AppleIIAsm-Collection/disks/disk1__stdio_common/T.COMMON.ZBACKUP
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2018-11-03 14:59:24 -04:00

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*``````````````````````````````*
* ZSAVE :: SAVE 0-PAGE FREE *
*- -*
* STORES THE VALUES IN THE *
* LITTLE FREE SPACE ON THE *
* ZERO PAGE AT AN ALTERNATE *
* MEMORY LOCATION TO BE *
* RETRIEVED AND RESTORED AT A *
* LATER POINT. *
*- -*
* CLOBBERS: *
* *
* FLAGS: ????---- REG: AXYM *
*- -*
* CYCLES: ??? *
* SIZE: *
*- -*
* USAGE: *
* *
* LDA #>$6A00 *
* PHA *
* LDA #<$6A00 *
* PHA *
* JSR ZSAVE *
*- -*
* ENTRY *
* *
* TOP OF STACK *
* *
* LOW BYTE OF RETURN ADDRESS *
* HI BYTE OF RETURN ADDRESS *
* LOW BYTE OF DESTINATION *
* HIGH BYTE OF DESTINATION *
*- -*
* EXIT *
* *
* TOP OF STACK *
* *
* LOW BYTE OF RETURN ADDRESS *
* HI BYTE OF RETURN ADDRESS *
* *
* Y = TRASH *
* X = TRASH *
* A = LOW BYTE OF RET ADDR *
*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
*
ZSAVE
*
** LOAD ADDR1 ZERO PAGE AREA FIRST,
** SINCE WE'LL BE USING THAT
*
** NOTE THAT THIS SHOULD ALWAYS BE
** $06 AND $07, OR ELSE CODE WILL
** HAVE TO CHANGE.
*
LDX ADDR1
LDY ADDR1+1
*
** SAVE RETURN ADDRESS
*
PLA
STA :RETADR
PLA
STA :RETADR+1
*
** GET PARAMETERS
*
PLA
STA ADDR1
PLA
STA ADDR1+1
*
** COPY ZERO PAGE TO SPECIFIED
** NON-ZERO LOCATION (ONLY THE
** FREE ONES..)
*
TYA ; STORE ADDR1 VALS
LDY #1 ; FIRST
STA (ADDR1),Y
LDY #0
TXA
STA (ADDR1),Y
LDY #2
LDA $08
STA (ADDR1),Y
INY
LDA $09
STA (ADDR1),Y
INY
LDA $19
STA (ADDR1),Y
INY
LDA $1E
STA (ADDR1),Y
INY
LDA $E3
STA (ADDR1),Y
INY
LDA $EB
STA (ADDR1),Y
INY
LDA $EC
STA (ADDR1),Y
INY
LDA $ED
STA (ADDR1),Y
INY
LDA $EE
STA (ADDR1),Y
INY
LDA $EF
STA (ADDR1),Y
INY
LDA $FA
STA (ADDR1),Y
INY
LDA $FB
STA (ADDR1),Y
INY
LDA $FC
STA (ADDR1),Y
INY
LDA $FD
STA (ADDR1),Y
INY
LDA $FE
STA (ADDR1),Y
INY
LDA $FF
STA (ADDR1),Y
*
** RESTORE RETURN ADDRESS
*
LDA :RETADR+1
PHA
LDA :RETADR
PHA
*
RTS
*
** DATA
*
:RETADR DS 2
*
*``````````````````````````````*
* ZLOAD :: RESTORE 0-PAGE FREE *
*- -*
* RESTORES PREVIOUSLY SAVED *
* ZERO PAGE VALUES FROM *
* HIGHER MEMORY LOCATION. *
* CLOBBERS: *
* *
* FLAGS: ????---- REG: AXYM *
*- -*
* CYCLES: ??? *
* SIZE: *
*- -*
* USAGE: *
* *
* LDA #>$6A00 *
* PHA *
* LDA #<$6A00 *
* PHA *
* JSR ZLOAD *
*- -*
* ENTRY *
* *
* TOP OF STACK *
* *
* LOW BYTE OF RETURN ADDRESS *
* HI BYTE OF RETURN ADDRESS *
* LOW BYTE OF SOURCE *
* HIGH BYTE OF SOURCE *
*- -*
* EXIT *
* *
* TOP OF STACK *
* *
* LOW BYTE OF RETURN ADDRESS *
* HI BYTE OF RETURN ADDRESS *
* *
*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
*
ZLOAD
*
** SAVE RETURN ADDRESS
*
PLA
STA :RETADR
PLA
STA :RETADR+1
*
** GET PARAMETERS
*
PLA
STA ADDR1
PLA
STA ADDR1+1
*
** COPY ZERO PAGE TO SPECIFIED
** NON-ZERO LOCATION (ONLY THE
** FREE ONES..)
*
LDY #2 ; START 2 AHEAD
LDA (ADDR1),Y ; AND PUT ADDR1
STA $08 ; AREA LAST
INY
LDA (ADDR1),Y
STA $09
INY
LDA (ADDR1),Y
STA $19
INY
LDA (ADDR1),Y
STA $1E
INY
LDA (ADDR1),Y
STA $E3
INY
LDA (ADDR1),Y
STA $EB
INY
LDA (ADDR1),Y
STA $EC
INY
LDA (ADDR1),Y
STA $ED
INY
LDA (ADDR1),Y
STA $EE
INY
LDA (ADDR1),Y
STA $EF
INY
LDA (ADDR1),Y
STA $FA
INY
LDA (ADDR1),Y
STA $FB
INY
LDA (ADDR1),Y
STA $FC
INY
LDA (ADDR1),Y
STA $FD
INY
LDA (ADDR1),Y
STA $FE
INY
LDA (ADDR1),Y
STA $FF
*
** NOW GET ZERO PAGE VALUES
** FOR SPACE OCCUPIED BY ADDR; RETURN IN X,Y
*
LDY #0
LDA (ADDR1),Y
TAX
LDA (ADDR1+1),Y
TAY
STX ADDR1
STY ADDR1+1
*
** RESTORE RETURN ADDRESS
*
LDA :RETADR+1
PHA
LDA :RETADR
PHA
*
RTS
*
** DATA
*
:RETADR DS 2
*
*
COMMONX RTS