Updated text renderer a bit

game/game.asm

@@ -3,11 +3,6 @@ INCLUDE "game/text.asm"
 SECTION "Game Loop", ROM0
 
 GameLoop:
-.wait
-    ld a, [rLY] ; Load the current vertical line being rendered
-    cp 144 ; Check if we're past VBlank (1 to 144 = carry bit set)
-    jr c, .wait ; Jump back to waitVBlank if rLY is less than 144
-
     ld de, HelloWorldStr
     call StartText
 .mainloop
@@ -19,4 +14,6 @@ GameLoop:
 Section "Hello wrold string", ROM0
 
 HelloWorldStr:
-    db "Hello, Worl'd.!?", 0
+    ;  [                  ]
+    db "...wake up...\n"
+    db "please wake up...", 0

game/text.asm

@@ -9,24 +9,62 @@ textwriter_active: ds 1
 SECTION "ram_textmap", ROM0,ALIGN[8]
 textwriter_map:
     ;   00  01  02  03  04  05  06  07  08  09  0A  0B  0C  0D  0E  0F
-    db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00 ; 0
+    db $50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50 ; 0
     ;   10  11  12  13  14  15  16  17  18  19  1A  1B  1C  1D  1E  1F
-    db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00 ; 16
+    db $50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50 ; 16
     ;   20  21  22  23  24  25  26  27  28  29  2A  2B  2C  2D  2E  2F
-    db $00,$41,$00,$00,$00,$00,$00,$43,$00,$00,$00,$00,$42,$00,$3F,$00 ; 32
+    db $50,$41,$50,$50,$50,$50,$50,$43,$50,$50,$50,$50,$42,$50,$3F,$50 ; 32
     ;   30  31  32  33  34  35  36  37  38  39  3A  3B  3C  3D  3E  3F
-    db $35,$36,$37,$38,$39,$3A,$3B,$3C,$3D,$3E,$00,$00,$00,$00,$00,$40 ; 48
+    db $35,$36,$37,$38,$39,$3A,$3B,$3C,$3D,$3E,$50,$50,$50,$50,$50,$40 ; 48
     ;   40  41  42  43  44  45  46  47  48  49  4A  4B  4C  4D  4E  4F
-    db $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0E,$0F ; 64
+    db $50,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0E,$0F ; 64
     ;   50  51  52  53  54  55  56  57  58  59  5A  5B  5C  5D  5E  5F
-    db $10,$11,$12,$13,$14,$15,$16,$17,$18,$19,$1A,$00,$00,$00,$00,$00 ; 80
+    db $10,$11,$12,$13,$14,$15,$16,$17,$18,$19,$1A,$50,$50,$50,$50,$50 ; 80
     ;   60  61  62  63  64  65  66  67  68  69  6A  6B  6C  6D  6E  6F
-    db $00,$1B,$1C,$1D,$1E,$1F,$20,$21,$22,$23,$24,$25,$26,$27,$28,$29 ; 96
+    db $50,$1B,$1C,$1D,$1E,$1F,$20,$21,$22,$23,$24,$25,$26,$27,$28,$29 ; 96
     ;   70  71  72  73  74  75  76  77  78  79  7A  7B  7C  7D  7E  7F
-    db $2A,$2B,$2C,$2D,$2E,$2F,$30,$31,$32,$33,$34,$00,$00,$00,$00,$00 ; 112
+    db $2A,$2B,$2C,$2D,$2E,$2F,$30,$31,$32,$33,$34,$50,$50,$50,$50,$50 ; 112
 
 SECTION "TextWriter", ROM0
 
+InitWindow:
+    ; Fill first line in window with straight line
+    ld hl, _SCRN1
+    ld b, $20
+    ld a, $52
+    call Memfill
+    ; Fill rest of the area with dark bg
+    ld b, $40
+    ld a, $50
+    call Memfill
+    ; Fill last line in window with straight line
+    ld b, $20
+    ld a, $57
+    call Memfill
+    ; Top left corner
+    ld hl, _SCRN1
+    ld [hl], $51
+    ; Top right corner
+    ld hl, _SCRN1 + 19
+    ld [hl], $53
+    ; Bottom Left corner
+    ld hl, _SCRN1 + $60
+    ld [hl], $56
+    ; Bottom Right corner
+    ld hl, _SCRN1 + $60 + 19
+    ld [hl], $58
+    ; Left line
+    ld hl, _SCRN1 + $20
+    ld [hl], $54
+    ld hl, _SCRN1 + $40
+    ld [hl], $54
+    ; Right line
+    ld hl, _SCRN1 + $20 + 19
+    ld [hl], $55
+    ld hl, _SCRN1 + $40 + 19
+    ld [hl], $55
+    ret ; Return
+
 ; Start to print a string on screen
 ; @param b - PosX on where to draw text
 ; @param c - PosY on where to draw text
@@ -57,19 +95,20 @@ StartText:
 DrawActiveText:
     ld a, [textwriter_active] ; Check if text is currently active
     and a
-    jr z, .exit
+    jp z, .exit
 
