2018-07-27 17:38:47 +00:00
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;c02 library stddef.h02 assembly language subroutines
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;Requires External Zero Page Variables
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;DSTLO, DSTHI, SRCLO, SRCHI
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;External Variables
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;TEMP0, TEMP1, TEMP2
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2018-07-27 18:11:39 +00:00
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;Constant Definitions
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2018-07-27 17:38:47 +00:00
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TRUE EQU $FF ;Returned for Success or Failure
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FALSE EQU $00 ;by some Library Routines
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;savdst() - Save Destination Pointer
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SAVDST: JSR GETDST ;Load Destination Pointer
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JMP SAVRXY ;Save X & Y Registers
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;savdst() - Save Destination Pointer
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SAVSRC: JSR GETSRC ;Load Destination Pointer
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JMP SAVRXY ;Save X & Y Registers
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;Save Registers
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SAVREG: STA TEMP0 ;Save Accumulater
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SAVRXY: STX TEMP1 ;Save X Index
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STY TEMP2 ;Save Y Index
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RTS
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;Restore Registers
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RESREG: LDA TEMP0 ;Load Accumlator
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RESRXY: LDX TEMP1 ;Load X Index
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LDY TEMP2 ;Load Y Index
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RTS
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2019-03-23 00:30:49 +00:00
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;Set Destination Pointer to Source Pointer
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2018-07-30 22:35:35 +00:00
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SETDSS: JSR GETSRC ;Get Destination Pointer
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JMP SETDST ;Store in Source Pointer
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2018-07-27 17:38:47 +00:00
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;Restore Destination Pointer
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RESDST: JSR RESRXY ;Load Address and Drop into SETDST
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;Initialize Destination Pointer
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SETDST: STX DSTLO ;Store Destination Pointer
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STY DSTHI
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RTS
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;Restore Source Pointer
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RESSRC: JSR RESRXY ;Load Saved Address
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JMP SETSRC ;Set Source Pointer
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;Set Source Pointer to Destination Pointer
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SETSRD: JSR GETDST ;Get Destination Point and fall into SETSRC
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;Initialize Source Pointer and Index
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SETSRC: STX SRCLO ;Store Source Pointer
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STY SRCHI
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LDY #$00 ;Initialize Index Into String
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RTS
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;Retrieve Source String Pointer
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GETDST: LDX DSTLO
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LDY DSTHI
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RTS
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;Retrieve Source String Pointer
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GETSRC: LDX SRCLO
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LDY SRCHI
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RTS
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2019-03-23 00:30:49 +00:00
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;Add to Destination Address
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ADDDST: LDX #DSTLO ;Set Index
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BNE ADDZPW ;and Execute ADDZPW
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;Add to Source Address
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ADDSRC: LDX #SRCLO ;Set Index and Drop into ADDZPW
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;Add to Zero Page Word
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ADDZPW: CLC ;Clear Carry
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ADC 0,X ;Add Argument to LSB
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STA 0,X ;and Save Result
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BCC ADDZPX ;If Carry
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INC 1,X ; Increment MSB
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ADDZPX: RTS
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