diff options
Diffstat (limited to 'src/jetpac.s')
| -rw-r--r-- | src/jetpac.s | 67 |
1 files changed, 66 insertions, 1 deletions
diff --git a/src/jetpac.s b/src/jetpac.s index 16fa292..79fec84 100644 --- a/src/jetpac.s +++ b/src/jetpac.s @@ -36,6 +36,7 @@ .include "../include/asm.s" .include "../include/joypad.s" .include "../include/globals.s" +.include "../include/debug.s" .include "assets.s" .include "background.s" @@ -45,7 +46,68 @@ .include "enemies.s" .include "title.s" .include "driver.s" -.include "vectors.s" +.include "interrupts.s" + +;; Pretty standard reset function, nothing crazy. +.proc reset + ;; Disable interrupts and decimal mode. + sei + cld + + ;; Disable APU frame counter. + ldx #$40 + stx APU::m_frame_counter + + ;; Setup the stack. + ldx #$FF + txs + + ;; Disable NMIs and the APU's DMC. + inx + stx PPU::m_control + stx PPU::m_mask + stx APU::m_dmc + + ;; First PPU wait. + bit PPU::m_status +@vblankwait1: + bit PPU::m_status + bpl @vblankwait1 + + ;; Initialize the counter for frame drops before any NMIs can come in. + .ifdef PARTIAL + lda #0 + sta Debug::zp_frame_drops + .endif + + ;; Reset all sprites by simply moving the Y coordinate out of screen. + lda #$EF + ldx #0 +@sprite_reset_loop: + sta OAM::m_sprites, x + inx + inx + inx + inx + bne @sprite_reset_loop + + ;; DMA setup for sprite reset. + lda #$00 + sta OAM::m_address + lda #$02 + sta OAM::m_dma + + ;; Second PPU wait. After that the PPU is stable. +@vblankwait2: + bit PPU::m_status + bpl @vblankwait2 + + ;; NOTE: palettes are not initialized here as it's going to be one of the + ;; first things done on `main` code. + + __fallthrough__ main +.endproc + .proc main ;; Disable the PPU and zero out variables which shadow PPU registers. @@ -148,3 +210,6 @@ ;; TODO: allow to start over, reset flags, control register, etc. jmp @over .endproc + +.segment "VECTORS" + .addr nmi, reset, irq |