     ; Delay writing a letter by 10 frames
     ld a, [textwriter_curdelay]
     inc a
     ld [textwriter_curdelay], a
-    cp 20
+    cp 10
     jr c, .exit
 
     ; Reset the curdelay
     ld a, 0
     ld [textwriter_curdelay], a
 
+.startdrawtext
     ; Get the memory address pointing to the text currently being
     ; displayed. This is stored in textwriter_curtext
     ld hl, textwriter_curtext ; Get the memory address of the pointer
@@ -78,7 +117,7 @@ DrawActiveText:
     ld e, [hl] ; Store the next byte address to e
     ; We now have the current letter being drawn at [de]
 
-    ld hl, _SCRN0 ; Load the top-left map position to our map
+    ld hl, _SCRN1 ; Load the top-left map position to our map
     ld a, [textwriter_posy]
     ld c, a
     ld a, [textwriter_posx]
@@ -108,22 +147,54 @@ DrawActiveText:
     jr .movexaxis ; Repeat
 .drawletter
     ld a, [de] ; Load the first byte in the string
-    ld bc, textwriter_map
+    ld bc, textwriter_map ; Get the map for the ASCII->Tile map
-    ld c, a
+    ld c, a ; Set the position of C to the ASCII byte of current character
-    ld a, [bc]
+    ld a, [bc] ; Get the tile byte for the ASCII from the map
-    ld [hl], a ; Print the character byte directly onto the map
+    ld [hl], a ; Print the byte to the map
 
     ld a, [de]
     and a ; Check if we reached the end
-    jr nz, .continue
+    jr nz, .checkNewline
+
     ; We have reached the end of the string, disable textwriter
+    ld b, 0 ; Disable repeater
     ld a, 0
     ld [textwriter_active], a
+    jr .continue ; Jump straight to continue. No need to check anything
+
+.checkNewline
+    ld a, [de] ; Regrab the ascii byte we printed
+    cp a, $0A ; Check if it was a new line
+    jr nz, .checkRepeatOnce ; Jump to checkRepeatOnce if it wasn't a new line
+
+    ; The byte we printed was a new line so we increment Y position
+    ; and reset our X position.
+    ld a, 0 ; Usually we'd print into first position but since we're jumping
+            ; into continue, continue will automatically increment x for us.
+    ld [textwriter_posx], a
+    ld a, [textwriter_posy]
+    inc a
+    ld [textwriter_posy], a
+
+    ; We already know we printed empty character so we can skip checking
+    ; if we need to repeat once again and just set the b flag
+    ld b, 1
+    jr .continue
+
+.checkRepeatOnce
+    ld a, [bc] ; Regrab the tile we printer
+    ld b, 0 ; Use b as our marker if we should repeat once
+
+    ; Check if we printed an empty letter
+    cp a, $50
+    jr nz, .continue
+    ld b, 1
+
 .continue
     ; Time to update our work ram
-    ; Load the position pointer of current text to next letter
+    inc de ; Increment de to next letter
+    ; Load the position pointer of current text and update it to the next letter
     ld hl, textwriter_curtext
-    inc de ; Increment to next letter in string
     ld a, d
     ld [hli], a
     ld a, e
@@ -135,56 +206,15 @@ DrawActiveText:
     ; Update the current letter being drawn in ram
     ld a, [textwriter_curletter]
     inc a
+
+    ; Check if we need to repeat whole thing due to printing empty character
+    ld a, b
+    and b
+    jr nz, .startdrawtext
+
+    ; We didn't print an empty
     ld [textwriter_curletter], a
 
