AUTO_INC_NONE = $000000
AUTO_INC_1 = $100000
AUTO_INC_2 = $200000
AUTO_INC_4 = $300000
AUTO_INC_8 = $400000
AUTO_INC_16 = $500000
AUTO_INC_32 = $600000
AUTO_INC_64 = $700000
AUTO_INC_128 = $800000
AUTO_INC_256 = $900000
AUTO_INC_512 = $A00000
AUTO_INC_40 = $B00000
AUTO_INC_80 = $C00000
AUTO_INC_160 = $D00000
AUTO_INC_320 = $E00000
AUTO_INC_640 = $F00000

DISABLED = 0
ENABLED = 1

VERA_L_BPP1 = %00000000
VERA_L_BPP2 = %00000001
VERA_L_BPP4 = %00000010
VERA_L_BPP8 = %00000011

VERA_L_BITMAP = %00000100
VERA_L_T256C = %00001000

VERA_L_32W = %00000000
VERA_L_64W = %00010000
VERA_L_128W = %00100000
VERA_L_256W = %00110000

VERA_L_32H = %00000000
VERA_L_64H = %01000000
VERA_L_128H = %10000000
VERA_L_256H = %11000000

VERA_TILESIZE8x8 = %00000000
VERA_TILESIZE16x8 = %00000001
VERA_TILESIZE8x16 = %00000010
VERA_TILESIZE16x16 = %00000011

; The base address of the VERA chip
VERA_BASE = $00DF00

; Offsets (relative to VERA_BASE) for each VERA register

VERA_ADDRx_L = VERA_BASE + 00
VERA_ADDRx_M = VERA_BASE + 01
VERA_ADDRx_H = VERA_BASE + 02

; Accssible with ADDRSEL == 0
VERA_ADDR0_L = VERA_BASE + 00
VERA_ADDR0_M = VERA_BASE + 01
VERA_ADDR0_H = VERA_BASE + 02

; Accssible with ADDRSEL == 1
VERA_ADDR1_L = VERA_BASE + 00
VERA_ADDR1_M = VERA_BASE + 01
VERA_ADDR1_H = VERA_BASE + 02

VERA_DATA0 = VERA_BASE + $03
VERA_DATA1 = VERA_BASE + $04

VERA_CTRL = VERA_BASE + $05
VERA_IEN = VERA_BASE + $06
VERA_ISR = VERA_BASE + $06
VERA_IRQLINE_L = VERA_BASE + $07
VERA_SCANLINE_L = VERA_BASE + $08

; Accssible with DCSEL == 0
VERA_DC_VIDEO = VERA_BASE + $09
VERA_DC_HSCALE = VERA_BASE + $0A
VERA_DC_VSCALE = VERA_BASE + $0B
VERA_DC_BORDER = VERA_BASE + $0C

; Accssible with DCSEL == 1
VERA_DC_HSTART = VERA_BASE + $09
VERA_DC_HSTOP = VERA_BASE + $0A
VERA_DC_VSTART = VERA_BASE + $0B
VERA_DC_VSTOP = VERA_BASE + $0C

; Layer 0
VERA_L0_CONFIG = VERA_BASE + $0D
VERA_L0_MAPBASE = VERA_BASE + $0E
VERA_L0_TILEBASE = VERA_BASE + $0F
VERA_L0_HSCROLL_L = VERA_BASE + $10
VERA_L0_HSCROLL_H = VERA_BASE + $11
VERA_L0_VSCROLL_L = VERA_BASE + $12
VERA_L0_VSCROLL_H = VERA_BASE + $13

; Layer 1
VERA_L1_CONFIG = VERA_BASE + $14
VERA_L1_MAPBASE = VERA_BASE + $15
VERA_L1_TILEBASE = VERA_BASE + $16
VERA_L1_HSCROLL_L = VERA_BASE + $17
VERA_L1_HSCROLL_H = VERA_BASE + $18
VERA_L1_VSCROLL_L = VERA_BASE + $19
VERA_L1_VSCROLL_H = VERA_BASE + $1A

; Audio
VERA_AUDIO_CTRL = VERA_BASE + $1B
VERA_AUDIO_RATE = VERA_BASE + $1C
VERA_AUDIO_DATA = VERA_BASE + $1D

; SPI (Unused in prototype four!)
VERA_SPI_DATA = VERA_BASE + $1E
VERA_SPI_CTRL = VERA_BASE + $1F

; VRAM layout
VERA_PSG_BASE = $1F9C0
VERA_PALETTE_BASE = $1FA00
VERA_SPRITE_ATTR_BASE = $1FC00

; vpoke
;   writes an immediate byte to a given register
vpoke .macro reg, value
    php
    rep #$20
    .al
    pha

    sep #$20
    .as

    lda #\value
    sta \reg
    
    rep #$20
    .al
    pla
    plp
.endmacro

; vera_address_set  - sets the address registers to the passed in value
vera_address_set .macro addr
    php
    rep #$20
    .al
    pha

    sep #$20
    .as

    lda #\addr & $ff
    sta VERA_ADDRx_L
    
    lda #(\addr >> 8) & $ff
    sta VERA_ADDRx_M
    
    lda #(\addr >> 16) & $ff
    sta VERA_ADDRx_H
    
    rep #$20
    .al
    pla
    plp
.endmacro