mirror of
https://github.com/RevCurtisP/C02.git
synced 2024-11-28 10:51:14 +00:00
164 lines
6.3 KiB
NASM
164 lines
6.3 KiB
NASM
; C02 library string.h02 assembly language subroutines
|
|
; Requires the following RAM locations be defined
|
|
; zero page: strlo,strhi, and srclo,srchi
|
|
; anywhere: temp0 and temp0
|
|
|
|
;Internal Call - Initialize Source String
|
|
;Args: X,Y = Pointer to source string
|
|
;Sets: strlo,strhi = Pointer to source string
|
|
;Affects: N,Z
|
|
;Returns: Y = #$00
|
|
strini: STX strlo ;Save String Pointer
|
|
STY strhi
|
|
LDY #$00 ;Initialize Index Into String
|
|
RTS
|
|
|
|
;strcmp(&s) - Compare String (to Destination String)
|
|
;Requires: dstlo, dsthi - Pointer to destination string
|
|
;Args: X,Y = Pointer to source string
|
|
;Affects N,Z
|
|
;Returns A=$01 and C=1 if Destination > Source
|
|
; A=$00 and Z=1, C=1 if Destination = Source
|
|
; A=$FF and C=0 if Destination < Source
|
|
; Y=Position of first character that differs
|
|
strcmp: JSR strini ;Initialize Source String
|
|
strcml: LDA (dstlo),Y ;Load Destination Character
|
|
CMP (strlo),Y ;Compare Against Source Character
|
|
BNE strcmx; ;If Equal
|
|
ORA (strlo),Y ;OR with Source Character
|
|
BEQ strcmr ; If Both are 0, Return 0
|
|
INY ;Increment Offset
|
|
BPL strcml ; and Loop if < 128
|
|
strcmx: BCC strclx ;If Source < Destination
|
|
LDA #$01 ;Else Return 1
|
|
strcmr: RTS ;
|
|
|
|
;strchr(c, &s) - Find Character in String
|
|
;Args: A = Character to look for
|
|
; X,Y = Pointer to string to search in
|
|
;Sets: strlo,strhi = Pointer to string
|
|
; temp0 = Character being searched for
|
|
;Affects: N,Z
|
|
;Returns: A = Position in string, C=1 if found
|
|
; A = $FF, C=0 if not found
|
|
; Y = Position of last character scanned
|
|
strchr: JSR strini ;Initialize Source String
|
|
STA temp0; ;Save Character
|
|
chrstl: LDA (strlo),Y ;Get Next Character
|
|
BEQ strclc ;If NUL, Return $FF and Carry Clear
|
|
CMP temp0 ;Compare Character
|
|
BEQ strlex ;If Found, Return Index
|
|
INY ;Increment Counter
|
|
BPL chrstl ; and Loop if < 128
|
|
;Else Return $FF and Carry Clear
|
|
strclc: CLC ;Clear Carry
|
|
strclx: LDA #$FF ;Load -1 into Accumulater
|
|
RTS ;and Return
|
|
|
|
;strlen(&s) - Return Length of String
|
|
;Args: X,Y - Pointer to string
|
|
;Sets: strlo,strhi = Pointer to source string
|
|
;Affects: N,Z
|
|
;Returns: A,Y = Length of string
|
|
strlen: JSR strini ;Initialize Source String
|
|
strlel: LDA (strlo),Y ;Get Next Character
|
|
BEQ strlex ;If <> NUL
|
|
INY ; Increment Index
|
|
BPL strlel ; and Loop if < 128
|
|
strlex: TYA ;Transfer Index to Accumulator
|
|
RTS ;and Return
|
|
|
|
;strset(&s) - Set Destination String
|
|
; Called before strcat(), strcmp(), strcpy(), strstr()
|
|
;Args: X,Y = Pointer to destination string
|
|
;Sets: strlo,strhi = Pointer to destination string
|
|
;Affects: N,Z
|
|
strset: STX dstlo ;Save String Pointer
|
|
STY dsthi
|
|
RTS
|
|
|
|
;strcat(&s) Concatenate String (to Destination String)
|
|
;Requires: dstlo, dsthi - Pointer to destination string
