commenting for DecrementPP from DarkShikari

hg-commit-id: 4fc5d67d4912

1 files changed, 34 insertions, 23 deletions

diff --git a/common.asm b/common.asm
index ba082d97..ee63f3d5 100644
--- a/common.asm
+++ b/common.asm
@@ -44432,32 +44432,43 @@ SECTION "bank1A",DATA,BANK[$1A]
 
 DecrementPP: ; 0x68000
 ; after using a move, decrement pp in battle and (if not transformed?) in party
-	ld a,[de]
-	cp a,STRUGGLE
-	ret z
-	ld hl,$D062
-	ld a,[hli]
-	and a,7
-	ret nz
-	bit 6,[hl]
-	ret nz
-	ld hl,$D02D ; PP of first move (in battle)
+	ld a, [de]
+	cp a, STRUGGLE
+	ret z                ; if the pokemon is using "struggle", there's nothing to do
+                         ; we don't decrement PP for "struggle"
+	ld hl, $D062
+	ld a, [hli]          ; load the $D062 pokemon status flags and increment hl to load the
+                         ; $D063 status flags later
+	and a, 7             ; check to see if bits 0, 1, or 2 are set
+	ret nz               ; if any of these statuses are true, don't decrement PP
+	bit 6, [hl]          ; check 6th bit status flag on $D063
+	ret nz               ; and return if it is set
+	ld hl, $D02D         ; PP of first move (in battle)
 	call .DecrementPP\@
 
-	ld a,[$D064]
-	bit 3,a ; XXX transform status?
-	ret nz
-
-	ld hl,$D188 ; PP of first move (in party)
-	ld a,[$CC2F] ; which mon in party is active
-	ld bc,$2C
-	call AddNTimes
+	ld a, [$D064]        ; load pokemon status bits?
+	bit 3, a             ; XXX transform status?
+	ret nz               ; If it is, return.  Pokemon Red stores the "current pokemon's" PP
+                         ; separately from the "Pokemon in your party's" PP.  This is
+                         ; duplication -- in all cases *other* than Pokemon with Transform.
+                         ; Normally, this means we have to go on and make the same     
+                         ; modification to the "party's pokemon" PP that we made to the
+                         ; "current pokemon's" PP.  But, if we're dealing with a Transformed
+                         ; Pokemon, it has separate PP for the move set that it copied from
+                         ; its opponent, which is *not* the same as its real PP as part of your
+                         ; party.  So we return, and don't do that part.
+
+	ld hl, $D188         ; PP of first move (in party)
+	ld a, [$CC2F]        ; which mon in party is active
+	ld bc, $2C           ; XXX probably size of party pokemon's data structure
+	call AddNTimes       ; calculate address of the mon to modify
 .DecrementPP\@
-	ld a,[$CC2E] ; which move (0, 1, 2, 3) did we use?
-	ld c,a
-	ld b,0
-	add hl,bc
-	dec [hl] ; Decrement PP
+	ld a, [$CC2E]        ; which move (0, 1, 2, 3) did we use?
+	ld c, a
+	ld b, 0
+	add hl ,bc           ; calculate the address in memory of the PP we need to decrement
+                         ; based on the move chosen.
+	dec [hl]             ; Decrement PP
 	ret
 ; 0x6802f