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text-engine.asm
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text-engine.asm
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; asmsyntax=ca65
.segment "PAGE_FIXED"
; Redefining ASCII code points
;.include "font.map.asm"
;.charmap ' ', $FF ; The only one that can't really be auto-generated
SPACE_WIDTH = 5
; Clear a set of 16 tiles, starting at the address in AddressPointer0
; X holds values for first bit plane
; A holds values for second bit plane
ClearTileRow:
pha
bit $2002
lda AddressPointer0+1
sta $2006
lda AddressPointer0+0
sta $2006
pla
.repeat 16
.repeat 8
stx $2007
.endrepeat
.repeat 8
sta $2007
.endrepeat
.endrepeat
rts
WriteBufferUnrolled:
bit $2002
lda AddressPointer0+1
sta $2006
lda AddressPointer0+0
sta $2006
.repeat 16, B
.repeat 8, C
lda ChrBuffer + ((B*8) + C)
sta $2007
.endrepeat
lda #0
.repeat 8
sta $2007
.endrepeat
.endrepeat
lda #$00
sta ChrBufferReady
rts
;Text_ResetTiles_8:
; bit $2002
; lda AddressPointer0+1
; sta $2006
; lda AddressPointer0+0
; sta $2006
;
; lda #0
; .repeat 8*16
; sta $2007
; .endrepeat
; rts
;
;Text_ResetTiles_15:
; bit $2002
; lda AddressPointer0+1
; sta $2006
; lda AddressPointer0+0
; sta $2006
;
; lda #0
; .repeat 15*16
; sta $2007
; .endrepeat
; rts
; A has count
; X has the BG palette value thing in it
WriteTextBuffer_LevelSelect_15:
bit $2002
lda AddressPointer0+1
sta $2006
lda AddressPointer0+0
sta $2006
ldy #0
.repeat 17, i
lda ChrBuffer+(i*8)+0
sta $2007
lda ChrBuffer+(i*8)+1
sta $2007
lda ChrBuffer+(i*8)+2
sta $2007
lda ChrBuffer+(i*8)+3
sta $2007
lda ChrBuffer+(i*8)+4
sta $2007
lda ChrBuffer+(i*8)+5
sta $2007
lda ChrBuffer+(i*8)+6
sta $2007
lda ChrBuffer+(i*8)+7
sta $2007
; Second plane
.repeat 8
sty $2007
.endrepeat
.endrepeat
lda #$00
sta ChrBufferReady
rts
WriteTextBuffer_LevelSelect_7:
bit $2002
lda AddressPointer0+1
sta $2006
lda AddressPointer0+0
sta $2006
ldy #0
.repeat 8, i
lda ChrBuffer+((i+8)*8)+0
sta $2007
lda ChrBuffer+((i+8)*8)+1
sta $2007
lda ChrBuffer+((i+8)*8)+2
sta $2007
lda ChrBuffer+((i+8)*8)+3
sta $2007
lda ChrBuffer+((i+8)*8)+4
sta $2007
lda ChrBuffer+((i+8)*8)+5
sta $2007
lda ChrBuffer+((i+8)*8)+6
sta $2007
lda ChrBuffer+((i+8)*8)+7
sta $2007
; Second plane
.repeat 8
sty $2007
.endrepeat
.endrepeat
lda #$00
sta ChrBufferReady
rts
WriteTextBuffer_LevelSelect_8:
bit $2002
lda AddressPointer0+1
sta $2006
lda AddressPointer0+0
sta $2006
ldy #0
.repeat 8, i
lda ChrBuffer+(i*8)+0
sta $2007
lda ChrBuffer+(i*8)+1
sta $2007
lda ChrBuffer+(i*8)+2
sta $2007
lda ChrBuffer+(i*8)+3
sta $2007
lda ChrBuffer+(i*8)+4
sta $2007
lda ChrBuffer+(i*8)+5
sta $2007
lda ChrBuffer+(i*8)+6
sta $2007
lda ChrBuffer+(i*8)+7
