ref: 8bf76af5a7360d9e86a24e3d9750329f354b3ac3
parent: e2838892d69c12fdafe3a40bd7386e7b26506282
author: Rangi <[email protected]>
date: Tue Mar 23 16:47:32 EDT 2021
Consistent comments in the tileset animation engine
--- a/engine/tilesets/tileset_anims.asm
+++ b/engine/tilesets/tileset_anims.asm
@@ -1,8 +1,10 @@
_AnimateTileset::
-; Iterate over a given pointer array of
-; animation functions (one per frame).
+; Increment [hTileAnimFrame] and run that frame's function
+; from the array pointed to by wTilesetAnim.
-; Typically in WRAM bank 1, VRAM bank 0.
+; Called in WRAM bank 1, VRAM bank 0, so map tiles
+; $80 and above in VRAM bank 1 cannot be animated
+; without switching to that bank themselves.
ld a, [wTilesetAnim]
ld e, a
@@ -20,7 +22,7 @@
add hl, de
; 2-byte parameter
-; All functions take input de.
+; All functions take input de
ld e, [hl]
inc hl
ld d, [hl]
@@ -51,7 +53,7 @@
TilesetParkAnim:
dw vTiles2 tile $14, AnimateWaterTile
dw NULL, WaitTileAnimation
- dw vTiles2 tile $5f, AnimateFountain
+ dw vTiles2 tile $5f, AnimateFountainTile
dw NULL, WaitTileAnimation
dw NULL, AnimateWaterPalette
dw NULL, WaitTileAnimation
@@ -92,9 +94,9 @@
UnusedTilesetAnim1: ; unreferenced
; Scrolls tile $03 like water, but also has the standard $03 flower tile.
- dw vTiles2 tile $03, WriteTileToBuffer
+ dw vTiles2 tile $03, ReadTileToAnimBuffer
dw wTileAnimBuffer, ScrollTileRightLeft
- dw vTiles2 tile $03, WriteTileFromBuffer
+ dw vTiles2 tile $03, WriteTileFromAnimBuffer
dw NULL, WaitTileAnimation
dw NULL, WaitTileAnimation
dw NULL, WaitTileAnimation
@@ -106,9 +108,9 @@
UnusedTilesetAnim2: ; unreferenced
; Scrolls tile $14 like cave water.
- dw vTiles2 tile $14, WriteTileToBuffer
+ dw vTiles2 tile $14, ReadTileToAnimBuffer
dw wTileAnimBuffer, ScrollTileRightLeft
- dw vTiles2 tile $14, WriteTileFromBuffer
+ dw vTiles2 tile $14, WriteTileFromAnimBuffer
dw NULL, WaitTileAnimation
dw NULL, WaitTileAnimation
dw NULL, WaitTileAnimation
@@ -133,11 +135,11 @@
dw NULL, DoneTileAnimation
TilesetEliteFourRoomAnim:
- dw NULL, LavaBubbleAnim2
+ dw NULL, AnimateLavaBubbleTile2
dw NULL, WaitTileAnimation
dw NULL, WaitTileAnimation
dw NULL, WaitTileAnimation
- dw NULL, LavaBubbleAnim1
+ dw NULL, AnimateLavaBubbleTile1
dw NULL, WaitTileAnimation
dw NULL, StandingTileFrame8
dw NULL, DoneTileAnimation
@@ -144,47 +146,47 @@
UnusedTilesetAnim3: ; unreferenced
; Scrolls tile $53 like a waterfall; scrolls tile $03 like cave water.
