Add some comments regarding 16-bit increment/decrement

audio/engine.asm

@@ -982,6 +982,7 @@ ApplyPitchSlide:
 	add hl, bc
 	add [hl]
 	ld [hl], a
+	; could have done "jr nc, .no_rollover / inc de / .no_rollover"
 	ld a, 0
 	adc e
 	ld e, a
@@ -1022,6 +1023,7 @@ ApplyPitchSlide:
 	ld a, [hl]
 	add a
 	ld [hl], a
+	; could have done "jr nc, .no_rollover / dec de / .no_rollover"
 	ld a, e
 	sbc 0
 	ld e, a

engine/gfx/pic_animation.asm

@@ -628,14 +628,16 @@ PokeAnim_ConvertAndApplyBitmask:
 	call AddNTimes
 	ld a, [wBoxAlignment]
 	and a
-	jr nz, .go
+	jr nz, .subtract
+	; hl += [wPokeAnimBitmaskCurCol]
 	ld a, [wPokeAnimBitmaskCurCol]
 	ld e, a
 	ld d, 0
 	add hl, de
-	jr .skip2
+	jr .done
 
-.go
+.subtract
+	; hl -= [wPokeAnimBitmaskCurCol]
 	ld a, [wPokeAnimBitmaskCurCol]
 	ld e, a
 	ld a, l
@@ -645,7 +647,7 @@ PokeAnim_ConvertAndApplyBitmask:
 	sbc 0
 	ld h, a
 
-.skip2
+.done
 	ret
 
 .UnusedSizeData: ; unreferenced