AppleIIAsm-Collection/source/disk5_strings/T.SUB.SUBINS

240 lines
6.1 KiB
Plaintext
Raw Normal View History

2018-11-15 00:02:04 +00:00
*``````````````````````````````*
* SUBINS :: INSERT SUBSTRING *
*- -*
* INSERT A SUBSTRING INTO *
* ANOTHER STRING. *
*- -*
* CLOBBERS: *
* *
* FLAGS: ????---- REG: AXYM *
*- -*
* CYCLES: ??? *
* SIZE: *
*- -*
* USAGE: *
* *
* LDA #STR ; STRING TO INS TO *
* PHA *
* LDA #<STR *
* PHA *
* LDA IND ; INDEX TO START INS *
* PHA *
* LDA MLEN ; MAX LENGTH OF STR *
* PHA *
* LDA #>SUB ; SUBSTRING TO INS *
* PHA *
* LDA #<SUB *
* PHA *
* JST SUBINS *
*- -*
* ENTRY *
* *
* TOP OF STACK *
* *
* LOW BYTE OF RETURN ADDRESS *
* HI BYTE OF RETURN ADDRESS *
* LO BYTE OF SUBSTRING ADDRESS *
* HI BYTE OF SUBSTRING ADDRESS *
* MAX LENGTH OF FINAL STRING *
* STARTING INDEX FOR INSERTION *
* LO BYTE OF SRC STRING ADDR *
* HI BYTE OF SOURCE STR ADDR *
*- -*
* EXIT *
* *
* TOP OF STACK *
* *
* LOW BYTE OF RETURN ADDRESS *
* HI BYTE OF RETURN ADDRESS *
* *
* .Y = TRASH *
* .X = TRASH *
* .A = TRASH *
2018-11-15 00:02:04 +00:00
* *
* CARRY = 0 IF NO ERRORS; ELSE *
* CARRY = 1 *
*- -*
* ADAPTED FROM LEVANTHAL AND *
* WINTHROP'S /6502 ASSEMBLY *
* LANGUAGE ROUTINES/. *
*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
*
SUBINS
*
** GET RETURN ADDRESS
*
PLA
TAY
PLA
TAX
*
** GET PARAMETERS
*
PLA
STA ADDR2
PLA
STA ADDR2+1
PLA
STA :MLEN
PLA
STA :SINDEX
PLA
STA ADDR1
PLA
STA ADDR1+1
*
** RESTORE RETURN ADDRESS
*
TXA
PHA
TYA
PHA
*
*
** ASSUME NO ERRORS
*
LDA #0
STA :SCERR ; ASSUME NO ERR WILL BE FOUND
*
** GET SUBSTRING AND STRING LENGTHS
** IF SUB LENGTH = 0 THEN EXIT NO ERROR
*
LDY #0
LDA (ADDR1),Y
STA :S1LEN ; GET LENGTH OF STRING
LDA (ADDR2),Y
STA :S2LEN ; GET LENGTH OF SUB
BNE :IDX0
JMP :OKEXIT ; EXIT OF NO INSERT/ERR
*
** IF STARTING INDEX IS 0 THEN ERROR EXIT
*
:IDX0
LDA :SINDEX
BNE :CHKLEN ; BR OF INDEX NOT 0
JMP :EREXIT ; ELSE ERROR EXIT
*
** CHECK THAT THE RESULTING STRING AFTER THE
** INSERTION FITS IN THE SOURCE STRING. IF NOT
** THEN TRUNCATE THE SUBSTRING AND SET
** THE TRUNCATION FLAG.
*
:CHKLEN
LDA :S2LEN ; GET SUBSTR LENGTH
CLC
ADC :S1LEN
BCS :TRUNC ;TRUN IF S1+S2 LENGTH > 255
CMP :MLEN ;
BCC :IDXLEN ; BR IF S1+S2 LEN < MAX LENGTH
BEQ :IDXLEN ; BR IF EQUAL
*
** SUBSTRING DOES NOT FIT, SO TRUNCATE IT
*
:TRUNC
LDA :MLEN ; SUBSTR LEN = MLEN - STR LEN
SEC
SBC :S1LEN
BCC :EREXIT
BEQ :EREXIT ; ERR IF MLEN < STR LEN OR 0
; (ORIGINAL STRING WAS TOO LONG)
STA :S2LEN
LDA #$0FF
STA :SCERR ; INDICATE SUBSTR WAS TRUNCATED
*
** CHECK THAT INDEX IS WITHIN STRING. IF NOT, CONCAT
** SUBSTR ONTO THE END OF THE STRING.
*
:IDXLEN
LDA :S1LEN
CMP :SINDEX ;
BCS :LENOK ; BR IF INDEX WITHIN STR
LDX :S1LEN ; ELSE CONCAT SUB AT END OF STR
INX
STX :SINDEX ; START RIGHT AFTER END OF STR
LDA #$0FF
STA :SCERR ; INDICATE ERR IN INSERT
LDA :S1LEN
CLC
ADC :S2LEN
STA :S1LEN ; ADD LENGTHS TOGETHER
JMP :MVESUB ; PERFORM MOVE, NOTHING ELSE TODO
*
** OPEN UP A SPACE IN THE SOURCE STRING FOR THE
** SUBSTRING BY MOVING THE CHARACTERS FROM THE END
** OF THE SOURCE STRING DOWN TO INDEX, UP BY
** THE SIZE OF THE STRING.
*
:LENOK
*
** CALC NUMBER OF CHARS TO MOVE
** COUNT = STR LEN - START INDEX + 1
*
LDA :S1LEN
SEC
SBC :SINDEX
TAX
INX ; X= NUM OF CHARS TO MOV
*
** SET THE SOURCE INDEX AND CALC DEST INDEX
*
LDA :S1LEN
STA :SIDX ; SRC ENDS AT ORIG STR END
CLC
ADC :S2LEN
STA :SBIDX ; DEST ENDS FURTHER BY SUB LEN
STA :S1LEN ; SET NEW LENGTH TO THIS ALSO
*
:OPNLP
LDY :SIDX
LDA (ADDR1),Y
LDY :SBIDX
STA (ADDR1),Y ; MOVE IT UP IN MEM
DEC :SIDX
DEC :SBIDX ; DE DEST IDX, COUNTER
DEX
BNE :OPNLP ; CONT UNTIL COUNTER = 0
*
** MOVE THE SUBSTR INTO THE OPEN AREA
*
:MVESUB
LDA #1
STA :SIDX
; START AT ONE IN THE SUBSTR
; START AT INDEX IN THE STRING
LDX :S2LEN ; X = NUM OF CHARS TO MOVE
*
:MVELP
LDY :SIDX
LDA (ADDR2),Y ; GET NEXT CHAR
LDY :SINDEX
STA (ADDR1),Y
INC :SIDX ; INC SUBSTR INDEX
INC :SINDEX ; INC STR INDEX
DEX ; DEC COUNTER
BNE :MVELP ; CONT UNTIL COUNTER = 0
LDA :SCERR ; GET ERROR FLAG
BNE :EREXIT ; BR IF SUBSTR WAS TRUNCED
*
:OKEXIT
CLC
BCC :EXIT
:EREXIT
SEC ; ERROR EXIT
:EXIT
LDA :S1LEN
LDY #0
STA (ADDR1),Y
RTS
*
** DATA
*
:S1LEN DS 1
:S2LEN DS 1
:SUBLEN DS 1
:MLEN DS 1
:SINDEX DS 1
:SIDX DS 1
:SBIDX DS 1
:SCERR DS 1
*