- dw vTiles2 tile $53, WriteTileToBuffer
+ dw vTiles2 tile $53, ReadTileToAnimBuffer
dw wTileAnimBuffer, ScrollTileDown
dw wTileAnimBuffer, ScrollTileDown
- dw vTiles2 tile $53, WriteTileFromBuffer
- dw vTiles2 tile $03, WriteTileToBuffer
+ dw vTiles2 tile $53, WriteTileFromAnimBuffer
+ dw vTiles2 tile $03, ReadTileToAnimBuffer
dw wTileAnimBuffer, ScrollTileRightLeft
- dw vTiles2 tile $03, WriteTileFromBuffer
- dw vTiles2 tile $53, WriteTileToBuffer
+ dw vTiles2 tile $03, WriteTileFromAnimBuffer
+ dw vTiles2 tile $53, ReadTileToAnimBuffer
dw wTileAnimBuffer, ScrollTileDown
dw wTileAnimBuffer, ScrollTileDown
- dw vTiles2 tile $53, WriteTileFromBuffer
+ dw vTiles2 tile $53, WriteTileFromAnimBuffer
dw NULL, DoneTileAnimation
UnusedTilesetAnim4: ; unreferenced
; Scrolls tile $54 like a waterfall; scrolls tile $03 like cave water.
- dw vTiles2 tile $54, WriteTileToBuffer
+ dw vTiles2 tile $54, ReadTileToAnimBuffer
dw wTileAnimBuffer, ScrollTileDown
dw wTileAnimBuffer, ScrollTileDown
- dw vTiles2 tile $54, WriteTileFromBuffer
+ dw vTiles2 tile $54, WriteTileFromAnimBuffer
dw NULL, WaitTileAnimation
- dw vTiles2 tile $03, WriteTileToBuffer
+ dw vTiles2 tile $03, ReadTileToAnimBuffer
dw wTileAnimBuffer, ScrollTileRightLeft
- dw vTiles2 tile $03, WriteTileFromBuffer
+ dw vTiles2 tile $03, WriteTileFromAnimBuffer
dw NULL, WaitTileAnimation
- dw vTiles2 tile $54, WriteTileToBuffer
+ dw vTiles2 tile $54, ReadTileToAnimBuffer
dw wTileAnimBuffer, ScrollTileDown
dw wTileAnimBuffer, ScrollTileDown
- dw vTiles2 tile $54, WriteTileFromBuffer
+ dw vTiles2 tile $54, WriteTileFromAnimBuffer
dw NULL, DoneTileAnimation
TilesetCaveAnim:
TilesetDarkCaveAnim:
- dw vTiles2 tile $14, WriteTileToBuffer
+ dw vTiles2 tile $14, ReadTileToAnimBuffer
dw NULL, FlickeringCaveEntrancePalette
dw wTileAnimBuffer, ScrollTileRightLeft
dw NULL, FlickeringCaveEntrancePalette
- dw vTiles2 tile $14, WriteTileFromBuffer
+ dw vTiles2 tile $14, WriteTileFromAnimBuffer
dw NULL, FlickeringCaveEntrancePalette
dw NULL, AnimateWaterPalette
dw NULL, FlickeringCaveEntrancePalette
- dw vTiles2 tile $40, WriteTileToBuffer
+ dw vTiles2 tile $40, ReadTileToAnimBuffer
dw NULL, FlickeringCaveEntrancePalette
dw wTileAnimBuffer, ScrollTileDown
dw NULL, FlickeringCaveEntrancePalette
@@ -192,20 +194,20 @@
dw NULL, FlickeringCaveEntrancePalette
dw wTileAnimBuffer, ScrollTileDown
dw NULL, FlickeringCaveEntrancePalette
- dw vTiles2 tile $40, WriteTileFromBuffer
+ dw vTiles2 tile $40, WriteTileFromAnimBuffer
dw NULL, FlickeringCaveEntrancePalette
dw NULL, DoneTileAnimation
TilesetIcePathAnim:
- dw vTiles2 tile $35, WriteTileToBuffer
+ dw vTiles2 tile $35, ReadTileToAnimBuffer
dw NULL, FlickeringCaveEntrancePalette
dw wTileAnimBuffer, ScrollTileRightLeft
dw NULL, FlickeringCaveEntrancePalette
- dw vTiles2 tile $35, WriteTileFromBuffer
+ dw vTiles2 tile $35, WriteTileFromAnimBuffer
dw NULL, FlickeringCaveEntrancePalette
dw NULL, AnimateWaterPalette
dw NULL, FlickeringCaveEntrancePalette
- dw vTiles2 tile $31, WriteTileToBuffer
+ dw vTiles2 tile $31, ReadTileToAnimBuffer
dw NULL, FlickeringCaveEntrancePalette
dw wTileAnimBuffer, ScrollTileDown
dw NULL, FlickeringCaveEntrancePalette
@@ -213,7 +215,7 @@
dw NULL, FlickeringCaveEntrancePalette
dw wTileAnimBuffer, ScrollTileDown
dw NULL, FlickeringCaveEntrancePalette
- dw vTiles2 tile $31, WriteTileFromBuffer
+ dw vTiles2 tile $31, WriteTileFromAnimBuffer
dw NULL, FlickeringCaveEntrancePalette
dw NULL, DoneTileAnimation
@@ -237,9 +239,9 @@
UnusedTilesetAnim5: ; unreferenced
; Scrolls tile $4f like cave water.