|
|
;Args: X,Y = Pointer to source string
|
|
;Sets: strlo,strhi = Pointer to source string
|
|
; temp0 = Length of source prior to concatenation
|
|
;Affects: C,N,Z
|
|
;Returns: A,Y = Total length of concatenated string
|
|
strcat: JSR strini ;Initialize Source String
|
|
strcal: LDA (dstlo),Y ;Find end of Destination String
|
|
BEQ strcax ;
|
|
INY ;
|
|
BPL strcal ;
|
|
strcax: STY temp0 ;Subtract Destination String Length
|
|
LDA strlo ; from Source String Pointer
|
|
SEC
|
|
SBC temp0
|
|
STA strlo
|
|
LDA strhi
|
|
SBC #$00
|
|
STA strhi
|
|
JMP strcpl ;Execute String Copy
|
|
|
|
;strcpy(&s) - Copy String (to Destination String)
|
|
;Requires: dstlo, dsthi - Pointer to destination string
|
|
;Args: X,Y = Pointer to source string
|
|
;Sets: strlo,strhi = Pointer to source string
|
|
;Affects: N,Z
|
|
;Returns: A,Y = Number of characters copies
|
|
strcpy: JSR strini ;Initialize Source String
|
|
strcpl: LDA (strlo),Y ;Get Character from Source String
|
|
STA (dstlo),Y ;Copy to Destination String
|
|
BEQ strcpx ;If <> NUL
|
|
INY ; Increment Index
|
|
BPL strcpl ; and Loop if < 128
|
|
strcpx: TYA ;Transfer Index to Accumulator
|
|
RTS ;and Return
|
|
|
|
;strcut(n, &s) - Copy from Position n to End of Source (into Destination)
|
|
;Requires: dstlo, dsthi - Pointer to destination string
|
|
;Args: A = Starting position in start string
|
|
; X,Y = Pointer to source string
|
|
;Sets: strlo,strhi = Pointer to specified position source string
|
|
;Affects: N,Z
|
|
;Returns: A,Y = Length of copied string
|
|
strcut: JSR strini ;Initialize Source String
|
|
CLC
|
|
ADC strlo ;Move Source Pointer
|
|
STA strlo ; to Specified Position in String
|
|
BCC strcpl
|
|
INC strhi
|
|
JMP strcpl ;and Jump Into String Copy Loop
|
|
|
|
;strstr(&s) - Search for String (in Destination String)
|
|
;Requires: dstlo, dsthi - Pointer to destination string
|
|
;Args: X,Y = Pointer to source string
|
|
;Sets: dstlo,dsthi = Pointer to position in source string
|
|
; End of string if not found
|
|
; strlo,strhi = Pointer to source string
|
|
; temp0 = Last position checked in destination string
|
|
;Affects: N,Z
|
|
;Returns: A = Position, C=1 if found
|
|
; A = $FF, C=0 if not found
|
|
; Y = Last position checked in source string
|
|
strstr: JSR strini ;Initialize Source String
|
|
STY temp0 ;Initialize Position
|
|
strstl: LDY #$00; ;Initialize Compare Offset
|
|
LDA (dstlo),Y ;Get Start Character in Destination
|
|
BEQ strclc ;If NUL return $FF and Carry Clear
|
|
JSR strcml ;Jump into Compare Loop
|
|
BEQ strstx ;If Not Equal
|
|
BMI strstn ; If Source is Greater
|
|
LDA (strlo),Y ; If at End of Source String
|
|
BEQ strstx ; Return Current Position
|
|
strstn: INC temp0 ; Else Increment Position
|
|
BMI strclc ; If > 127 return $FF and Carry Clear
|
|
INC dstlo ; Increment Source Pointer
|
|
BNE strstl
|
|
INC dsthi ; If not End of Memory
|
|
BNE strstl ; Loop
|
|
BEQ strclc ; Else return $FF and Carry Clear
|
|
strstx: SEC ;Else Set Carry
|
|
LDA temp0 ; Load Position
|
|
RTS ; and Return
|
|
|