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Milestone 3.5, tiles and sprites both present on the screen. Also started breaking the code out into libraries for easier editing and maintenance.

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This commit is contained in:
Andrew Kesterson
2012-11-06 23:30:20 -05:00
parent 38e8607572
commit d17de5971c
5 changed files with 296 additions and 104 deletions
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214
nesgame.S
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@@ -13,7 +13,7 @@
.byte $00,$00,$00,$00 ; Reserved bytes
.byte $00,$00,$00,$00 ; Reserved bytes
.include "defines.S"
.require "include/defines.S"
.text zp
.org $0000
@@ -25,12 +25,20 @@
.space prevReturnAddrHi 1
.org $0010
;; $0010 - 001F is reserved for global pointers
.space curPaletteLo 1
.space curPaletteHi 1
.space curSpriteOAMIndexLo 1
.space curSpriteOAMIndexHi 1
.space curBackgroundLo 1
.space curBackgroundHi 1
.space curBackgroundAttrLo 1
.space curBackgroundAttrHi 1
.space curSpriteDataLo 1
.space curSpriteDataHi 1
.org $0020
;; $0020 - 00FF is space for general purpose global variables
;; $0020 - 00FF is space for general purpose global variable
.space curBackgroundLen 1
.space curBackgroundAttrLen 1
.space curSpriteLen 1
.space playery 1
.space playerx 1
@@ -43,10 +51,20 @@
.space pad1left 1
.space pad1right 1
.space pad1areleased 1
.space multiSpriteList 16 ; reserve 6 words for the list of multisprites
; currently on screen, each one listed as a
; WORD address
.space tempdivident 1
.space tempdivisor 1
.space tempdivresult 1
.space tempdivmodulus 1
.text
.org $C000 ;; PRG bank code starts at 0xC000
.require "include/math.S"
.require "include/graphics.S"
;; START will be called by the NES whenever the system boots
;; or when the reset button is pressed (think of _start in libc )
;; but the fact that the NES looks at "START" is only because we
@@ -113,51 +131,18 @@ _START_vblankwait2:
BPL _START_vblankwait2 ;; once we've gotten 1 vblank,
;; cleared mem, and gotten another vblank,
;; the PPU is ready. Wait for it.
MAIN:
JMP main
main:
;; horray, here is main()
_MAIN_LoadPalettes:
LDA $2002 ; The PPU Memory address at $2006 expects
; the high byte of the palette address first,
; then the low byte, but we can't know
; which one it's expecting right now, so we
; read the PPU status at $2002 to reset the
; high/low latch on $2006.
LDA #$3F ; we're populating the second palette, at $3F10
STA $2006
LDA #$00
STA $2006
LDX #$00
_MAIN_LoadPaletteLoop:
LDA palette, x ; Loop over each index of the byte array at
STA $2007 ; 'palette', store each one into the accumulator
INX ; and then store the accumulator into the PPU
CPX #$20 ; .. compare X to 20 (size of 'palette'), and
BNE _MAIN_LoadPaletteLoop ; loop as long as the Zero flag isn't set (NE)
;; All sprites live between 0200-02FF; there are a max of 64 sprites
;; on screen, and each one has a 4 byte struct describing it.
;; *(sprite + 0) = y position
;; *(sprite + 1) = tile index (0-FF) in the pattern table for pixels
;; *(sprite + 2) = attributes. Color palette, priority, and mirroring.
;; 76543210
;; ||| ||
;; ||| ++- Color Palette of sprite. Choose which set of 4 from
;; ||| the 16 colors to use. You can select sprite colors only
;; ||| in groups of 4 on 4 byte boundaries; so you can select
;; ||| colors 0-3, 4-7, 8-11, and 12-15, but not 2-5, for
;; ||| example. Palette construction and use is an art in
;; ||| itself!
;; |||
;; ||+------ Priority (0: in front of background; 1: behind background)
;; |+------- Flip sprite horizontally
;; +-------- Flip sprite vertically
;; *(sprite + 3) = x position
;; All the sprite OAM data is initialized at the bottom of bank 1
;; at .org $FF00
PHA
LDA #<palette
PHA
LDA #>palette
PHA
JSR paletteLoad
;; $2000 is the PPU Control register, controlled by various bitflags.
;;
;; 7654 3210
@@ -175,9 +160,6 @@ _MAIN_LoadPaletteLoop:
;; +--------- Generate an NMI at the start of the
;; vertical blanking interval (0: off; 1: on)
LDA #%10000000 ; enable NMI (so we get a function call every
; vblank), and draw sprites from table 0
STA $2000
;; The PPU mask is set at $2001, the 2nd PPU Control register, and it
;; sets one config option for every bit of the byte
@@ -195,10 +177,7 @@ _MAIN_LoadPaletteLoop:
;; |+------- Intensify greens (and darken other colors)
;; +-------- Intensify blues (and darken other colors)
LDA #%00010000 ;; turn on sprites, no more background color
STA $2001 ;; Write to PPU Control Register 2
LDX #$0
LDA #$80
STA playerx
STA playery
@@ -232,59 +211,36 @@ _MAIN_LoadPaletteLoop:
STA curSpriteOAMIndexHi
JSR oamInsertMultiSprite
;; ---------------------------
_bgcall:
LDA bgattrsize
PHA
LDA #>backgroundattrs
PHA
LDA #<backgroundattrs
PHA
LDA bgsize
PHA
LDA #>background
PHA
LDA #<background
PHA
JSR backgroundLoad
;; Apparently you do NOT set sprite and tile data while these are turned on, bad things
;; will happen!