- dw vTiles2 tile $4f, WriteTileToBuffer
+ dw vTiles2 tile $4f, ReadTileToAnimBuffer
dw wTileAnimBuffer, ScrollTileRightLeft
- dw vTiles2 tile $4f, WriteTileFromBuffer
+ dw vTiles2 tile $4f, WriteTileFromAnimBuffer
dw NULL, WaitTileAnimation
dw NULL, WaitTileAnimation
dw NULL, WaitTileAnimation
@@ -289,6 +291,7 @@
ret
StandingTileFrame8:
+; Tick the wTileAnimationTimer, wrapping from 7 to 0.
ld a, [wTileAnimationTimer]
inc a
and %111
@@ -318,7 +321,7 @@
ScrollTileLeft:
ld h, d
ld l, e
- ld c, 4
+ ld c, LEN_2BPP_TILE / 4
.loop
rept 4
ld a, [hl]
@@ -332,7 +335,7 @@
ScrollTileRight:
ld h, d
ld l, e
- ld c, 4
+ ld c, LEN_2BPP_TILE / 4
.loop
rept 4
ld a, [hl]
@@ -349,9 +352,9 @@
ld d, [hl]
inc hl
ld e, [hl]
- ld bc, TILE_WIDTH * 2 - 2
+ ld bc, LEN_2BPP_TILE - 2
add hl, bc
- ld a, TILE_WIDTH / 2
+ ld a, LEN_2BPP_TILE / 4
.loop
ld c, [hl]
ld [hl], e
@@ -372,7 +375,7 @@
ScrollTileDown:
ld h, d
ld l, e
- ld de, TILE_WIDTH * 2 - 2
+ ld de, LEN_2BPP_TILE - 2
push hl
add hl, de
ld d, [hl]
@@ -379,7 +382,7 @@
inc hl
ld e, [hl]
pop hl
- ld a, TILE_WIDTH / 2
+ ld a, LEN_2BPP_TILE / 4
.loop
ld b, [hl]
ld [hl], d
@@ -397,13 +400,19 @@
jr nz, .loop
ret
-AnimateFountain:
+AnimateFountainTile:
+; Save the stack pointer in bc for WriteTile to restore
ld hl, sp+0
ld b, h
ld c, l
- ld hl, .frames
+
+ ld hl, .FountainTileFramePointers
+
+; A cycle of 8 frames, updating every tick
ld a, [wTileAnimationTimer]
and %111
+
+; hl = [.FountainTileFramePointers + a * 2]
add a
add l
ld l, a
@@ -413,68 +422,66 @@
ld a, [hli]
ld h, [hl]
ld l, a
+
+; Write the tile graphic from hl (now sp) to de (now hl)
ld sp, hl
ld l, e
ld h, d
jp WriteTile
-.frames
- dw .frame1
- dw .frame2
- dw .frame3
- dw .frame4
- dw .frame3
- dw .frame4
- dw .frame5
- dw .frame1
+.FountainTileFramePointers:
+ dw .FountainTile1
+ dw .FountainTile2
+ dw .FountainTile3
+ dw .FountainTile4
+ dw .FountainTile3
+ dw .FountainTile4
+ dw .FountainTile5
+ dw .FountainTile1
-.frame1 INCBIN "gfx/tilesets/fountain/1.2bpp"
-.frame2 INCBIN "gfx/tilesets/fountain/2.2bpp"
-.frame3 INCBIN "gfx/tilesets/fountain/3.2bpp"
-.frame4 INCBIN "gfx/tilesets/fountain/4.2bpp"
-.frame5 INCBIN "gfx/tilesets/fountain/5.2bpp"
+.FountainTile1: INCBIN "gfx/tilesets/fountain/1.2bpp"
+.FountainTile2: INCBIN "gfx/tilesets/fountain/2.2bpp"
+.FountainTile3: INCBIN "gfx/tilesets/fountain/3.2bpp"
+.FountainTile4: INCBIN "gfx/tilesets/fountain/4.2bpp"
+.FountainTile5: INCBIN "gfx/tilesets/fountain/5.2bpp"
AnimateWaterTile:
-; Draw a water tile for the current frame in VRAM tile at de.
