Here, you can find some tools in assembler 6502 for Commodore 64.
This library, contains some routine to make copy in memory.
memCopy source,dest,count
- source (16bits)
- dest (16bits)
- count (16bits)
Set the address source and destination of copy. Count contains number of byte you want copy.
- Source is store in address $02 and $03 (low/high)
- Dest is store in address $fb and $fc (low/high)
- Count is store in address $fd and $fe (low/high)
Example:
*=$1000
start:
lda #$00 ; source $0400 top of default screen of C64
sta $02
lda #$04
sta $03
lda #$e0 ; destination $05E0 ( 13 lines under )
sta $fb
lda #$05
sta $fc
lda #$a0 ; number of bytes $a0 ( 4*40 -> 4 lines)
sta $fd
lda #$00
sta $fe
jsr memCopy
rts
!source "libs/memtools.a"
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This routine is like memCopy but with modulo. See below :
Source data:
[------ line size (number of bytes -------] ; Here 11 bytes
.byte $80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80 ; line 0
.byte $80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80 ; line 1
.byte $80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80 ; line 2
.byte $80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80 ; line 3
; here count = 4*11
Result on screen:
-------------------------------
| |
| ------ <-----------modu|
|lo--->|data| |
| | | |
| ------ |
| |
| |
-------------------------------
Here modulo is number of bytes between the end of first line and the beginning of the second line
memCopyMod source,dest,count
- source (16bits)
- dest (16bits)
- count (16bits)
- linesize (16bits)
- modulo (16bits)
initialize memCopyMod
- Source is store in address $02 and $03 (low/high)
- Dest is store in address $fb and $fc (low/high)
- Count is store in address $fd and $fe (low/high)
- line size is store in address $62 and $63
- modulo is store in address $66 and $67
Example:
*=$1000
COL = 20
ROW = 6
start:
lda #<mydata
sta $02
lda #>mydata
sta $03
lda #<($0400+(40*ROW+COL)) ; destination on column 20 and row 6
sta $fb
lda #>($0400+(40*ROW+COL))
sta $fc
lda #<(enddata-mydata) ; number of bytes
sta $fd
lda #>(enddata-mydata)
sta $fe
lda #<(sl-mydata) ; linesize
sta $62
lda #>(sl-mydata)
sta $63
lda #<(40-(sl-mydata)) ; modulo
sta $66
lda #>(40-(sl-mydata))
sta $67
jsr memCopyMod
rts
!source "libs/memtools.a"
mydata:
!text " ***** "
sl: !text " * * "
!text "* ^ ^ *"
!text " * 0 0 * "
!text " * o * "
!text " * * "
!text " ***** "
!text " * * "
!text " * * "
enddata:
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- value (8bits)
- dest (16bits)
- count (16bits)
This routine fill memory of value n.
- Value is store in address $02
- Dest is store in address $fb and $fc (low/high)
- Count is store in address $fd and $fe (low/high)
Example:
!to "PRG/mem.prg", cbm
*=$1000
COL = 0
ROW = 10
start:
lda #32+128 ;INVERT SPACE CHAR
sta $02
lda #<($0400+(40*(ROW))+COL) ; destination $05E0
sta $fb
lda #>($0400+(40*(ROW))+COL)
sta $fc
lda #<(40*4) ; number of bytes $a0
sta $fd
lda #>(40*4)
sta $fe
jsr memFill
rts
!source "libs/memtools.a"
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This routine read data from the memory source and write in destination value from a map table. The map table is array with size of 256 bytes
Imagine source data :
$00,$01,$04,$04,$04,$01,$02,...
Map table is :
$F0,$E0,$D0,$C0,$B0,...
Result is destination is :
$F0,$E0,$B0,$B0,$B0,$E0,$F0
- source (16bits)
- dest (16bits)
- count (16bits)
- mapTbale (16 bits)
Set the address source and destination of copy. Count contains number of byte you want copy. Maptable contains the values to convert from source.
- Source is store in address $02 and $03 (low/high)
- Dest is store in address $fb and $fc (low/high)
- Count is store in address $fd and $fe (low/high)
- MapTbale is store in address $62 and $63 (low/high)
Example:
*=$1000
COL = 20
ROW = 6
start:
lda #<mydata
sta $02
lda #>mydata
sta $03
lda #<($0400+(40*ROW+COL)) ; destination on column 20 and row 6
sta $fb
lda #>($0400+(40*ROW+COL))
sta $fc
lda #<(enddata-mydata) ; number of bytes
sta $fd
lda #>(enddata-mydata)
sta $fe
lda #<(sl-mydata) ; linesize
sta $62
lda #>(sl-mydata)
sta $63
lda #<(40-(sl-mydata)) ; modulo
sta $66
lda #>(40-(sl-mydata))
sta $67
jsr memCopyMod
lda #$00 ; source $0400 top of default screen of C64
sta $02
lda #$04
sta $03
lda #$00 ; destination $D800 (color ram)
sta $fb
lda #$D8
sta $fc
lda #$e8 ; number of bytes $3e8 (number of caractère in a screen 40x25)
sta $fd
lda #$03
sta $fe
lda #<mapTable
sta $62
lda #>mapTable
sta $63
jsr memMapper
rts
mapTable:
!byte $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0F
!byte $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0F
!byte $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0F
!byte $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0F
!byte $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0F
!byte $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0F
!byte $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0F
!byte $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0F
!byte $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0F
!byte $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0F
!byte $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0F
!byte $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0F
!byte $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0F
!byte $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0F
!byte $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0F
!byte $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0F
!source "libs/memtools.a"
mydata:
!text " ***** "
sl: !text " * * "
!text "* ^ ^ *"
!text " * 0 0 * "
!text " * o * "
!text " * * "
!text " ***** "
!text " * * "
!text " * * "
enddata:
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