ref: c44b52577b6ecb770ff9e7d7d67c11ed909b9642
parent: 0152e339095e928e689e67dd0da029fde756d853
author: IIMarckus <iimarckus@gmail.com>
date: Mon Dec 12 14:47:20 EST 2011
Add random number generation functions. hg-commit-id: e7d865799d77
--- a/constants.asm
+++ b/constants.asm
@@ -112,7 +112,11 @@
W_ENEMYMON6MOVE3 EQU $D98A
+H_RAND1 EQU $FFD3
+H_RAND2 EQU $FFD4
+
; hardware registers, from the pandocs http://nocash.emubase.de/pandocs.htm
+rDIV EQU $FF04
rBGP EQU $FF47
rOBP0 EQU $FF48
rOBP1 EQU $FF49
--- a/pokered.asm
+++ b/pokered.asm
@@ -1121,8 +1121,22 @@
ld c,3
jp DelayFrames
-INCBIN "baserom.gbc",$3DDC,$3E6D - $3DDC
+INCBIN "baserom.gbc",$3DDC,$3E5C - $3DDC
+GenRandom: ; 3E5C
+; store a random 8-bit value in a
+ push hl
+ push de
+ push bc
+ ld b,BANK(GenRandom_)
+ ld hl,GenRandom_
+ call Bankswitch
+ ld a,[H_RAND1]
+ pop bc
+ pop de
+ pop hl
+ ret
+
Predef: ; 3E6D
; runs a predefined ASM command, where the command ID is read from $D0B7
@@ -3558,7 +3572,7 @@
call $62B4
jp c,$6581
Next625F:
- call $3E5C
+ call GenRandom
srl a
jr c,Next6278
and 3
@@ -3729,8 +3743,22 @@
ShrinkPic2:
INCBIN "pic/trainer/shrink2.pic"
-INCBIN "baserom.gbc",$13074,$13AA0-$13074
+INCBIN "baserom.gbc",$13074,$13A8F-$13074
+GenRandom_: ; 7A8F
+; generate a random 16-bit integer and store it at $FFD3,$FFD4
+ ld a,[rDIV]
+ ld b,a
+ ld a,[H_RAND1]
+ adc b
+ ld [H_RAND1],a
+ ld a,[rDIV]
+ ld b,a
+ ld a,[H_RAND2]
+ sbc b
+ ld [H_RAND2],a
+ ret
+
SECTION "bank5",DATA,BANK[$5]
INCBIN "baserom.gbc",$14000,$4000
@@ -5635,7 +5663,7 @@
ld a,[hli]
ld h,[hl]
ld l,a
- call $3E5C
+ call GenRandom
jp [hl]
TrainerAIPointers: ; 655C