-
-; Save sp in bc (see WriteTile).
+; Save the stack pointer in bc for WriteTile to restore
ld hl, sp+0
ld b, h
ld c, l
+; A cycle of 4 frames, updating every other tick
ld a, [wTileAnimationTimer]
-
-; 4 tile graphics, updated every other frame.
and %110
-; 2 x 8 = 16 bytes per tile
+; hl = .WaterTileFrames + a * 8
+; (a was pre-multiplied by 2 from 'and %110')
add a
add a
add a
-
- add LOW(WaterTileFrames)
+ add LOW(.WaterTileFrames)
ld l, a
ld a, 0
- adc HIGH(WaterTileFrames)
+ adc HIGH(.WaterTileFrames)
ld h, a
-; The stack now points to the start of the tile for this frame.
+; Write the tile graphic from hl (now sp) to de (now hl)
ld sp, hl
-
ld l, e
ld h, d
-
jp WriteTile
-WaterTileFrames:
+.WaterTileFrames:
INCBIN "gfx/tilesets/water/water.2bpp"
ForestTreeLeftAnimation:
+; Save the stack pointer in bc for WriteTile to restore
ld hl, sp+0
ld b, h
ld c, l
-; Only during the Celebi event.
+; Only animate this during the Celebi event
ld a, [wCelebiEvent]
bit CELEBIEVENT_FOREST_IS_RESTLESS_F, a
jr nz, .do_animation
@@ -482,8 +489,12 @@
jr .got_frames
.do_animation
+; A cycle of 2 frames, updating every tick
ld a, [wTileAnimationTimer]
call GetForestTreeFrame
+
+; hl = ForestTreeLeftFrames + a * 8
+; (a was pre-multiplied by 2 from GetForestTreeFrame)
add a
add a
add a
@@ -494,6 +505,7 @@
ld h, a
.got_frames
+; Write the tile graphic from hl (now sp) to tile $0c (now hl)
ld sp, hl
ld hl, vTiles2 tile $0c
jp WriteTile
@@ -507,11 +519,12 @@
INCBIN "gfx/tilesets/forest-tree/4.2bpp"
ForestTreeRightAnimation:
+; Save the stack pointer in bc for WriteTile to restore
ld hl, sp+0
ld b, h
ld c, l
-; Only during the Celebi event.
+; Only animate this during the Celebi event
ld a, [wCelebiEvent]
bit CELEBIEVENT_FOREST_IS_RESTLESS_F, a
jr nz, .do_animation
@@ -519,8 +532,12 @@
jr .got_frames
.do_animation
+; A cycle of 2 frames, updating every tick
ld a, [wTileAnimationTimer]
call GetForestTreeFrame
+
+; hl = ForestTreeRightFrames + a * 8
+; (a was pre-multiplied by 2 from GetForestTreeFrame)
add a
add a
add a
@@ -535,16 +552,18 @@
pop bc
.got_frames
+; Write the tile graphic from hl (now sp) to tile $0f (now hl)
ld sp, hl
ld hl, vTiles2 tile $0f
jp WriteTile
ForestTreeLeftAnimation2:
+; Save the stack pointer in bc for WriteTile to restore
ld hl, sp+0
ld b, h
ld c, l
-; Only during the Celebi event.