sta $2007
; Second plane
.repeat 8
sty $2007
.endrepeat
.endrepeat
lda #$00
sta ChrBufferReady
rts
; A has count
; X has the BG palette value thing in it
WriteTextBuffer_LevelSelect:
sta ChrCount
bit $2002
lda AddressPointer0+1
sta $2006
lda AddressPointer0+0
sta $2006
ldy #0
ldx #0
@loop:
lda ChrBuffer, x
sta $2007
lda ChrBuffer+1, x
sta $2007
lda ChrBuffer+2, x
sta $2007
lda ChrBuffer+3, x
sta $2007
lda ChrBuffer+4, x
sta $2007
lda ChrBuffer+5, x
sta $2007
lda ChrBuffer+6, x
sta $2007
lda ChrBuffer+7, x
sta $2007
; Second plane
.repeat 8
sty $2007
.endrepeat
txa
clc
adc #8
tax
;cpx #0
cpx #(18*8)
bcs @done
beq @done
dec ChrCount
lda ChrCount
bne @loop
@done:
lda #$00
sta ChrBufferReady
sta TextEor
rts
; A has count
; X has the BG palette value thing in it
PreparePartialTextWrite:
sta ChrCount
txa
sta BgTextPal
lda #0
sta TextIdx
lda #$FF
sta TextEor
rts
; Similar to WriteTextBuffer, but only
; writes a few tiles. (one for now)
WritePartialTextBuffer:
bit $2002
lda AddressPointer6+1
sta $2006
lda AddressPointer6+0
sta $2006
ldx TextIdx
.repeat 8,i
lda ChrBuffer+i, x
eor TextEor
sta $2007
.endrepeat
txa
clc
adc #8
sta TextIdx
; Second plane
lda BgTextPal
.repeat 8
sta $2007
.endrepeat
clc
lda #16
adc AddressPointer6+0
sta AddressPointer6+0
bcc :+
inc AddressPointer6+1
:
lda #0
sta $2005
sta $2005
rts
; A has count
; X has the BG palette value thing in it
WriteTextBuffer:
sta ChrCount
txa
pha
bit $2002
lda AddressPointer0+1
sta $2006
lda AddressPointer0+0
sta $2006
ldy #0
ldx #0
@loop:
lda ChrBuffer, x
eor TextEor
sta $2007
lda ChrBuffer+1, x
eor TextEor
sta $2007
lda ChrBuffer+2, x
eor TextEor
sta $2007
lda ChrBuffer+3, x
eor TextEor
sta $2007
lda ChrBuffer+4, x
eor TextEor
sta $2007
lda ChrBuffer+5, x
eor TextEor
sta $2007
lda ChrBuffer+6, x
eor TextEor
sta $2007
lda ChrBuffer+7, x
eor TextEor
sta $2007
; Second plane
pla
pha
.repeat 8
sta $2007
.endrepeat
txa
clc
adc #8
tax
;cpx #0
cpx #(18*8)
bcs @done
beq @done
dec ChrCount
lda ChrCount
bne @loop
@done:
pla
lda #$00
sta ChrBufferReady
sta TextEor
rts
TextClearBuffer:
lda #0
ldx #0
:
.repeat 8
sta ChrBuffer, x
inx
.endrepeat
cpx #(21 * 8)
bne :-
rts
TextClearStringBuffer:
lda #0
sta TextBuffer
ldx #1
:
sta TextBuffer, x
inx
sta TextBuffer, x
inx
cpx #21
bne :-
rts
txt_InsertSpace_v3:
lda #SPACE_WIDTH
sta ChrWidth
clc
adc ChrOffset
sec
sbc #8
cmp #0
bpl @overflow
; Underflow
lda #SPACE_WIDTH
clc
adc ChrOffset
sta ChrOffset
inc TextIdx
jmp txt_loadChar_v3
; Overflow or even
@overflow:
sta ChrOffset
lda ChrBufferIdx
clc
adc #8
sta ChrBufferIdx
inc TextIdx
jmp txt_loadChar_v3
TextPrepare_v3:
; Start by clearing the buffer so we don't
; have to do it later (and screw it up).
