diff options
Diffstat (limited to 'src-68k/video')
| -rw-r--r-- | src-68k/video/bg.68k | 43 | ||||
| -rw-r--r-- | src-68k/video/text.68k | 108 | ||||
| -rw-r--r-- | src-68k/video/vsync.68k | 19 |
3 files changed, 170 insertions, 0 deletions
diff --git a/src-68k/video/bg.68k b/src-68k/video/bg.68k new file mode 100644 index 0000000..c64e287 --- /dev/null +++ b/src-68k/video/bg.68k @@ -0,0 +1,43 @@ +;**************************************************************************** +; DrawBG +; Draws the background +;**************************************************************************** + +DrawBG: + lea ($C00004), a2 + lea ($C00000), a1 + + lea (@BGData), a0 + move.l #$60000003, d0 + moveq #28-1, d6 +@YLoop: + move.l d0, (a2) + moveq #40-1, d7 +@XLoop: + move.w (a0)+, (a1) + dbf d7, @XLoop + add.l #$00800000, d0 + dbf d6, @YLoop + + lea (@BGData), a0 + move.l #$60000002, d0 + moveq #28-1, d6 +@YLoop2: + move.l d0, (a2) + moveq #40-1, d7 +@XLoop2: + move.w (a0)+, d1 + bset.l #11, d1 + move.w d1, (a1) + dbf d7, @XLoop2 + add.l #$00800000, d0 + dbf d6, @YLoop2 + + rts ; End of subroutine + +;**************************************************************************** +; Background data +;**************************************************************************** + +@BGData: + incbin "data/bg.bin" diff --git a/src-68k/video/text.68k b/src-68k/video/text.68k new file mode 100644 index 0000000..832605e --- /dev/null +++ b/src-68k/video/text.68k @@ -0,0 +1,108 @@ +;**************************************************************************** +; LoadFont +; Loads the font in VRAM +;**************************************************************************** + +LoadFont: + move.l #$40000000, ($C00004) ; Where font will be stored + + lea (@Font), a0 ; Font data + lea ($C00000), a1 ; VDP data port + move.w #96*16-1, d7 ; Go through all lines +@Loop: + + move.b (a0)+, d0 ; Fetch next line + moveq #0, d1 ; Initial color + moveq #8-1, d6 ; Go through all pixels +@ILoop: + + add.b d0, d0 ; Get pixel color + bcc.s @Transparent + moveq #3, d1 +@Transparent: + subq.b #1, d1 + bgt.s @NoUnderflow + moveq #0, d1 +@NoUnderflow: + + lsl.l #4, d2 ; Make room for pixel + or.b d1, d2 ; Store pixel + dbf d6, @ILoop ; Next pixel + + move.l d2, (a1) ; Store line in VRAM + dbf d7, @Loop ; Next line + + rts ; End of subroutine + +@Font: + incbin "data/font.bin" + +;**************************************************************************** +; WriteString +; Writes a string on screen +; +; input d0.w ... X coordinate +; input d1.w ... Y coordinate +; input d2.w ... FX and such +; input a0.l ... String +;**************************************************************************** + +WriteString: + movem.l d0-d2, -(sp) ; Save registers + + lsl.w #6, d1 ; Calculate address + add.w d1, d0 + add.w d0, d0 + + and.l #$FFFF, d0 ; Tell VDP the address + or.l #$00034000, d0 + swap d0 + move.l d0, ($C00004) + + lea ($C00000), a5 ; VDP data port + moveq #2-1, d7 ; Go through both lines +@Loop: + + move.l a0, a6 +@ILoop: + move.b (a6)+, d1 ; Get next character + beq.s @End ; End of string? + + sub.b #$20, d1 ; Write tile in VRAM + and.w #$7F, d1 + add.w d1, d1 + add.w d2, d1 + move.w d1, (a5) + + bra.s @ILoop ; Next character + +@End: + add.l #$80<<16, d0 + move.l d0, ($C00004) + addq.w #1, d2 ; Next line + dbf d7, @Loop + + movem.l (sp)+, d0-d2 ; Restore registers + rts ; End of subroutine + +;**************************************************************************** +; ClearLines +; Clears the description lines +;**************************************************************************** + +ClearLines: + move.l #$448E0003, d0 ; Initial position to clear + lea ($C00004), a0 ; VDP control port + lea ($C00000), a1 ; VDP data port + + moveq #7-1, d1 ; Clear all lines + moveq #0, d2 +@Loop: + move.l d0, (a0) + rept 26/2 + move.l d2, (a1) + endr + add.l #$80<<16, d0 + dbf d1, @Loop + + rts ; End of subroutine diff --git a/src-68k/video/vsync.68k b/src-68k/video/vsync.68k new file mode 100644 index 0000000..ed5ac17 --- /dev/null +++ b/src-68k/video/vsync.68k @@ -0,0 +1,19 @@ +;**************************************************************************** +; VSync +; Waits until the next frame +;**************************************************************************** + +VSync: + lea ($C00004), a6 + +@Loop1: ; Wait until current VBlank is over + move.w (a6), d7 + btst.l #3, d7 + bne.s @Loop1 + +@Loop2: ; Wait until next VBlank starts + move.w (a6), d7 + btst.l #3, d7 + beq.s @Loop2 + + rts ; End of subroutine |