+; Only animate this during the Celebi event
ld a, [wCelebiEvent]
bit CELEBIEVENT_FOREST_IS_RESTLESS_F, a
jr nz, .do_animation
@@ -552,9 +571,15 @@
jr .got_frames
.do_animation
+; A cycle of 2 frames, updating every tick
ld a, [wTileAnimationTimer]
call GetForestTreeFrame
+
+; Offset by 1 frame from ForestTreeLeftAnimation
xor %10
+
+; hl = ForestTreeLeftFrames + a * 8
+; (a was pre-multiplied by 2 from GetForestTreeFrame)
add a
add a
add a
@@ -565,16 +590,18 @@
ld h, a
.got_frames
+; Write the tile graphic from hl (now sp) to tile $0c (now hl)
ld sp, hl
ld hl, vTiles2 tile $0c
jp WriteTile
ForestTreeRightAnimation2:
+; Save the stack pointer in bc for WriteTile to restore
ld hl, sp+0
ld b, h
ld c, l
-; Only during the Celebi event.
+; Only animate this during the Celebi event
ld a, [wCelebiEvent]
bit CELEBIEVENT_FOREST_IS_RESTLESS_F, a
jr nz, .do_animation
@@ -582,9 +609,15 @@
jr .got_frames
.do_animation
+; A cycle of 2 frames, updating every tick
ld a, [wTileAnimationTimer]
call GetForestTreeFrame
+
+; Offset by 1 frame from ForestTreeRightAnimation
xor %10
+
+; hl = ForestTreeRightFrames + a * 8
+; (a was pre-multiplied by 2 from GetForestTreeFrame)
add a
add a
add a
@@ -599,6 +632,7 @@
pop bc
.got_frames
+; Write the tile graphic from hl (now sp) to tile $0f (now hl)
ld sp, hl
ld hl, vTiles2 tile $0f
jp WriteTile
@@ -628,77 +662,93 @@
ret
AnimateFlowerTile:
-; No parameters.
-
-; Save sp in bc (see WriteTile).
+; Save the stack pointer in bc for WriteTile to restore
ld hl, sp+0
ld b, h
ld c, l
-; Alternate tile graphic every other frame
+; A cycle of 2 frames, updating every other tick
ld a, [wTileAnimationTimer]
and %10
-; CGB has different color mappings for flowers.
+; CGB has different tile graphics for flowers
ld e, a
ldh a, [hCGB]
and 1
add e
+; hl = .FlowerTileFrames + a * 16
swap a
ld e, a
ld d, 0
- ld hl, FlowerTileFrames
+ ld hl, .FlowerTileFrames
add hl, de
- ld sp, hl
+; Write the tile graphic from hl (now sp) to tile $03 (now hl)
+ ld sp, hl
ld hl, vTiles2 tile $03
-
jp WriteTile
-FlowerTileFrames:
+.FlowerTileFrames:
INCBIN "gfx/tilesets/flower/dmg_1.2bpp"
INCBIN "gfx/tilesets/flower/cgb_1.2bpp"
INCBIN "gfx/tilesets/flower/dmg_2.2bpp"
INCBIN "gfx/tilesets/flower/cgb_2.2bpp"
-LavaBubbleAnim1:
+AnimateLavaBubbleTile1:
+; Save the stack pointer in bc for WriteTile to restore
ld hl, sp+0
ld b, h
ld c, l
+
+; A cycle of 4 frames, updating every other tick
ld a, [wTileAnimationTimer]
and %110
+
+; Offset by 2 frames from AnimateLavaBubbleTile2
srl a
inc a
inc a
and %011
+
+; hl = LavaBubbleTileFrames + a * 16
swap a
ld e, a
ld d, 0
- ld hl, LavaBubbleFrames
+ ld hl, LavaBubbleTileFrames
add hl, de
+
+; Write the tile graphic from hl (now sp) to tile $5b (now hl)
ld sp, hl
ld hl, vTiles2 tile $5b
jp WriteTile
-LavaBubbleAnim2:
+AnimateLavaBubbleTile2:
+; Save the stack pointer in bc for WriteTile to restore