jsr TextClearBuffer
ldx #0
stx ChrOffset
stx TextIdx
stx ChrBufferIdx
txt_loadChar_v3:
; Load a character from text
ldy TextIdx
ldx TextBuffer, y
beq @exit ; Null terminated name
; Check for end (in characters)
cpy #21 ; Length of the buffer
bcc @noExit
@exit:
lda #$FF
sta ChrBufferReady
rts
@noExit:
cpx #$FF ; check for space
beq txt_InsertSpace_v3
; Get width
lda FontWidths, x
; Find overflow ammount
; Curret offset + character width - 8
sta ChrWidth ; This might not be needed
clc
adc ChrOffset
sec
sbc #8
; A now holds number of columns that overflow
sta ChrOverflow
; Character ID -> word offset
txa
asl a
tax
; Lookup tile data
lda FontLookup, x
sta TextPointer
lda FontLookup+1, x
sta TextPointer+1
lda #0
sta ChrCurrentRow
; Start of orig row loop
ldy ChrCurrentRow ; 4
ldx #0
.repeat 8, i
lda (TextPointer), y ; 3 * 8 ; get tile data byte for current row
sta WorkingRuneA+i ; 4 * 8
stx WorkingRuneB+i
iny ; 2 * 8
.endrepeat
; get the absolute value of ChrOffset
bit ChrOffset
bpl :+
lda #0
sec
sbc ChrOffset
tax
jmp :++
:
ldx ChrOffset
:
lda txt_ShiftJmpTable_Lo, x ;4
sta AddressPointer0+0 ; 3
lda txt_ShiftJmpTable_Hi, x ;4
sta AddressPointer0+1 ; 3
jmp (AddressPointer0); 5
txt_ShiftJmpTable_Hi:
.hibytes txt_Shift0
.hibytes txt_Shift1
.hibytes txt_Shift2
.hibytes txt_Shift3
.hibytes txt_Shift4
.hibytes txt_Shift5
.hibytes txt_Shift6
.hibytes txt_Shift7
txt_ShiftJmpTable_Lo:
.lobytes txt_Shift0
.lobytes txt_Shift1
.lobytes txt_Shift2
.lobytes txt_Shift3
.lobytes txt_Shift4
.lobytes txt_Shift5
.lobytes txt_Shift6
.lobytes txt_Shift7
txt_Shift7:
.repeat 8, i
ror WorkingRuneA+i
ror WorkingRuneB+i
.endrepeat
txt_Shift6:
.repeat 8, i
ror WorkingRuneA+i
ror WorkingRuneB+i
.endrepeat
txt_Shift5:
.repeat 8, i
ror WorkingRuneA+i
ror WorkingRuneB+i
.endrepeat
txt_Shift4:
.repeat 8, i
ror WorkingRuneA+i
ror WorkingRuneB+i
.endrepeat
txt_Shift3:
.repeat 8, i
ror WorkingRuneA+i
ror WorkingRuneB+i
.endrepeat
txt_Shift2:
.repeat 8, i
ror WorkingRuneA+i
ror WorkingRuneB+i
.endrepeat
txt_Shift1:
.repeat 8, i
ror WorkingRuneA+i
ror WorkingRuneB+i
.endrepeat
txt_Shift0:
; OR the first tile onto the current tile
ldx ChrBufferIdx
.repeat 8, i
lda WorkingRuneA+i
ora ChrBuffer+i, x
sta ChrBuffer+i, x
.endrepeat
; copy the second tile onto the next (blank) tile
.repeat 8, i
lda WorkingRuneB+i
sta ChrBuffer+8+i, x
.endrepeat
lda ChrBufferIdx
clc
adc #8
sta ChrBufferIdx
; A < 0 Room left on tile
; A == 0 No room, no overflow
; A > 0 Overflow into next tile
lda ChrOverflow
beq @tileEven
cmp #0
bpl @overflow
; Underflow
lda ChrWidth
clc
adc ChrOffset
