Managed to make it print text xD

compile.bat

@@ -1,5 +1,7 @@
 @ECHO off
 
+:begin
+
 ECHO.
 ECHO Compiling main.asm
 ECHO rgbasm -o main.o main.asm
@@ -14,9 +16,9 @@ IF %ERRORLEVEL% NEQ 0 (
 
 ECHO.
 ECHO Linking main.o
-ECHO rgblink -o test.gb main.o
+ECHO rgblink -o test.gb -m test.map -n test.sym main.o
 
-C:\Users\jonatan.SAMSYN\Documents\gb\tools\compiler\rgblink -o test.gb main.o
+C:\Users\jonatan.SAMSYN\Documents\gb\tools\compiler\rgblink -o test.gb -m test.map -n test.sym main.o
 
 IF %ERRORLEVEL% NEQ 0 (
   ECHO.
@@ -43,3 +45,5 @@ ECHO DONE
 :eof
 ECHO.
 PAUSE
+
+GOTO begin

game/game.asm

@@ -1,14 +1,22 @@
-INCLUDE "game/string.asm"
+INCLUDE "game/text.asm"
 
 SECTION "Game Loop", ROM0
 
 GameLoop:
-    ld b, 0
+.wait
-    ld c, 0
-    ld hl, HelloWorldStr
-    call PrintString
-.lockup
     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, .lockup ; Jump back to waitVBlank if rLY is less than 144
+    jr c, .wait ; Jump back to waitVBlank if rLY is less than 144
-    jr .lockup
+
+    ld de, HelloWorldStr
+    call StartText
+.mainloop
+    ; Start our game loop
+    call DrawActiveText
+    call WaitVBlank
+    jr .mainloop
+
+Section "Hello wrold string", ROM0
+
+HelloWorldStr:
+    db "Hello, Worl'd.!?", 0

game/string.asm

@@ -1,25 +0,0 @@
-SECTION "String code", ROM0
-; Print String on screen
-; @param b - PosX on where to draw text
-; @param c - PosY on where to draw text
-; @param hl - Address source string
-; @return a
-; @return b
-; @return c
-; @return de - Destination memory in map
-; @return hl = Address Target to the byte after the last byte on the target (garbage)
-PrintString:
-    ld de, $9800
-.start
-    ld a, [hl] ; Load the first byte in the string
-    inc hl ; Increment immediately to next space
-    ld [dei], a
-    and a
-    jr nz, .start
-    ret
-.render
-.finish
-    inc b
-    cp b, 14
-    
-

game/text.asm

@@ -0,0 +1,190 @@
+SECTION "ram_textwriter", WRAM0
+textwriter_curtext: ds 2
+textwriter_curletter: ds 1
+textwriter_posx: ds 1
+textwriter_posy: ds 1
+textwriter_curdelay: ds 1
+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
+    ;   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
+    ;   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
+    ;   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
+    ;   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
+    ;   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
+    ;   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
+    ;   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
+
+SECTION "TextWriter", ROM0
+
+; Start to print a 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 - 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
+StartText:
+    ld a, 0
+    ld [textwriter_curletter], a
+    ld [textwriter_curdelay], a
+    ld a, 1
+    ld [textwriter_active], a
+    ld [textwriter_posx], a
+    ld [textwriter_posy], a
+    ld hl, textwriter_curtext
+    ld a, d
+    ld [hli], a
+    ld a, e
+    ld [hl], a
+    dec hl
+    ret
+
+; Draw text if one is currently active
+; @return a - 0 if not active, 1 if active
+DrawActiveText:
+    ld a, [textwriter_active] ; Check if text is currently active
+    and a
+    jr z, .exit
+
+    ; Delay writing a letter by 10 frames
+    ld a, [textwriter_curdelay]
+    inc a
+    ld [textwriter_curdelay], a
+    cp 20
+    jr c, .exit
+
+    ; Reset the curdelay
+    ld a, 0
+    ld [textwriter_curdelay], a
+
+    ; 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
+    ld d, [hl] ; Store the first byte address to d
+    inc hl ; Move to next byte
+    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 a, [textwriter_posy]
+    ld c, a
+    ld a, [textwriter_posx]
+    ld b, a
+.moveyaxis
+    ; 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, .movexaxis ; 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, h ; Grab the second part of the address
+    adc a, $00 ; Add only the accumilator
+    ld h, a ; Store the position back
+    dec c ; Decrement our y parameter
+    jr .moveyaxis ; Repeat
+.movexaxis
+    ; 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, .drawletter ; Jump to drawletter 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 .movexaxis ; Repeat
+.drawletter
+    ld a, [de] ; Load the first byte in the string
+    ld bc, textwriter_map
+    ld c, a
+    ld a, [bc]
+    ld [hl], a ; Print the character byte directly onto the map
+
+    ld a, [de]
+    and a ; Check if we reached the end
+    jr nz, .continue
+    ; We have reached the end of the string, disable textwriter
+    ld a, 0
+    ld [textwriter_active], a
+.continue
+    ; Time to update our work ram
+    ; Load the position pointer of current text to next letter
+    ld hl, textwriter_curtext
+    inc de ; Increment to next letter in string
+    ld a, d
+    ld [hli], a
+    ld a, e
+    ld [hl], a
+    ; Update the x position in ram
+    ld a, [textwriter_posx]
+    inc a
+    ld [textwriter_posx], a
+    ; Update the current letter being drawn in ram
+    ld a, [textwriter_curletter]
+    inc a
+    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

