEL ;Else
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MEMSEX: RTS
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;memswp(n, &r) - Swap Array (with Destination Array)
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;Requires: DSTLO, DSTHI - Pointer to destination Array
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;Args: A = Number of bytes to swap
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; X,Y = Pointer to source array
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;Sets: TEMP0 = Number of bytes to swap
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;Affects: A,X,Y,C,N,Z
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MEMSWP: JSR MEMSRC ;Initialize Source, Index, and Count
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MEMSWL: lDA (DSTLO),Y ;Get Character from Destination Array
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TAX ;Save in X Register
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LDA (SRCLO),Y ;Get Character from Source Array
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STA (DSTLO),Y ;Copy to Destination Array
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TXA ;Restore Saved Character
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STA (SRCLO),Y ;Copy to Source Array
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INY ; Increment Index
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CPY TEMP0 ;If < Count
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BCC MEMSWL ; Loop
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RTS ;Else Return
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