sta ChrOffset
; Back up the buffer index to the start
; of the previous tile
lda ChrBufferIdx
sec
sbc #8
sta ChrBufferIdx
jmp @loadNext
@tileEven:
lda #0
sta ChrOffset
ldx ChrBufferIdx
.repeat 8, I
sta ChrBuffer+I, x
.endrepeat
@loadNext:
; Move to next letter
inc TextIdx
jmp txt_loadChar_v3
; Second tile
@overflow:
lda #0
sta ChrCurrentRow
; ChrShiftLeft has the number of overflowed
; columns. This needs to be the number of times
; to shift left instead (like the name suggests)
;lda ChrWidth
;clc
;adc #8
;sec
;sbc ChrOffset
;sta ChrOffset
lda #8
sec
sbc ChrOffset
sta ChrShiftLeft
; Next char's offset
lda ChrWidth
sec
sbc ChrShiftLeft
sta ChrOffset
; Back up a tile
;lda ChrBufferIdx
;sec
;sbc #8
;sta ChrBufferIdx
inc TextIdx
jmp txt_loadChar_v3
txt_InsertSpace_v2:
lda #SPACE_WIDTH
sta ChrWidth
clc
adc ChrOffset
sec
sbc #8
cmp #0
bpl @overflow
; Underflow
lda #SPACE_WIDTH
clc
adc ChrOffset
sta ChrOffset
inc TextIdx
jmp txt_loadChar_v2
; Overflow or even
@overflow:
sta ChrOffset
lda ChrBufferIdx
clc
adc #8
sta ChrBufferIdx
inc TextIdx
jmp txt_loadChar_v2
TextPrepare_v2:
; Start by clearing the buffer so we don't
; have to do it later (and screw it up).
jsr TextClearBuffer
ldx #0
stx ChrOffset
stx TextIdx
stx ChrBufferIdx
txt_loadChar_v2:
; Load a character from text
ldy TextIdx
ldx TextBuffer, y
beq @exit ; Null terminated name
; Check for end (in characters)
cpy #21 ; Length of the buffer
bcc @noExit
@exit:
lda #$FF
sta ChrBufferReady
rts
@noExit:
cpx #$FF ; check for space
beq txt_InsertSpace_v2
; Get width
lda FontWidths, x
; Find overflow ammount
; Curret offset + character width - 8
sta ChrWidth ; This might not be needed
clc
adc ChrOffset
sec
sbc #8
; A now holds number of columns that overflow
sta ChrOverflow
; Character ID -> word offset
txa
asl a
tax
; Lookup tile data
lda FontLookup, x
sta TextPointer
lda FontLookup+1, x
sta TextPointer+1
lda #0
sta ChrCurrentRow
; Start of orig row loop
ldy ChrCurrentRow ; 4
.repeat 8, i
lda (TextPointer), y ; 3 * 8 ; get tile data byte for current row
sta WorkingRuneA+i ; 4 * 8
iny ; 2 * 8
.endrepeat
; Shift row to start offset
ldx ChrOffset ; 4
@rightShiftLoop:
cpx #0 ; 2
beq @rightShiftDone ; 2/3
;lsr a
.repeat 8, i
lsr WorkingRuneA+i; 6 * 8
.endrepeat
dex ; 2
jmp @rightShiftLoop ; 3
@rightShiftDone:
; OR onto dest byte
ldx ChrBufferIdx ; 4
.repeat 8, i
lda WorkingRuneA+i ; 4 * 8
ora ChrBuffer+i, x ; 4 * 8
sta ChrBuffer+i, x ; 5 * 8
.endrepeat
lda ChrBufferIdx ; 4
clc ; 2
adc #8 ; 2
sta ChrBufferIdx ; 4
; End of orig row loop
;inc ChrCurrentRow
;ldy ChrCurrentRow