ld hl, sp+0
ld b, h
ld c, l
+
+; A cycle of 4 frames, updating every other tick
ld a, [wTileAnimationTimer]
and %110
+
+; hl = LavaBubbleTileFrames + a * 8
+; (a was pre-multiplied by 2 from 'and %110')
add a
add a
add a
ld e, a
ld d, 0
- ld hl, LavaBubbleFrames
+ ld hl, LavaBubbleTileFrames
add hl, de
+
+; Write the tile graphic from hl (now sp) to tile $38 (now hl)
ld sp, hl
ld hl, vTiles2 tile $38
jp WriteTile
-LavaBubbleFrames:
+LavaBubbleTileFrames:
INCBIN "gfx/tilesets/lava/1.2bpp"
INCBIN "gfx/tilesets/lava/2.2bpp"
INCBIN "gfx/tilesets/lava/3.2bpp"
@@ -705,19 +755,19 @@
INCBIN "gfx/tilesets/lava/4.2bpp"
AnimateTowerPillarTile:
-; Read from struct at de:
-; Destination (VRAM)
-; Address of the first tile in the frame array
+; Input de points to the destination in VRAM, then the source tile frames
+; Save the stack pointer in bc for WriteTile to restore
ld hl, sp+0
ld b, h
ld c, l
+; A cycle of 8 frames, updating every tick
ld a, [wTileAnimationTimer]
and %111
-; Get frame index a
- ld hl, .frames
+; a = [.TowerPillarTileFrameOffsets + a]
+ ld hl, .TowerPillarTileFrameOffsets
add l
ld l, a
ld a, 0
@@ -725,7 +775,7 @@
ld h, a
ld a, [hl]
-; Destination
+; de = the destination in VRAM
ld l, e
ld h, d
ld e, [hl]
@@ -733,7 +783,7 @@
ld d, [hl]
inc hl
-; Add the frame index to the starting address
+; hl = the source tile frames + offset a
add [hl]
inc hl
ld h, [hl]
@@ -742,34 +792,37 @@
adc h
ld h, a
+; Write the tile graphic from hl (now sp) to de (now hl)
ld sp, hl
ld l, e
ld h, d
jr WriteTile
-.frames
- db $00, $10, $20, $30, $40, $30, $20, $10
+.TowerPillarTileFrameOffsets:
+ db 0 tiles
+ db 1 tiles
+ db 2 tiles
+ db 3 tiles
+ db 4 tiles
+ db 3 tiles
+ db 2 tiles
+ db 1 tiles
StandingTileFrame:
+; Tick the wTileAnimationTimer.
ld hl, wTileAnimationTimer
inc [hl]
ret
AnimateWhirlpoolTile:
-; Update whirlpool tile using struct at de.
+; Input de points to the destination in VRAM, then the source tile frames
-; Struct:
-; VRAM address
-; Address of the first tile
-
-; Only does one of 4 tiles at a time.
-
-; Save sp in bc (see WriteTile).
+; Save the stack pointer in bc for WriteTile to restore
ld hl, sp+0
ld b, h
ld c, l
-; de = VRAM address
+; de = the destination in VRAM
ld l, e
ld h, d
ld e, [hl]
@@ -776,13 +829,13 @@
inc hl
ld d, [hl]
inc hl
-; Tile address is now at hl.
-; Get the tile for this frame.
+; A cycle of 4 frames, updating every tick
ld a, [wTileAnimationTimer]
- and %11 ; 4 frames x2
- swap a ; * 16 bytes per tile
+ and %11
+; hl = the source tile frames + a * 16
+ swap a
add [hl]
inc hl
ld h, [hl]
@@ -791,57 +844,51 @@
adc h
ld h, a
-; The stack now points to the desired frame.
+; Write the tile graphic from hl (now sp) to de (now hl)
ld sp, hl
-
ld l, e
ld h, d
-
jr WriteTile
-WriteTileFromBuffer:
-; Write tiledata at wTileAnimBuffer to de.
-; wTileAnimBuffer is loaded to sp for WriteTile.