LDA #%10010000 ; enable NMI (so we get a function call every
; vblank), and draw sprites from table 0
STA $2000
LDA #%10011110 ;; turn on sprites, turn on background, don't clip on the left
STA $2001 ;; Write to PPU Control Register 2
LDA #$00 ; hey PPU, stop friggin scrolling!
STA $2005
STA $2005
LDX #$0
_MAIN_loop:
JMP _MAIN_loop ;; Loop forever
;; Function : oamInsertMultiSprite
;;
;; Given the address of a multisprite, and its length (number of
;; subsprites), load the multisprite into the OAM memory at
;; index 0.
;;
;; Arguments on the stack:
;; - Length of multisprite
;; - High byte of multisprite's address
;; - Low byte of multisprite's address
;;
;; FIXME: Need to keep a list of all multisprites so I can append
;; new ones to the list, and remove dead ones; right now this all
;; presumes $0200 is the root for the multisprite, which will stop
;; being true once I have more than one.
oamInsertMultiSprite:
.invoke storeStackReturn
LDX #$0
LDY #$0
PLA
STA curSpriteLen
PLA
STA curSpriteDataHi
PLA
STA curSpriteDataLo
;; ----
_looptop:
LDA playery ; set Y position
CLC
ADC (curSpriteDataLo), y
STA (curSpriteOAMIndexLo), y
INY
LDA (curSpriteDataLo), y ; set tile number
STA (curSpriteOAMIndexLo), y
INY
LDA (curSpriteDataLo), y
STA (curSpriteOAMIndexLo), y
INY
LDA playerx ; set X position
CLC
ADC (curSpriteDataLo), y
STA (curSpriteOAMIndexLo), y
INY
INX ; increment the sprite counter
CPX curSpriteLen ; any more sprites in the current multisprite?
BNE _looptop
.invoke restoreStackReturn
RTS
NMI:
;; We need to copy all our OAM data to put sprites on screen during
;; vblank. $2003 is the PPU OAM address, so we're going to tell it
@@ -298,11 +254,63 @@ NMI:
; which takes ~513 cycles. An unrolled
; loop to do the same thing would take
; 3-4 times as long.
LDA #%10010000 ; enable NMI (so we get a function call every
; vblank), and draw sprites from table 0
STA $2000
LDA #%00011110 ;; turn on sprites, turn on background, don't clip on the left
STA $2001 ;; Write to PPU Control Register 2
LDA #$00 ; hey PPU, stop friggin scrolling!
STA $2005
STA $2005
RTI ; just return
palette:
.byte $0F,$31,$32,$33,$0F,$35,$36,$37,$0F,$39,$3A,$3B,$0F,$3D,$3E,$0F
.byte $0F,$1C,$15,$14,$0F,$02,$38,$3C,$0F,$1C,$15,$14,$0F,$02,$38,$3C
.byte $22,$29,$1A,$0F,$22,$36,$17,$0F,$22,$30,$21,$0F,$22,$27,$17,$0F ;;background palette
.byte $22,$1C,$15,$14,$22,$02,$38,$3C,$22,$1C,$15,$14,$22,$02,$38,$3C ;;sprite palette
bgsize:
.byte $80
bgattrsize:
.byte $08
background:
.byte $24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24 ;;row 1
.byte $24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24 ;;all sky
.byte $24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24 ;;row 2
.byte $24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24 ;;all sky
.byte $24,$24,$24,$24,$45,$45,$24,$24,$45,$45,$45,$45,$45,$45,$24,$24 ;;row 3
.byte $24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$53,$54,$24,$24 ;;some brick tops
.byte $24,$24,$24,$24,$47,$47,$24,$24,$47,$47,$47,$47,$47,$47,$24,$24 ;;row 4
.byte $24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$24,$55,$56,$24,$24 ;;brick bottoms
backgroundattrs:
.byte %00000000,%00010000,%01010000,%00010000
.byte %00000000,%00000000,%00000000,%00110000
.byte $24,$24,$24,$24
.byte $47,$47,$24,$24
.byte $47,$47,$47,$47
.byte $47,$47,$24,$24
.byte $24,$24,$24,$24
.byte $24,$24,$24,$24
.byte $24,$24,$24,$24
.byte $55,$56,$24,$24 ;;brick bottoms
;; All sprites live between 0200-02FF; there are a max of 64 sprites
;; on screen, and each one has a 4 byte struct describing it.
;; *(sprite + 0) = y position
;; *(sprite + 1) = tile index (0-FF) in the pattern table for pixels
;; *(sprite + 2) = attributes. Color palette, priority, and mirroring.
;; 76543210
;; ||| ||
;; ||| ++- Color Palette of sprite. Choose which set of 4 from
;; ||| the 16 colors to use. You can select sprite colors only
;; ||| in groups of 4 on 4 byte boundaries; so you can select
;; ||| colors 0-3, 4-7, 8-11, and 12-15, but not 2-5, for
;; ||| example. Palette construction and use is an art in
;; ||| itself!
;; |||
;; ||+------ Priority (0: in front of background; 1: behind background)
;; |+------- Flip sprite horizontally
;; +-------- Flip sprite vertically
;; *(sprite + 3) = x position
sprMario:
.byte $08 ; Total number of subsprites in this metasprite
sprMarioData: