mirror of
https://github.com/RevCurtisP/C02.git
synced 2024-11-22 01:31:33 +00:00
100 lines
2.8 KiB
Plaintext
100 lines
2.8 KiB
Plaintext
;c02 library stddef.h02 assembly language subroutines
|
|
;Requires External Zero Page Variables
|
|
;DSTLO, DSTHI, SRCLO, SRCHI
|
|
;External Variables
|
|
;TEMP0, TEMP1, TEMP2
|
|
|
|
;Constant Definitions
|
|
TRUE EQU $FF ;Returned for Success or Failure
|
|
FALSE EQU $00 ;by some Library Routines
|
|
|
|
;savdst() - Save Destination Pointer
|
|
SAVDST: JSR GETDST ;Load Destination Pointer
|
|
JMP SAVRXY ;Save X & Y Registers
|
|
|
|
;savsrc() - Save Source Pointer
|
|
SAVSRC: JSR GETSRC ;Load Destination Pointer
|
|
JMP SAVRXY ;Save X & Y Registers
|
|
|
|
;Save Registers
|
|
SAVREG: STA TEMP0 ;Save Accumulater
|
|
SAVRXY: STX TEMP1 ;Save X Index
|
|
STY TEMP2 ;Save Y Index
|
|
RTS
|
|
|
|
;Restore Registers
|
|
RESREG: LDA TEMP0 ;Load Accumlator
|
|
RESRXY: LDX TEMP1 ;Load X Index
|
|
LDY TEMP2 ;Load Y Index
|
|
RTS
|
|
|
|
;Set Destination Pointer to Source Pointer
|
|
SETDSS: JSR GETSRC ;Get Destination Pointer
|
|
JMP SETDST ;Store in Source Pointer
|
|
|
|
;Restore Destination Pointer
|
|
RESDST: JSR RESRXY ;Load Address and Drop into SETDST
|
|
|
|
;Initialize Destination Pointer
|
|
SETDST: STX DSTLO ;Store Destination Pointer
|
|
STY DSTHI
|
|
RTS
|
|
|
|
;Restore Source Pointer
|
|
RESSRC: JSR RESRXY ;Load Saved Address
|
|
JMP SETSRC ;Set Source Pointer
|
|
|
|
;Set Source Pointer to Destination Pointer
|
|
SETSRD: JSR GETDST ;Get Destination Point and fall into SETSRC
|
|
|
|
;Initialize Source Pointer and Index
|
|
SETSRC: STX SRCLO ;Store Source Pointer
|
|
STY SRCHI
|
|
LDY #$00 ;Initialize Index Into String
|
|
RTS
|
|
|
|
;Retrieve Source String Pointer
|
|
GETDST: LDX DSTLO
|
|
LDY DSTHI
|
|
RTS
|
|
|
|
;Retrieve Source String Pointer
|
|
GETSRC: LDX SRCLO
|
|
LDY SRCHI
|
|
RTS
|
|
|
|
;Add Accumulator to Destination Address
|
|
ADDDSA: TAX ;Move Accumulator to Argument LSB
|
|
LDY #0 ;Clear Argument MSB
|
|
|
|
;Add to Destination Address
|
|
;Args: Y,X = MSB,LSB of Integer to Add
|
|
;Affects: A,Y,X
|
|
ADDDST: LDA #DSTLO ;Set Index to Destination Pointer
|
|
BNE ADDZPW ;and Execute ADDZPW
|
|
|
|
;Add Accumulator to Source Address
|
|
ADDSRA: TAX ;Move Accumulator to Argument LSB
|
|
LDY #0 ;Clear Argument MSB
|
|
|
|
;Add to Source Address
|
|
;Args: Y,X = MSB,LSB of Integer to Add
|
|
;Affects: A,Y,X
|
|
ADDSRC: LDA #SRCLO ;Set Index and Drop into ADDZPW
|
|
|
|
;Add to Zero Page Word
|
|
;Args: A = Address of Zero Page Word
|
|
; Y,X = MSB,LSB of Integer to Add
|
|
;Affects: A
|
|
ADDZPW: STA TEMP3 ;Save Zero Page Address
|
|
TXA ;Move Argument LSB to Accumulator
|
|
LDX TEMP3 ;Set Index to Zero Page Address
|
|
CLC ;Clear Carry
|
|
ADC 0,X ;Add Argument LSB to Target LSB
|
|
STA 0,X ;and Save Result
|
|
TYA ;Move Argument MSB to Accumulator
|
|
ADC 1,X ;Add Argument MSB to Target MSB
|
|
STA 1,X ;and Save Result
|
|
RTS
|
|
|