-
+WriteTileFromAnimBuffer:
+; Save the stack pointer in bc for WriteTile to restore
ld hl, sp+0
ld b, h
ld c, l
+; Write the tile graphic from wTileAnimBuffer (now sp) to de (now hl)
ld hl, wTileAnimBuffer
ld sp, hl
-
ld h, d
ld l, e
jr WriteTile
-WriteTileToBuffer:
-; Write tiledata de to wTileAnimBuffer.
-; de is loaded to sp for WriteTile.
-
+ReadTileToAnimBuffer:
+; Save the stack pointer in bc for WriteTile to restore
ld hl, sp+0
ld b, h
ld c, l
+; Write the tile graphic from de (now sp) to wTileAnimBuffer (now hl)
ld h, d
ld l, e
ld sp, hl
-
ld hl, wTileAnimBuffer
-
; fallthrough
WriteTile:
-; Write one 8x8 tile ($10 bytes) from sp to hl.
+; Write one tile from sp to hl.
+; The stack pointer has been saved in bc.
-; Warning: sp is saved in bc so we can abuse pop.
-; sp is restored to address bc. Save sp in bc before calling.
+; This function cannot be called, only jumped to,
+; because it relocates the stack pointer to quickly
+; copy data with a "pop slide".
pop de
ld [hl], e
inc hl
ld [hl], d
-
-rept 7
+rept (LEN_2BPP_TILE - 2) / 2
pop de
inc hl
ld [hl], e
@@ -849,7 +896,7 @@
ld [hl], d
endr
-; restore sp
+; Restore the stack pointer from bc
ld h, b
ld l, c
ld sp, hl
@@ -858,24 +905,23 @@
AnimateWaterPalette:
; Transition between color values 0-2 for color 0 in palette 3.
-; No palette changes on DMG.
+; Don't update the palette on DMG
ldh a, [hCGB]
and a
ret z
-; We don't want to mess with non-standard palettes.
- ldh a, [rBGP] ; BGP
+; Don't update a non-standard palette order
+ ldh a, [rBGP]
cp %11100100
ret nz
-; Only update on even frames.
+; Only update on even ticks
ld a, [wTileAnimationTimer]
ld l, a
and 1 ; odd
ret nz
-; Ready for BGPD input...
-
+; Ready for BGPD input
ld a, (1 << rBGPI_AUTO_INCREMENT) palette PAL_BG_WATER
ldh [rBGPI], a
@@ -884,11 +930,11 @@
ld a, BANK(wBGPals1)
ldh [rSVBK], a
-; Update color 0 in order 0 1 2 1
+; A cycle of 4 colors (0 1 2 1), updating every other tick
ld a, l
- and %110 ; frames 0 2 4 6
+ and %110
jr z, .color0
- cp %100 ; frame 4
+ cp %100
jr z, .color2
; color1
@@ -920,14 +966,16 @@
ret
FlickeringCaveEntrancePalette:
-; No palette changes on DMG.
+; Don't update the palette on DMG
ldh a, [hCGB]
and a
ret z
-; We don't want to mess with non-standard palettes.
+
+; Don't update a non-standard palette order
ldh a, [rBGP]
cp %11100100
ret nz
+
; We only want to be here if we're in a dark cave.
ld a, [wTimeOfDayPalset]
cp DARKNESS_PALSET
@@ -937,16 +985,21 @@
push af
ld a, BANK(wBGPals1)
ldh [rSVBK], a
-; Ready for BGPD input...
+
+; Ready for BGPD input
ld a, (1 << rBGPI_AUTO_INCREMENT) palette PAL_BG_YELLOW
ldh [rBGPI], a
+
+; A cycle of 2 colors (0 2), updating every other vblank
ldh a, [hVBlankCounter]
and %10
- jr nz, .bit1set
- ld hl, wBGPals1 palette PAL_BG_YELLOW
+ jr nz, .color1
+
+; color0
+ ld hl, wBGPals1 palette PAL_BG_YELLOW color 0
jr .okay
-.bit1set
+.color1
ld hl, wBGPals1 palette PAL_BG_YELLOW color 1
.okay