diff options
| -rw-r--r-- | src/example/nes.asm | 119 | ||||
| -rwxr-xr-x | src/example/tiles.chr | bin | 0 -> 4096 bytes |
2 files changed, 68 insertions, 51 deletions
diff --git a/src/example/nes.asm b/src/example/nes.asm index 755fe89..8228914 100644 --- a/src/example/nes.asm +++ b/src/example/nes.asm @@ -7,64 +7,63 @@ option nes-vector,nmi,nmi option nes-vector,brk,nmi +vsync: macro +.wait + lda $2002 + bpl wait + endm + start: org $c000 - ; - ; Code taken from NES example - ; + sei + cld + ldx #$ff + txs - sei ; disable IRQs - cld ; disable decimal mode - ldx #$40 - stx $4017 ; dsiable APU frame IRQ - ldx #$ff ; Set up stack - txs ; . - inx ; now X = 0 - stx $2000 ; disable NMI - stx $2001 ; disable rendering - stx $4010 ; disable DMC IRQs - - ;; first wait for vblank to make sure PPU is ready -vblankwait1: - bit $2002 - bpl vblankwait1 - -clear_memory: - lda #$00 - sta $0000, x - sta $0100, x - sta $0200, x - sta $0300, x - sta $0400, x - sta $0500, x - sta $0600, x - sta $0700, x - inx - bne clear_memory - - ;; second wait for vblank, PPU is ready after this -vblankwait2: - bit $2002 - bpl vblankwait2 - -clear_palette: - ;; Need clear both palettes to $00. Needed for Nestopia. Not - ;; needed for FCEU* as they're already $00 on powerup. - lda $2002 ; Read PPU status to reset PPU address - lda #$3f ; Set PPU address to BG palette RAM ($3F00) + ; this sets up the PPU. Apparently. + lda #%00001000 + sta $2000 + lda #%00011110 + sta $2001 + + ; Set PPU to palette + ; +loadpalette: + lda #$3f sta $2006 lda #$00 - sta $2006 + sta $2006 - ldx #$20 ; Loop $20 times (up to $3F20) - lda #$00 ; Set each entry to $00 -.loop + ; Load the palette + ; + ldx #0 +.loop lda palette,x sta $2007 - dex + inx + cpx #$20 bne loop - lda #%10000000 ; intensify blues - sta $2001 + ; Wait for a vysnc before loading the name table + ; + vsync + + ; Load the name map + ; +load_namemap: + lda #$20 + sta $2006 + lda #$20 + sta $2006 + + ldx #0 +.loop lda map,x + cmp #$ff + beq done + sta $2007 + inx + jmp loop +.done + forever: jmp forever @@ -72,11 +71,29 @@ forever: nmi: rti +palette: + db 15, 0, 16, 48, 15, 1, 33, 49, 15, 6, 22, 38, 15, 9, 25, 41 + db 15, 0, 16, 48, 15, 1, 33, 49, 15, 6, 22, 38, 15, 9, 25, 41 + +map: + db 'H'-'@' + db 'E'-'@' + db 'L'-'@' + db 'L'-'@' + db 'O'-'@' + db 0 + db 'W'-'@' + db 'O'-'@' + db 'R'-'@' + db 'L'-'@' + db 'D'-'@' + db 255 + ; -; Dummy VROM +; VROM ; org 0 bank 1 - db 0 + incbin "tiles.chr" diff --git a/src/example/tiles.chr b/src/example/tiles.chr Binary files differnew file mode 100755 index 0000000..9986eaf --- /dev/null +++ b/src/example/tiles.chr |