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Made oamInsertMultiSprite a real function, just needs a list of actors to stop using $0200 now

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This commit is contained in:
Andrew Kesterson
2012-11-04 13:25:11 -05:00
parent 7ea451361a
commit 637764ff28
2 changed files with 61 additions and 21 deletions
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14
defines.S
View File

@@ -1,2 +1,16 @@
.alias curSpriteDataRead curSpriteDataLo
.alias curSpriteDataWrite curSpriteDataHi
.macro storeStackReturn ; storeStackReturn
PLA
STA prevReturnAddrHi
PLA
STA prevReturnAddrLo
.macend
.macro restoreStackReturn
LDA prevReturnAddrLo
PHA
LDA prevReturnAddrhi
PHA
.macend

66
nesgame.S
View File

@@ -15,13 +15,20 @@
.include "defines.S"
.text zp ; zero page - this begins at $00
; all pointers should go here
;; $0000 - $000F is reserved for local variables/function args
.org $0010 ; $0010 - 002F reserved for pointers
.text zp
.org $0000
;; $0000 is reserved for things we use to extend PL/PH for call/return stacks
;; FIXME: Will need to expand this stuff once I start calling 2+
;; functions at once; e.g., JSR a -> JSR b -> JSR c...
;; will need to expand it to a real stack.
.space prevReturnAddrLo 1
.space prevReturnAddrHi 1
.org $0010
;; $0010 - 001F is reserved for global pointers
.space curSpriteDataLo 1
.space curSpriteDataHi 1
.org $0030
.org $0020
;; $0020 - 00FF is space for general purpose global variables
.space curSpriteLen 1
.space playery 1
.space playerx 1
@@ -193,22 +200,45 @@ _MAIN_LoadPaletteLoop:
LDA #$80
STA playerx
STA playery
;; Put mario in as the first multisprite
LDA #<sprMarioData
PHA
LDA #>sprMarioData
PHA
LDA sprMario
PHA
;; DO IT
JSR oamInsertMultiSprite
_MAIN_loop:
JMP _MAIN_loop ;; Loop forever
NMI:
;; 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
;; This is almost a reusable function ... store 'sprMario' as our
;; current sprite that we're about to draw
LDA sprMario
PLA
STA curSpriteLen
LDA #>sprMarioData
PLA
STA curSpriteDataHi
LDA #<sprMarioData
PLA
STA curSpriteDataLo
;; ----
_NMI_CopyMarioToOAM:
_looptop:
LDA playery ; set Y position
CLC
ADC (curSpriteDataLo), y
@@ -217,14 +247,7 @@ _NMI_CopyMarioToOAM:
LDA (curSpriteDataLo), y ; set tile number
STA $0200, y
INY
LDA pad1a
AND #%00000001
BNE _NMI_CopyMarioToOAM_padup
LDA (curSpriteDataLo), y
JMP _NMI_CopyMarioToOAM_paddone
_NMI_CopyMarioToOAM_padup:
LDA sprMarioData, y ; set attributes
_NMI_CopyMarioToOAM_paddone:
STA $0200, y
INY
LDA playerx ; set X position
@@ -234,8 +257,11 @@ _NMI_CopyMarioToOAM_paddone:
INY
INX ; increment the sprite counter
CPX curSpriteLen ; any more sprites in the current multisprite?
BNE _NMI_CopyMarioToOAM
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
;; to pull OAM from $0200, and do a DMA transfer.