 .exit
     ld a, [textwriter_active]
     ret
-
-
-; Print String on screen
-; @param b - PosX on where to draw text
-; @param c - PosY on where to draw text
-; @param de - Address source string
-; @return a
-; @return b
-; @return c
-; @return hl - Destination memory in map
-; @return hl = Address Target to the byte after the last byte on the target (garbage)
-PrintString:
-    ld hl, _SCRN0 ; Load the top-left map position to our map
-.moveyaxis2
-    ; Our first objective is to position the text to correct position
-    ; We do so shifting the position by $20 for each y axis
-    ; and position by $01 for each x axis that needs movement
-    ld a, c ; Load the y position to our accumilator
-    and a ; Check if it's zero
-    jr z, .movexaxis2 ; Jump to x axis if it's zero and no moving necessary
-    ld a, l ; Load the first half of the destination position
-    add a, $20 ; Add $20 (one vertical line)
-    ld l, a ; Store the position back 
-    ld a, b ; Grab the second part of the address
-    adc a, $00 ; Add only the accumilator
-    ld b, a ; Store the position back
-    dec c ; Decrement our y parameter
-    jr .moveyaxis2 ; Repeat
-.movexaxis2
-    ; Now we check and move the position based on the x position
-    ld a, b ; Load the x position to our accimulator
-    and a ; Check if it's zero
-    jr z, .start2 ; Jump to start2 if it's zero already
-    inc hl ; Increment the map position by one since we need to move by x position
-    dec b ; Decrement our x parameter
-    jr .movexaxis2 ; Repeat
-.start2
-    ld a, [de] ; Load the first byte in the string
-    ld [hl], a ; Write the byte from the accumilator to the destination address
-               ; Also increment destination by one.
-               ; This effectively prints the character byte in accumilator
-    inc de ; Increment to next byte in string
-    inc hl
-    and a ; And together a with itself. This sets the flag
-    jr nz, .start2 ; Go back to start if we didn't just copy a zero.
-    ret
-    
-

main.asm

@@ -59,11 +59,26 @@ Start:
 
     ld [rNR52], a ; Turn off sound
 
+    ld a, 7
+    ld [rWX], a
+    ld a, (SCRN_Y - 32)
+    ld [rWY], a
+
+    ; Reset OAM memory with zeros
+    ld hl, _OAMRAM ; Set position of OAM Ram to hl
+    ld a, 0 ; Fill that memory space with zero
+    ld b, $FEA0 - _OAMRAM ; Get the full size of the fill
+    call Memfill
+
+    ; Initialize other stuff
+    call InitWindow
+
     ; Turn the screen on, display background
-    ld a, LCDCF_ON|LCDCF_BGON
+    ld a, LCDCF_ON|LCDCF_BGON|LCDCF_WINON|LCDCF_WIN9C00
-    ; ld a, %10000001 ; screen on = 8th bit, background display = 1st bit
     ld [rLCDC], a ; Set the screen flags
-    ei ; Enable interrupts again?
+
+    call WaitVBlank
+
     jp GameLoop
 
 SECTION "Font", ROM0

test.map

@@ -1,39 +1,40 @@
 ROM Bank #0 (HOME):
   SECTION: $0200-$027F ($0080 bytes) ["ram_textmap"]
            $0200 = textwriter_map
-  SECTION: $0150-$01F5 ($00A6 bytes) ["TextWriter"]
+  SECTION: $1280-$136B ($00EC bytes) ["TextWriter"]
-           $01D0 = DrawActiveText.exit
+           $1368 = DrawActiveText.exit
-           $01A2 = DrawActiveText.movexaxis
+           $1314 = DrawActiveText.movexaxis
-           $0193 = DrawActiveText.moveyaxis
+           $1305 = DrawActiveText.moveyaxis
-           $01AA = DrawActiveText.drawletter
+           $131C = DrawActiveText.drawletter
-           $01BA = DrawActiveText.continue
+           $1330 = DrawActiveText.checkNewline
-           $01E6 = PrintString.movexaxis2
+           $134E = DrawActiveText.continue
-           $01D7 = PrintString.moveyaxis2
+           $1345 = DrawActiveText.checkRepeatOnce
-           $01EE = PrintString.start2
+           $12F4 = DrawActiveText.startdrawtext
-           $0150 = StartText
+           $12C1 = StartText
-           $016C = DrawActiveText
+           $12DD = DrawActiveText
-  SECTION: $0061-$0074 ($0014 bytes) ["Game Loop"]
+           $1280 = InitWindow
-           $0061 = GameLoop.wait
+  SECTION: $0031-$003E ($000E bytes) ["Game Loop"]
-           $006D = GameLoop.mainloop
+           $0037 = GameLoop.mainloop
-           $0061 = GameLoop
+           $0031 = GameLoop
-  SECTION: $0075-$0085 ($0011 bytes) ["Hello wrold string"]
+  SECTION: $0000-$001F ($0020 bytes) ["Hello wrold string"]
-           $0075 = HelloWorldStr
+           $0000 = HelloWorldStr
-  SECTION: $0031-$003C ($000C bytes) ["Tools"]
+  SECTION: $0020-$0030 ($0011 bytes) ["Tools"]
-           $003A = WaitVBlank
+           $0029 = Memfill
-           $0031 = Memcpy
+           $002E = WaitVBlank
+           $0020 = Memcpy
+           $0029 = Memfill.repeatFill
   SECTION: $0040-$0040 ($0001 bytes) ["InterruptVblank"]
   SECTION: $0048-$0048 ($0001 bytes) ["InterruptLCDC"]
   SECTION: $0050-$0050 ($0001 bytes) ["InterruptTimer_Overflow"]
   SECTION: $0058-$0058 ($0001 bytes) ["InterruptSerial"]
   SECTION: $0060-$0060 ($0001 bytes) ["Interruptp1thru4"]
   SECTION: $0100-$014F ($0050 bytes) ["Header"]
-  SECTION: $0000-$0030 ($0031 bytes) ["Intro code"]
+  SECTION: $0061-$00A1 ($0041 bytes) ["Intro code"]
-           $0000 = Start
+           $0061 = Start
-           $0000 = Start.waitVBlank
   SECTION: $0280-$127F ($1000 bytes) ["Font"]
            $0280 = Page1
            $1280 = Page1End
-    SLACK: $2E23 bytes
+    SLACK: $2DBF bytes
 
 WRAM Bank #0:
   SECTION: $C000-$C006 ($0007 bytes) ["ram_textwriter"]

test.sym

@@ -1,24 +1,25 @@
 ; File generated by rgblink
 
 00:0200 textwriter_map
-00:01D0 DrawActiveText.exit
+00:1368 DrawActiveText.exit
-00:01A2 DrawActiveText.movexaxis
+00:1314 DrawActiveText.movexaxis
-00:0193 DrawActiveText.moveyaxis
+00:1305 DrawActiveText.moveyaxis
-00:01AA DrawActiveText.drawletter
+00:131C DrawActiveText.drawletter
-00:01BA DrawActiveText.continue
+00:1330 DrawActiveText.checkNewline
-00:01E6 PrintString.movexaxis2
+00:134E DrawActiveText.continue
-00:01D7 PrintString.moveyaxis2
+00:1345 DrawActiveText.checkRepeatOnce
-00:01EE PrintString.start2
+00:12F4 DrawActiveText.startdrawtext
-00:0150 StartText
+00:12C1 StartText
-00:016C DrawActiveText
+00:12DD DrawActiveText
-00:0061 GameLoop.wait
+00:1280 InitWindow
-00:006D GameLoop.mainloop
+00:0037 GameLoop.mainloop
-00:0061 GameLoop
+00:0031 GameLoop
-00:0075 HelloWorldStr
+00:0000 HelloWorldStr
-00:003A WaitVBlank
+00:0029 Memfill
-00:0031 Memcpy
+00:002E WaitVBlank
-00:0000 Start
+00:0020 Memcpy
-00:0000 Start.waitVBlank
+00:0029 Memfill.repeatFill
+00:0061 Start
 00:0280 Page1
 00:1280 Page1End
 00:C002 textwriter_curletter

tools.asm

@@ -18,6 +18,22 @@ Memcpy:
     jr nz, Memcpy ; Loop back to Memcpy if not zero
     ret
 
+Memfill:
+; Fill an area in memory at position hl with value a for b amount of times
+; 
+; @param hl - Starting address in memory to fill
+; @param a - The value to fill said address space with
+; @param b - How many bytes we should fill starting from said address space
+; @return a - garbage
+; @return b - PosX on where to draw text
+; @return c - PosY on where to draw text
+; @return hl - Workram position for text pointer
+; @return de - Memory address to source string
+.repeatFill
+    ld [hli], a
+    dec b
+    jr nz, .repeatFill
+    ret
 
 ;;
 ; Waits for the vblank ISR to increment the count of vertical blanks.