main.asm

;**************************************
; SUPER FX DEMO
;**************************************
.65816

.include define.inc
.include registers.inc
.include macros.inc
.include var.asm
.include assets.asm
.include superfx/main.asm

.65816

.org 808000
.base 0000

.include vectors.asm
.include clear.asm
.include dma.asm
.include joypad.asm
.include level.asm
.include object.asm

InitGSU_ROM:
    ; phb needed ?
    lda #02 ; set pbr to bank 02 (GSU ROM)
    sta PBR ; Program bank register

    lda #04 ; gsu/2
    sta VCR

    stz RAMBR
    stz ROMBR

    lda #08 ; screen base register = 70:0000 + N * 0x400
    ; can use double buffering by switching scbr on two successive frame ?
    ; double buffering in VRAM seems to be the norm when looking at starfox
    sta SCBR    ; = 70:2000

    ; nil nil HT1 RON RAN HT0 MD1 MD0
    ; 0   0   1   0   0   0   0   1  ; (MD 0b01) => 16 colors, (HT 0b10) => y=192
    lda #21 ; w/ RON
    sta @scmr_mirror

    lda #a0
    sta CFGR ; config, enable IRQ on STOP
    lda #01
    sta CLSR ; clock select register

    ; reset stack pointer
    ldx #1fff
    stx R10L

    rtl
InitGSU_ROM_end:

CallGSUFunction_ROM:
    ; give GSU access to ROM/RAM
    lda @scmr_mirror
    ora #18
    sta SCMR
    sta @scmr_mirror

    stx R15L

wait_for_gsu:
    lda SFRL
    bit #20
    bne @wait_for_gsu

    ; give back SNES access to ROM/RAM
    lda @scmr_mirror
    eor #18
    sta SCMR
    sta @scmr_mirror

    rtl
CallGSUFunction_ROM_end:


MainEntry:
    jsl !InitGSU

    ; ldx #@GSU_entry
    ; jsl !CallGSUFunction

    ldx #@GSU_clear_buffer
    jsl !CallGSUFunction

    ; draw_hline(96, 213, 184)
    ldx #0060 ; x0=96
    stx R01L
    ldx #00d5 ; x1=213
    stx R03L
    ldx #00b8 ; y=184
    stx R02L
    ldx #00b8 ; y=184
    stx R04L
    ldx #C_MAGENTA
    stx R00L

    ldx #@GSU_draw_line
    jsl !CallGSUFunction

; ---- ***
    ; LOOP_1A
    ; r0=color
    ldx #C_MAGENTA
    stx R00L
    ; r1=x0
    ldx #002c
    stx R01L
    ; r2=y0
    ldx #0080
    stx R02L
    ; r3=x1
    ldx #0068
    stx R03L
    ; r4=y1
    ldx #001c
    stx R04L
    ldx #@GSU_draw_line
    jsl !CallGSUFunction

    ; LOOP_1B
    ; r0=color
    ldx #C_YELLOW
    stx R00L
    ; r1=x0
    ldx #0068
    stx R01L
    ; r2=y0
    ldx #001c
    stx R02L
    ; r3=x1
    ldx #009c
    stx R03L
    ; r4=y1
    ldx #0057
    stx R04L
    ldx #@GSU_draw_line
    jsl !CallGSUFunction

    ; LOOP_2
    ; r0=color
    ldx #C_BLUE
    stx R00L
    ; r1=x0
    ldx #009c
    stx R01L
    ; r2=y0
    ldx #0057
    stx R02L
    ; r3=x1
    ldx #002c
    stx R03L
    ; r4=y1
    ldx #0080
    stx R04L
    ldx #@GSU_draw_line
    jsl !CallGSUFunction
; ---- ***

    ; ---- Release Forced Blank
    .call VRAM_DMA_TRANSFER 0000, screen_base, 5400; BG1_SCBR_SIZE
    ; .call VRAM_DMA_TRANSFER 0000, screen_base, 5400 ; 5400 is enough to copy first 672 tiles coposing the center screen
    lda #0f             ; release forced blanking, set screen to full brightness
    sta INIDISP

    lda #cf    ; trigger IRQ on line 207
    sta VTIMEL

    lda #a1             ; enable VIRQ, NMI, turn on automatic joypad polling
    sta NMITIMEN
    cli
MainLoop:
    jsr @WaitNextVBlank

    jsr @HandleInput

    jmp @MainLoop

.include info.asm