Various refactorings.
Rename InitializeFoo -> InitFoo. Break UpdateWorld into a few functions. shotArray -> playerShotArray.
This commit is contained in:
Colin McMillen
parent
98aedecd4c
commit
f51a544956
2
init.asm
2
init.asm
@ -2,7 +2,7 @@
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;- Standard SNES initialization routine, originally by Neviksti
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;------------------------------------------------------------------------
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.MACRO InitializeSNES
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.MACRO InitSNES
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sei ;disable interrupts
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clc ;switch to native mode
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xce
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119
pewpew.asm
119
pewpew.asm
@ -1,51 +1,7 @@
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.INCLUDE "header.asm"
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.INCLUDE "init.asm"
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.INCLUDE "registers.asm"
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; Memory layout:
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; 0000-000F: scratch space for functions.
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; 0010-0011: controller state of joypad #1.
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; 0012-0013: controller state of joypad #2.
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; 0014-0016: 24-bit counter of vblanks.
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; 0017-0019: RGB color values to use for background color, from [0-31].
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; 001A-001B: 16-bit pointer to next random byte.
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; [gap]
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; 0020-0021: (x, y) coordinates of player.
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; 0022: shot cooldown timer.
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; 0023: next-shot state.
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; [gap]
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; 0030-003F: (x, y) velocities of each of the 8 possible shot states.
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; 0040-009F: {sprite, x, y, x-velocity, y-velocity, unused} per shot.
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; If sprite is 0, the shot is disabled.
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; [gap]
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; Sprite table buffers -- copied each frame to OAM during VBlank, using DMA.
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; 1000-11FF: table 1 (4 bytes each: x/y coord, tile #, flip/priority/palette)
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; 1200-121F: table 2 (2 bits each: high x-coord bit, size)
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; 1220-12A0: scratch table. One byte per sprite for high x-coord & size.
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.define joy1 $10
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.define joy2 $12
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.define vBlankCounter $14
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.define backgroundRed $17
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.define backgroundGreen $18
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.define backgroundBlue $19
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.define randomBytePtr $1A
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.define playerX $20
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.define playerY $21
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.define shotCooldown $22
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.define nextShotState $23
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.define shotVelocityTable $30
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.define shotArray $40
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.define shotArrayLength 16
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.define shotSize 6
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.define numSprites 128
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.define spriteTableStart $1000
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.define spriteTable1Size $200
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.define spriteTable2Start $1200
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.define spriteTableSize $220
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.define spriteTableScratchStart $1220
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.INCLUDE "memory.asm"
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@ -94,7 +50,7 @@ rep #%00010000 ; 16-bit X/Y.
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Start:
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InitializeSNES
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InitSNES
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; By default we assume 16-bit X/Y and 8-bit A.
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; If any code wants to change this, it's expected to do so itself,
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@ -103,7 +59,7 @@ Start:
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SetA8Bit
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jsr LoadPaletteAndTileData
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jsr InitializeWorld
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jsr InitWorld
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; Set screen mode: 16x16 tiles for backgrounds, mode 1.
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lda #%11000001
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@ -253,7 +209,7 @@ LoadPaletteAndTileData:
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InitializeWorld:
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InitWorld:
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; Start the background color as a dark blue.
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lda #4
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sta backgroundBlue
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@ -452,7 +408,7 @@ MaybeShoot:
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cmp #0
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bne MaybeShootDone
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; Find the first empty spot in the shots array.
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ldx #shotArray
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ldx #playerShotArray
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-
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lda 0, X
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cmp #0
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@ -461,7 +417,7 @@ MaybeShoot:
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inx
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.endr
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; If we went all the way to the end, bail out.
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cpx #(shotArray + shotArrayLength * shotSize)
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cpx #(playerShotArray + playerShotArrayLength * shotSize)
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beq MaybeShootDone
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jmp -
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+
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@ -510,6 +466,14 @@ MaybeShootDone:
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UpdateWorld:
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jsr UpdateShotCooldown
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jsr UpdateShotPositions
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jsr UpdateBackgroundScroll
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rts
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UpdateShotCooldown:
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; Update shot cooldown.
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lda shotCooldown
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cmp #0
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@ -517,68 +481,72 @@ UpdateWorld:
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dec A
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sta shotCooldown
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+
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rts
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UpdateShotPositions:
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ldx #0
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; Update shot position.
