Displaying text

ASM routine for displaying text with a 8x8 pixel font on the fix layer:

Write8Text: move.w d1,VRAM_ADDR move.w #$20,VRAM_MOD clr.w  d0 textmaplp: move.b (a0)+,d0 tst.b  d0    beq     textmapend cmp.b  #$FF,d0 bne    nolinejump addq.w #1,d1 move.w d1,VRAM_ADDR bra    textmaplp nolinejump: addq.w ASCIISTART,d0 move.w d0,VRAM_RW bra    textmaplp textmapend: rts
 * Displays text pointed by A0 at the VRAM address in D1. $FF:Next line, $00:End of text.
 * Uses A0, D0 and REG_VRAMMOD

"ASCIISTART" should be the fix tile number corresponding to ASCII value 0. This depends on what tileset you are using. Usually, onboard fix tilesets have a full 8x8 font starting at tile #0.

The VRAM address is calculated from the desired text position: D1=#FIXMAP+(Y+2+((X+1)*32)) "FIXMAP" being #$7000.