I am having this weird problem where the sprite is changing randomy and soft locking the game. ClearSprites and AddSprite are both subroutines that I have written myself based on some notes written I wrote based on a conversation I had with Sik. While UpdateSprites is just a modification of LoadSpriteTables. Code: ; ************************************************************* ; ClearSprite ; Clears the sprite counter ; ************************************************************* ClearSprites: move.b #0, (sprite_count) ; set sprite count to 0 rts ; ************************************************************* ; AddSprite ; Adds a sprite to the sprite table and increments counter ; d0 - sprites y position ; d1 - width and height tile bits ; d2 - special (flipping, palette index, priority) ; d3 - tile id ; d4 - sprites x position ; a0 - sprite table ; ************************************************************* AddSprite: move.b (sprite_count), d5 ; sprint count in d5 move.b d5, d6 ; d6 is used to calculate the sprite table offset cmp #80, d5 ; are there too many sprites in the table already? blt SpriteLimitNotReached ; if not branch rts ; return SpriteLimitNotReached: lsl.b #$03, d6 ; calculate sprite table offset (sprite count * sprite size) add.w d6, a0 ; increment address by offset move.w d0, (a0) ; move sprites y position into table addq.l #4, a0 ; increment address by a word move.b d1, (a0) ; move sprites demensions into table addq.l #2, a0 ; increment address by a byte move.b d2, (a0) ; save sprites special bits in table addq.l #2, a0 ; increment address by a byte addq.l #1, d5 ; increment d5(sprite_count) by 1 move.b d5, (a0) ; index of next sprite is d5(sprite_count +1) addq.l #2, a0 ; increment address by a byte move.b d3, (a0) ; save sprites tile id in table addq.l #2, a0 ; increment address by a byte move.w d4, a0 ; save sprites x position in table addq #1, (sprite_count) ; increment sprite counter by 1 rts ; ************************************************************* ; Updates and draws the sprite table ; ************************************************************* UpdateSprites: lea (spritelist_table), a0 ; sprite table in a0 move.b (sprite_count), d0 ; load sprite counter into d0 and.l #0x000000FF, d0 mulu.w #SizeSpriteDesc, d0 ; Offset into sprite table swap d0 ; To upper word or.l #vdp_write_sprite_table, d0 ; Add to write address move.l d0, vdp_control ; Set read address move.l (a0)+, vdp_data ; 8 bytes of data move.l (a0)+, vdp_data rts Code: LoadSpriteTables: ; a0 --- Sprite data address ; d0 (b) Number of sprites move.l #vdp_write_sprite_table, vdp_control and.l #0x000000FF, d0 subq.b #0x1, d0 ; Minus 1 for counter @AttrCopy: move.l (a0)+, vdp_data ; 8 bytes of data move.l (a0)+, vdp_data dbra d0, @AttrCopy rts Notes: Code: OK so you want an arbitrary number of sprites 1) Reserve 640 bytes in RAM for a table *Complete* 2) Make a ClearSprites function that sets the sprite count to 0 *Complete?* 3) Make an AddSprite function that inserts a sprite into the table (may want to check that there aren't too many sprites, i.e. 80) 4) Make an UpdateSprites function that loads the table to VRAM :P Incrementing a0 addq.l #1, a0 Replace #1 with a value from 1 to 8 Or replace addq with add if you need a larger value :v Storing offset to a0 lea (a0,d5.w), a0 -or- add.w d5, a0 Pick either Both do the job here Then every frame: 1) Call ClearSprites at the beginning 2) Call AddSprite for every sprite you want to draw 3) Call UpdateSprites at the end You don't need to keep track of sprites once added. Also if you do run into the limit (80 sprites), huuuuh, I'd say to just drop the excess sprites (i.e. just return without adding them) Here is a link to the ROM in case you wanna see what i mean. Sincerely, Scorpion Illuminati