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UpdateShot:
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lda shotArray, X
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UpdateShot: ; Updates position of one shot.
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lda playerShotArray, X
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cmp #0
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beq ShotDone
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; Add to the x-coordinate. If the carry bit is set, we went off the edge
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; of the screen, so disable the shot.
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lda shotArray + 3, X ; x-velocity.
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lda playerShotArray + 3, X ; x-velocity.
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sta $00
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bit #%10000000 ; Check whether the velocity is negative.
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bne UpdateShotWithNegativeXVelocity
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lda shotArray + 1, X
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lda playerShotArray + 1, X
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clc
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adc $00
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bcs DisableShot
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sta shotArray + 1, X ; Store new x-coord.
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sta playerShotArray + 1, X ; Store new x-coord.
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jmp UpdateShotY
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UpdateShotWithNegativeXVelocity:
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; TODO(mcmillen): wrap sprites when they go negative here, like we do
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; with y-velocities.
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lda shotArray + 1, X ; Current x.
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lda playerShotArray + 1, X ; Current x.
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clc
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adc $00
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bcc DisableShot
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sta shotArray + 1, X
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sta playerShotArray + 1, X
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jmp UpdateShotY
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UpdateShotY:
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; Add to the y-coordinate.
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lda shotArray + 4, X ; y-velocity.
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lda playerShotArray + 4, X ; y-velocity.
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sta $00
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bit #%10000000 ; Check whether the velocity is negative.
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bne UpdateShotWithNegativeYVelocity
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lda shotArray + 2, X
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lda playerShotArray + 2, X
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clc
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adc $00
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cmp #224
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bcs DisableShot
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sta shotArray + 2, X ; Store new y-coord.
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sta playerShotArray + 2, X ; Store new y-coord.
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jmp ShotDone
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UpdateShotWithNegativeYVelocity:
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lda shotArray + 2, X ; Current y.
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lda playerShotArray + 2, X ; Current y.
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cmp #224
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bcs + ; If the shot was "off the top" before moving, maybe we'll reap it.
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adc $00 ; Otherwise, just update it,
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sta shotArray + 2, X ; save the result,
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sta playerShotArray + 2, X ; save the result,
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jmp ShotDone ; and we know it shouldn't be reaped.
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+
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clc
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adc $00
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cmp #224
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bcc DisableShot ; If it's now wrapped around, reap it.
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sta shotArray + 2, X
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sta playerShotArray + 2, X
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jmp ShotDone
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DisableShot:
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stz shotArray, X
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stz playerShotArray, X
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ShotDone:
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; TODO(mcmillen): in places where we .rept inx (etc), is it faster to use
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@ -586,9 +554,14 @@ ShotDone:
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.rept shotSize
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inx
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.endr
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cpx #(shotArrayLength * shotSize)
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cpx #(playerShotArrayLength * shotSize)
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bne UpdateShot
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rts
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UpdateBackgroundScroll:
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; Make the background scroll. Horizontal over time; vertical depending on
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; player's y-coordinate.
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lda vBlankCounter
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@ -654,25 +627,25 @@ UpdateSprites:
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; Now add shots.
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sty $00 ; Save sprite table 2 index.
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ldy #0 ; Index into shotArray.
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ldy #0 ; Index into playerShotArray.
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-
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lda shotArray, Y
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lda playerShotArray, Y
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cmp #0
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beq + ; If not enabled, skip to next shot.
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; Update sprite table 1.
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sta spriteTableStart + 2, X ; sprite number
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lda shotArray + 1, Y
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lda playerShotArray + 1, Y
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sta spriteTableStart, X ; x
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lda shotArray + 2, Y
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lda playerShotArray + 2, Y
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sta spriteTableStart + 1, X ; y
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; Update secondary sprite table.
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phy ; Save shotArray index.
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phy ; Save playerShotArray index.
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ldy $00
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lda #%11000000
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sta spriteTableScratchStart, Y
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iny
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sty $00
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ply ; Restore shotArrayIndex.
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ply ; Restore playerShotArrayIndex.
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.rept 4
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inx
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@ -681,7 +654,7 @@ UpdateSprites:
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.rept shotSize
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iny
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.endr
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cpy #(shotArrayLength * shotSize)
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cpy #(playerShotArrayLength * shotSize)
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bne -
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; Now clear out the unused entries in the sprite table.
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