Add registers.asm file. Refer to registers by name.
This commit is contained in:
Colin McMillen
parent
6d94f5d032
commit
1925869fb6
49
pewpew.asm
49
pewpew.asm
@ -1,6 +1,6 @@
|
||||
.INCLUDE "header.asm"
|
||||
.INCLUDE "InitSNES.asm"
|
||||
|
||||
.INCLUDE "registers.asm"
|
||||
|
||||
.BANK 0 SLOT 0
|
||||
.ORG 0
|
||||
@ -11,31 +11,29 @@
|
||||
; 00-0F: scratch space for functions.
|
||||
; 10-13: controller state.
|
||||
; 14-17: 32-bit counter of vblanks.
|
||||
; 20-22: [rgb] color values to use for background color.
|
||||
; 20-22: RGB color values to use for background color, from [0-31].
|
||||
|
||||
|
||||
Start:
|
||||
InitSNES ; Initialize SNES.
|
||||
InitSNES ; Initialize SNES.
|
||||
|
||||
; Turn on the screen.
|
||||
; $2100: Screen display register [INIDISP]
|
||||
;
|
||||
; Format: x000bbbb
|
||||
; x: 0 = screen on, 1 = screen off, bbbb: Brightness ($0-$F)
|
||||
lda #%00001111
|
||||
sta $2100
|
||||
sta INIDISP
|
||||
|
||||
; Enable NMI interrupt & joypad.
|
||||
; Register $4200: Counter enable [NMITIMEN]
|
||||
; n-vh---j n: NMI interrupt enable v: vertical counter enable
|
||||
; h: horizontal counter enable j: joypad enable
|
||||
lda #$81
|
||||
sta $4200
|
||||
sta NMITIMEN
|
||||
|
||||
; Store zeroes to the controller status registers.
|
||||
; TODO(mcmillen): is this needed? I think the system should do this.
|
||||
stz $4218
|
||||
stz $4219
|
||||
; TODO(mcmillen): is this needed? I think the system will overwrite these
|
||||
; automatically.
|
||||
stz JOY1H
|
||||
stz JOY1L
|
||||
|
||||
; Write something recognizable into our scratch space.
|
||||
jsr FillScratch
|
||||
@ -82,12 +80,11 @@ JoypadHandler:
|
||||
; Format: AXLR0000
|
||||
; $4219: Joypad #1 status [JOY1H]
|
||||
; Format: BYsSudlr (s=select, S=start, udlr = joypad)
|
||||
; Joypad #2 status would be $421A [JOY2L] and $421B [JOY2H].
|
||||
jsr JoypadDebug ; DEBUG
|
||||
|
||||
; TODO(mcmillen): read joypad from local memory instead of registers?
|
||||
JoypadUp:
|
||||
lda $4219
|
||||
lda JOY1H
|
||||
and #$08 ; Up
|
||||
cmp #$08
|
||||
bne JoypadDown ; Button not pressed.
|
||||
@ -97,8 +94,8 @@ JoypadUp:
|
||||
inc $20
|
||||
|
||||
JoypadDown:
|
||||
lda $4219
|
||||
and #$04 ; Down
|
||||
lda JOY1H
|
||||
and #$04
|
||||
cmp #$04
|
||||
bne JoypadLeft ; Button not pressed.
|
||||
lda $20
|
||||
@ -107,7 +104,7 @@ JoypadDown:
|
||||
dec $20
|
||||
|
||||
JoypadLeft:
|
||||
lda $4219
|
||||
lda JOY1H
|
||||
and #$02 ; Left
|
||||
cmp #$02
|
||||
bne JoypadRight ; Button not pressed.
|
||||
@ -117,7 +114,7 @@ JoypadLeft:
|
||||
dec $22
|
||||
|
||||
JoypadRight:
|
||||
lda $4219
|
||||
lda JOY1H
|
||||
and #$01
|
||||
cmp #$01 ; Right
|
||||
bne JoypadB ; Button not pressed.
|
||||
@ -127,7 +124,7 @@ JoypadRight:
|
||||
inc $22
|
||||
|
||||
JoypadB:
|
||||
lda $4219
|
||||
lda JOY1H
|
||||
and #$80 ; B
|
||||
cmp #$80
|
||||
bne JoypadY ; Button not pressed.
