diff options
Diffstat (limited to 'home')
| -rwxr-xr-x | home/items.asm | 8 | ||||
| -rw-r--r-- | home/random.asm | 69 | ||||
| -rwxr-xr-x | home/tables.asm | 27 |
3 files changed, 100 insertions, 4 deletions
diff --git a/home/items.asm b/home/items.asm index 496b685..0edd72b 100755 --- a/home/items.asm +++ b/home/items.asm @@ -10,17 +10,17 @@ AddItemToInventory:: ; 3259 ; function to add an item (in varying quantities) to the player's bag or PC box
; INPUT:
; HL = address of inventory (either wNumBagItems or wNumBoxItems)
-; [wcd76] = item ID
+; [wCurItem] = item ID
; [wItemQuantity] = item quantity
; sets carry flag if successful, unsets carry flag if unsuccessful
push bc
ldh a, [hROMBank]
push af
- ld a, BANK(AddItemToInventory_)
+ ld a, BANK(_ReceiveItem)
call Bankswitch
push hl
push de
- call AddItemToInventory_
+ call _ReceiveItem
pop de
pop hl
pop bc
@@ -41,7 +41,7 @@ GiveItem:: ; Return carry on success.
ld a, b
ld [wce37], a
- ld [wcd76], a
+ ld [wCurItem], a
ld a, c
ld [wItemQuantity], a
ld hl, wNumBagItems
diff --git a/home/random.asm b/home/random.asm new file mode 100644 index 0000000..5ca7c78 --- /dev/null +++ b/home/random.asm @@ -0,0 +1,69 @@ +include "constants.asm" + +if DEBUG +SECTION "Random Number Generation", ROM0 [$3270] +else +SECTION "Random Number Generation", ROM0 [$3234] +endc + +Random:: +; A simple hardware-based random number generator (RNG). + +; Two random numbers are generated by adding and subtracting +; the divider to the respective values every time it's called. + +; The divider is a register that increments at a rate of 16384Hz. +; For comparison, the Game Boy operates at a clock speed of 4.2MHz. + +; This implementation also takes the current scanline as read from rLY +; and adds it nybble-swapped to the value of the divider. The unswapped +; value of rLY is also added to the value that's subtracted. + +; Additionally, an equivalent function is executed in VBlank. + +; This leaves a with the value in hRandomSub. + + push bc + + ldh a, [rLY] + ld c, a + swap a + ld b, a + ldh a, [rDIV] + adc b + ld b, a + ldh a, [hRandomAdd] + adc b + ldh [hRandomAdd], a + + ldh a, [rLY] + swap a + ld b, a + ldh a, [rDIV] + adc b + adc c + ld b, a + ldh a, [hRandomSub] + sbc b + ldh [hRandomSub], a + + pop bc + ret + +BattleRandom:: +; _BattleRandom lives in another bank. + +; It handles all RNG calls in the battle engine, allowing +; link battles to remain in sync using a shared PRNG. + ldh a, [hROMBank] + push af + ld a, BANK(_BattleRandom) + call Bankswitch + + call _BattleRandom + + ld [wPredefHL + 1], a + pop af + call Bankswitch + ld a, [wPredefHL + 1] + ret diff --git a/home/tables.asm b/home/tables.asm new file mode 100755 index 0000000..dc9cebe --- /dev/null +++ b/home/tables.asm @@ -0,0 +1,27 @@ +INCLUDE "constants.asm"
+
+SECTION "FindItemInTable", ROM0[$35F8]
+
+; find value a from table hl with row length de
+; returns carry and row index b if successful
+FindItemInTable: ; 00:35F8
+ ld b, 0
+ ld c, a
+
+.loop
+ ld a, [hl]
+ cp -1
+ jr z, .fail
+ cp c
+ jr z, .success
+ inc b
+ add hl, de
+ jr .loop
+
+.fail
+ and a
+ ret
+
+.success
+ scf
+ ret
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