@@ -2,10 +2,21 @@ INCLUDE "hardware.inc"
 INCLUDE "game/game.asm"
 INCLUDE "tools.asm"
 
+SECTION "InterruptVblank", ROM0[$0040]
+    reti
+SECTION "InterruptLCDC", ROM0[$0048]
+    reti
+SECTION "InterruptTimer_Overflow", ROM0[$0050]
+    reti
+SECTION "InterruptSerial", ROM0[$0058]
+    reti
+SECTION "Interruptp1thru4", ROM0[$0060]
+    reti
+
 SECTION "Header", ROM0[$100]
 
 EntryPoint: ;
-    di ; Disable interrupts. That way we can avoid dealing with them, especially since we didn't talk about them yet
+    ei ; Simple nop ; di ; Disable interrupts for now
     jp Start ; Leave this tiny space
 
 REPT $150 - $104
@@ -21,9 +32,9 @@ Start:
 
     ; Turn off the LCD
 .waitVBlank
-    ld a, [rLY] ; Load the current vertical line being rendered
+    ld a, $01
-    cp 144 ; Check if we're past VBlank (1 to 144 = carry bit set)
+    ld [$FFFF], a ; Force enable VBLANK Interrupt
-    jr c, .waitVBlank ; Jump back to waitVBlank if rLY is less than 144
+    halt
 
     xor a ; ld a, 0 ; Reset the accumilator register
     ; Our target is to set bit 7 reset on the LDC to turn it off
@@ -31,21 +42,11 @@ Start:
 
 ; ----------- Font Begin copying to VRAM -----------
     ; Start copying our font to vram
-    ld de, FontTiles ; The start of the font tiles
+    ld de, Page1 ; The start of the font tiles
     ld hl, $9000 ; Set registers hl to $9000 which is the beginning of vram
-    ld bc, FontTilesEnd - FontTiles ; The total length of font tiles
+    ld bc, Page1End - Page1 ; The total length of font tiles
     call Memcpy
 
-; ----------- Begin copying string to palette -----------
-    ld hl, $9800 ; This will print the string at the top-left corner of screen
-    ld de, HelloWorldStr
-.copyString
-    ld a, [de] ; Read the first byte in the string to accumilator
-    ld [hli], a ; Write the byte from the accumilator to the destination while incrementing destination address
-    inc de ; Move to next byte in string
-    and a ; AND a with A, Checking if we copied a zero (end of string)
-    jr nz, .copyString ; Continue copying while not zero
-
 ; ----------- Start the display -----------
     ; Init the display register
     ld a, %11100100 ; Load the palette of white, light gray, dark gray, black
@@ -59,17 +60,15 @@ Start:
     ld [rNR52], a ; Turn off sound
 
     ; Turn the screen on, display background
-    ld a, %10000001 ; screen on = 8th bit, background display = 1st bit
+    ld a, LCDCF_ON|LCDCF_BGON
+    ; ld a, %10000001 ; screen on = 8th bit, background display = 1st bit
     ld [rLCDC], a ; Set the screen flags
+    ei ; Enable interrupts again?
     jp GameLoop
 
 SECTION "Font", ROM0
 
-FontTiles:
+Page1:
-INCBIN "font.chr"
+INCBIN "assets/page1.chr"
-FontTilesEnd:
+Page1End:
 
