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C02/include/stddef.a02
2019-03-24 16:29:19 -04:00

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;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