WIP
This commit is contained in:
Joshua Bell
parent
42dc31e40e
commit
ed1277cc4d
171
path.s
171
path.s
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@ -8,6 +8,8 @@
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.org $2000
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.include "apple2.inc"
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.include "apple2.mac"
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.include "prodos.inc"
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;;; ============================================================
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@ -20,7 +22,20 @@ INBUF := $200 ; GETLN input buffer
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CROUT := $FD8E
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COUT := $FDED
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MOVE := $FE2C ; call with Y=0
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MOVE_SRC := $3C
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MOVE_END := $3E
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MOVE_DST := $42
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TOKEN_NAME_TABLE := $D0D0
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CASE_MASK = $DF
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;;; ============================================================
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;;; Install the new command
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;; TODO: Fail if Applesoft is not in ROM
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;; Save previous external command address
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lda EXTRNCMD+1
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@ -28,34 +43,54 @@ COUT := $FDED
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lda EXTRNCMD+2
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sta next_command+1
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;; Request a 1-page buffer
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lda #1
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;; Request a 2-page buffer
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lda #2
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jsr GETBUFR
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bcc :+
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lda #$C ; NO BUFFERS AVAILABLE
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rts
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:
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;; A = MSB of new page - update absolute addresses
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;; (aligned to page boundary so only MSB changes)
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: sta new_page ; A = MSB of new page
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;; Compute move delta in pages
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lda #>handler
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sec
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sbc new_page
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sta page_delta
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;; Relocatable routine is aligned to page boundary so only MSB changes
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ldx relocation_table
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: ldy relocation_table+1,x
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lda handler,y
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clc
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adc page_delta
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sta handler,y
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dex
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bpl :-
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;; Relocate
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lda #<handler
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sta MOVE_SRC
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lda #>handler
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sta MOVE_SRC+1
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lda #<handler_end
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sta MOVE_END
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lda #>handler_end
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sta MOVE_END+1
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lda #0
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sta MOVE_DST
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lda new_page
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sta MOVE_DST+1
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ldy #0
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jsr MOVE
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;; Install new address in external command address
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lda new_page
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sta EXTRNCMD+2
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lda #0
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sta EXTRNCMD+1
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;; Relocate
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ldx #0
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: lda handler,x
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page_num3 := *+2
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sta $2100,x ; self-modified
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inx
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bne :-
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;; Complete
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rts
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@ -68,21 +103,19 @@ COUT := $FDED
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.res $2100 - *, 0
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.proc handler
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ptr := $06
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;; Check for this command, character by character.
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ldx #0
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nxtchr: lda INBUF,x
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;; TODO: skip leading spaces
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and #$7F ; Convert to ASCII
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cmp #'a' ; Convert to upper-case
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bcc :+
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cmp #'z'+1
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bcs :+
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and #$DF
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nxtchr: lda INBUF,x
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page_num6 := *+2 ; address needing updating
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jsr to_upper
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page_num1 := *+2 ; address needing updating
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: cmp command_string,x
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bne not_path
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cmp command_string,x
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bne check_if_token
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inx
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cpx #command_length
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bne nxtchr
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@ -115,15 +148,75 @@ nxtchr: lda INBUF,x
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;;; ============================================================
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not_path:
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check_if_token:
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;; Ensure it's alpha
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lda INBUF
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page_num7 := *+2 ; address needing updating
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jsr to_upper
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cmp #'A'|$80
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bcc not_ours
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cmp #('Z'+1)|$80
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bcs not_ours
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;; Check if it's a BASIC token. Based on the AppleSoft BASIC source.
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;; Point ptr at TOKEN_NAME_TABLE less one page (will advance below)
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lda #<(TOKEN_NAME_TABLE-$100)
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sta ptr
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lda #>(TOKEN_NAME_TABLE-$100)
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sta ptr+1
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;; These start at "-1" and are immediately incremented
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ldx #$FF ; X = position in input line
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ldy #$FF ; (ptr),y offset TOKEN_NAME_TABLE
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;; Match loop
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mloop: iny ; Advance through token table
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bne :+
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inc ptr+1
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: inx
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;; Check for match
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next_char:
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lda INBUF,x ; Next character
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page_num8 := *+2 ; address needing updating
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jsr to_upper
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;; NOTE: Does not skip over spaces, unlike BASIC tokenizer
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sec ; Compare by subtraction..
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sbc (ptr),Y
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beq mloop
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cmp #$80 ; If only difference was the high bit
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beq not_ours ; then it's end-of-token -- and a match!
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;; Otherwise, advance to next token
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next_token:
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ldx #0 ; Start next match at start of input line
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;; TODO: skip leading spaces
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@loop: lda (ptr),y ; Scan table looking for a high bit set
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iny
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bne :+
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inc ptr+1
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: asl
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bcc @loop ; High bit clear, keep looking
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lda (ptr),y ; End of table?
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bne next_char ; Nope, check for a match
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;; Not a keyword, so invoke
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not_a_token:
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;; TODO: Implement me!
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;;; ============================================================
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not_ours:
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sec ; Signal failure...
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next_command := *+1
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jmp $ffff ; Execute next command in chain
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;;; ============================================================
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;;; ============================================================
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execute:
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@ -137,10 +230,10 @@ execute:
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;; Show current path
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ldx #0
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page_num3 := *+2
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page_num3 := *+2 ; address needing updating
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: cpx path_buffer
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beq done
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page_num4 := *+2
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page_num4 := *+2 ; address needing updating
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lda path_buffer+1,x
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ora #$80
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jsr COUT
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@ -154,7 +247,6 @@ done: clc
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;;; --------------------------------------------------
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;; Set path
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set_path:
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ptr := $06
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lda VPATH1
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sta ptr
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ldx VPATH1+1
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@ -164,27 +256,43 @@ set_path:
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lda (ptr),y
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tay
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: lda (ptr),y
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page_num5 := *+2
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page_num5 := *+2 ; address needing updating
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sta path_buffer,y
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dey
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bpl :-
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clc
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rts
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;;; ============================================================
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;;; Helpers
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.proc to_upper
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cmp #'a'|$80
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bcc skip
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and #CASE_MASK
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skip: rts
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.endproc
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;;; ============================================================
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;;; Data
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command_string:
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.byte "PATH" ; Command string
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scrcode "PATH"
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command_length = *-command_string
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path_buffer:
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.res 65, 0
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.endproc
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.assert .sizeof(handler) <= $100, error, "Must fit on one page"
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.assert .sizeof(handler) <= $200, error, "Must fit on two pages"
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handler_end := *-1
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next_command := handler::next_command
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new_page:
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.byte 0
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page_delta:
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.byte 0
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relocation_table:
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.byte 5
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.byte <handler::page_num1
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@ -192,3 +300,6 @@ relocation_table:
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.byte <handler::page_num3
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.byte <handler::page_num4
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.byte <handler::page_num5
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.byte <handler::page_num6
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.byte <handler::page_num7
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.byte <handler::page_num8
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