;cpy #8
;bne @rowLoop
; A < 0 Room left on tile
; A == 0 No room, no overflow
; A > 0 Overflow into next tile
lda ChrOverflow
beq @tileEven
cmp #0
bpl @overflow
; Underflow
lda ChrWidth
clc
adc ChrOffset
sta ChrOffset
; Back up the buffer index to the start
; of the previous tile
lda ChrBufferIdx
sec
sbc #8
sta ChrBufferIdx
jmp @loadNext
@tileEven:
lda #0
sta ChrOffset
ldx ChrBufferIdx
.repeat 8, I
sta ChrBuffer+I, x
.endrepeat
@loadNext:
; Move to next letter
inc TextIdx
jmp txt_loadChar_v2
; Second tile
@overflow:
lda #0
sta ChrCurrentRow
; ChrShiftLeft has the number of overflowed
; columns. This needs to be the number of times
; to shift left instead (like the name suggests)
lda #8
sec
sbc ChrOffset
sta ChrShiftLeft
;lda ChrOffset
;eor #$FF
;sta ChrShiftLeft
;@rowOverflow:
ldy ChrCurrentRow
.repeat 8, i
lda (TextPointer), y
sta WorkingRuneA+i
iny
.endrepeat
; Shift the overflow data
ldx ChrShiftLeft
@leftShiftLoop:
cpx #0
beq @leftShiftDone
;asl a
.repeat 8, i
lsr WorkingRuneA+i
.endrepeat
dex
jmp @leftShiftLoop
@leftShiftDone:
ldx ChrBufferIdx
.repeat 8, i
lda WorkingRuneA+i
sta ChrBuffer+i, x
.endrepeat
;inc ChrBufferIdx
lda ChrBufferIdx
clc
adc #8
sta ChrBufferIdx
;inc ChrCurrentRow
;ldy ChrCurrentRow
;cpy #8
;bne @rowOverflow
; Next char's offset
lda ChrWidth
sec
sbc ChrShiftLeft
sta ChrOffset
; Back up a tile
lda ChrBufferIdx
sec
sbc #8
sta ChrBufferIdx
inc TextIdx
jmp txt_loadChar_v2
txt_InsertSpace:
lda #SPACE_WIDTH
sta ChrWidth
clc
adc ChrOffset
sec
sbc #8
cmp #0
bpl @overflow
; Underflow
lda #SPACE_WIDTH
clc
adc ChrOffset
sta ChrOffset
inc TextIdx
jmp txt_loadChar
; Overflow or even
@overflow:
sta ChrOffset
lda ChrBufferIdx
clc
adc #8
sta ChrBufferIdx
inc TextIdx
jmp txt_loadChar
; Prepares a CHR buffer using the text in TextBuffer
TextPrepare:
; Start by clearing the buffer so we don't
; have to do it later (and screw it up).
jsr TextClearBuffer
ldx #0
stx ChrOffset
stx TextIdx
stx ChrBufferIdx
txt_loadChar:
; Load a character from text
ldy TextIdx
ldx TextBuffer, y
beq @exit ; Null terminated name
; Check for end (in characters)
cpy #21 ; Length of the buffer
bcc @noExit
@exit:
lda #$FF
sta ChrBufferReady
rts
@noExit:
cpx #$FF ; check for space
beq txt_InsertSpace
; Get width
lda FontWidths, x
; Find overflow ammount
; Curret offset + character width - 8
sta ChrWidth ; This might not be needed
clc
adc ChrOffset
sec
sbc #8
; A now holds number of columns that overflow
sta ChrOverflow
; Character ID -> word offset
txa
asl a
tax
; Lookup tile data
lda FontLookup, x
sta TextPointer
lda FontLookup+1, x