1
0
mirror of https://github.com/RevCurtisP/C02.git synced 2024-10-31 10:14:09 +00:00
C02/include/memory.a02
2018-01-28 13:30:49 -05:00

124 lines
4.7 KiB
Plaintext

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