|
||||
@ -137,7 +134,7 @@ JoypadB:
|
||||
inc $21
|
||||
|
||||
JoypadY:
|
||||
lda $4219
|
||||
lda JOY1H
|
||||
and #$40 ; Y
|
||||
cmp #$40
|
||||
bne JoypadDone ; Button not pressed.
|
||||
@ -153,13 +150,13 @@ JoypadDone:
|
||||
|
||||
JoypadDebug:
|
||||
; Load joypad registers into RAM for easier inspection.
|
||||
lda $4218
|
||||
lda JOY1L
|
||||
sta $10
|
||||
lda $4219
|
||||
lda JOY1H
|
||||
sta $11
|
||||
lda $421A
|
||||
lda JOY2L
|
||||
sta $12
|
||||
lda $421B
|
||||
lda JOY2H
|
||||
sta $13
|
||||
rts
|
||||
|
||||
@ -175,7 +172,7 @@ SetBackgroundColor:
|
||||
asl
|
||||
.endr
|
||||
ora $20 ; Red.
|
||||
sta $2122
|
||||
sta CGDATA
|
||||
|
||||
; Compute the high-order byte and store it in CGDATA.
|
||||
lda $22 ; Blue.
|
||||
@ -188,12 +185,12 @@ SetBackgroundColor:
|
||||
lsr
|
||||
.endr
|
||||
ora $00
|
||||
sta $2122
|
||||
sta CGDATA
|
||||
|
||||
; Set the background color.
|
||||
; $2121 is the color palette selection register [CGADD].
|
||||
; Entry 0 corresponds to the SNES background color.
|
||||
stz $2121
|
||||
stz CGADD
|
||||
rts
|
||||
|
||||
|
||||
|
||||
46
registers.asm
Normal file
46
registers.asm
Normal file
@ -0,0 +1,46 @@
|
||||
; Definitions of commonly-used special memory addresses.
|
||||
;
|
||||
; These are commonly called "registers" in online documentation, even though
|
||||
; that feels like a misnomer; these aren't necessarily hardware registers in
|
||||
; the same sense as PC, A, X, Y, and so on. Despite that, I call them
|
||||
; "registers" too, since that's what everyone else calls them.
|
||||
;
|
||||
; Where possible, I have named these register definitions in the same way that
|
||||
; they're named in Yoshi's venerable snes.txt document.
|
||||
|
||||
; $2100: Screen display register [INIDISP]
|
||||
; Format: x000bbbb
|
||||
; x: 0 = screen on, 1 = screen off, bbbb: Brightness ($0-$F)
|
||||
.define INIDISP $2100
|
||||
|
||||
; $2121: Color palette selection register [CGADD]
|
||||
; Entry 0 corresponds to the SNES background color.
|
||||
.define CGADD $2121
|
||||
|
||||
; $2122: Color data register [CGDATA]
|
||||
; The palette color format is 15-bit: [0bbbbbgg][gggrrrrr].
|
||||
; You will typically write to this register twice in a row: first for the
|
||||
; low-order byte (containing green and red) and then for the high-order byte
|
||||
; (containing blue and green).
|
||||
.define CGDATA $2122
|
||||
|
||||
; $4200: Counter enable [NMITIMEN]
|
||||
; n-vh---j n: NMI interrupt enable v: vertical counter enable
|
||||
; h: horizontal counter enable j: joypad enable
|
||||
.define NMITIMEN $4200
|
||||
|
||||
; $4218: Joypad #1 status [JOY1L]
|
||||
; Format: AXLR0000
|
||||
.define JOY1L $4218
|
||||
|
||||
; $4219: Joypad #1 status [JOY1H]
|
||||
; Format: BYsSudlr (s=select, S=start, udlr = joypad)
|
||||
.define JOY1H $4219
|
||||
|
||||
; $421A: Joypad #2 status [JOY2L]
|
||||
; Format: AXLR0000
|
||||
.define JOY2L $421A
|
||||
|
||||
; $421B: Joypad #2 status [JOY2H]
|
||||
; Format: BYsSudlr (s=select, S=start, udlr = joypad)
|
||||
.define JOY2H $421B
|
||||
Loading…
Reference in New Issue
Block a user