-Section "Hello wrold string", ROM0
-
-HelloWorldStr:
-    db "Hello World!", 0

test.map

@@ -0,0 +1,128 @@
+ROM Bank #0 (HOME):
+  SECTION: $0200-$027F ($0080 bytes) ["ram_textmap"]
+           $0200 = textwriter_map
+  SECTION: $0150-$01F5 ($00A6 bytes) ["TextWriter"]
+           $01D0 = DrawActiveText.exit
+           $01A2 = DrawActiveText.movexaxis
+           $0193 = DrawActiveText.moveyaxis
+           $01AA = DrawActiveText.drawletter
+           $01BA = DrawActiveText.continue
+           $01E6 = PrintString.movexaxis2
+           $01D7 = PrintString.moveyaxis2
+           $01EE = PrintString.start2
+           $0150 = StartText
+           $016C = DrawActiveText
+  SECTION: $0061-$0074 ($0014 bytes) ["Game Loop"]
+           $0061 = GameLoop.wait
+           $006D = GameLoop.mainloop
+           $0061 = GameLoop
+  SECTION: $0075-$0085 ($0011 bytes) ["Hello wrold string"]
+           $0075 = HelloWorldStr
+  SECTION: $0031-$003C ($000C bytes) ["Tools"]
+           $003A = WaitVBlank
+           $0031 = Memcpy
+  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"]
+           $0000 = Start
+           $0000 = Start.waitVBlank
+  SECTION: $0280-$127F ($1000 bytes) ["Font"]
+           $0280 = Page1
+           $1280 = Page1End
+    SLACK: $2E23 bytes
+
+WRAM Bank #0:
+  SECTION: $C000-$C006 ($0007 bytes) ["ram_textwriter"]
+           $C002 = textwriter_curletter
+           $C005 = textwriter_curdelay
+           $C006 = textwriter_active
+           $C003 = textwriter_posx
+           $C004 = textwriter_posy
+           $C000 = textwriter_curtext
+    SLACK: $0FF9 bytes
+
+WRAM Bank #1:
+  EMPTY
+
+WRAM Bank #2:
+  EMPTY
+
+WRAM Bank #3:
+  EMPTY
+
+WRAM Bank #4:
+  EMPTY
+
+WRAM Bank #5:
+  EMPTY
+
+WRAM Bank #6:
+  EMPTY
+
+WRAM Bank #7:
+  EMPTY
+
+VRAM Bank #0:
+  EMPTY
+
+VRAM Bank #1:
+  EMPTY
+
+OAM:
+  EMPTY
+
+HRAM:
+  EMPTY
+
+SRAM Bank #0:
+  EMPTY
+
+SRAM Bank #1:
+  EMPTY
+
+SRAM Bank #2:
+  EMPTY
+
+SRAM Bank #3:
+  EMPTY
+
+SRAM Bank #4:
+  EMPTY
+
+SRAM Bank #5:
+  EMPTY
+
+SRAM Bank #6:
+  EMPTY
+
+SRAM Bank #7:
+  EMPTY
+
+SRAM Bank #8:
+  EMPTY
+
+SRAM Bank #9:
+  EMPTY
+
+SRAM Bank #10:
+  EMPTY
+
+SRAM Bank #11:
+  EMPTY
+
+SRAM Bank #12:
+  EMPTY
+
+SRAM Bank #13:
+  EMPTY
+
+SRAM Bank #14:
+  EMPTY
+
+SRAM Bank #15:
+  EMPTY
+

test.sym

@@ -0,0 +1,29 @@
+; File generated by rgblink
+
+00:0200 textwriter_map
+00:01D0 DrawActiveText.exit
+00:01A2 DrawActiveText.movexaxis
+00:0193 DrawActiveText.moveyaxis
+00:01AA DrawActiveText.drawletter
+00:01BA DrawActiveText.continue
+00:01E6 PrintString.movexaxis2
+00:01D7 PrintString.moveyaxis2
+00:01EE PrintString.start2
+00:0150 StartText
+00:016C DrawActiveText
+00:0061 GameLoop.wait
+00:006D GameLoop.mainloop
+00:0061 GameLoop
+00:0075 HelloWorldStr
+00:003A WaitVBlank
+00:0031 Memcpy
+00:0000 Start
+00:0000 Start.waitVBlank
+00:0280 Page1
+00:1280 Page1End
+00:C002 textwriter_curletter
+00:C005 textwriter_curdelay
+00:C006 textwriter_active
+00:C003 textwriter_posx
+00:C004 textwriter_posy
+00:C000 textwriter_curtext

tools.asm

@@ -17,3 +17,13 @@ Memcpy:
     or c ; OR together the second half of total amount with the first half
     jr nz, Memcpy ; Loop back to Memcpy if not zero
     ret
+
+
+;;
+; Waits for the vblank ISR to increment the count of vertical blanks.
+; Will lock up if DI, vblank IRQ off, or LCD off.
+; Clobbers A, HL
+WaitVBlank:
+.wait
+    halt
+    ret