From edf939a07be9e0553a3ef91dd66291806dd3ad50 Mon Sep 17 00:00:00 2001 From: yenatch Date: Sun, 8 Sep 2013 02:47:52 -0400 Subject: [PATCH] split Random into common/random.asm --- common/random.asm | 76 +++++++++++++++++++++++++++++++++++++++++++++++ main.asm | 76 +---------------------------------------------- 2 files changed, 77 insertions(+), 75 deletions(-) create mode 100644 common/random.asm diff --git a/common/random.asm b/common/random.asm new file mode 100644 index 000000000..0f46da9e4 --- /dev/null +++ b/common/random.asm @@ -0,0 +1,76 @@ +Random: ; 2f8c +; 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. + +; Additionally, an equivalent function is executed in VBlank. + +; This leaves a with the value in hRandomSub. + + push bc + + ld a, [rDIV] + ld b, a + ld a, [hRandomAdd] + adc b + ld [hRandomAdd], a + + ld a, [rDIV] + ld b, a + ld a, [hRandomSub] + sbc b + ld [hRandomSub], a + + pop bc + ret +; 2f9f + +BattleRandom: ; 2f9f +; _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. + + ld a, [hROMBank] + push af + ld a, BANK(_BattleRandom) + rst Bankswitch + + call _BattleRandom + + ld [$cfb6], a + pop af + rst Bankswitch + ld a, [$cfb6] + ret +; 2fb1 + + +Function2fb1: ; 2fb1 + push bc + ld c, a + xor a + sub c +.asm_2fb5 + sub c + jr nc, .asm_2fb5 + add c + ld b, a + push bc +.asm_2fbb + call Random + ld a, [hRandomAdd] + ld c, a + add b + jr c, .asm_2fbb + ld a, c + pop bc + call SimpleDivide + pop bc + ret +; 2fcb + diff --git a/main.asm b/main.asm index b514c8fbb..1d57996ea 100644 --- a/main.asm +++ b/main.asm @@ -810,82 +810,8 @@ Function2f3e: ; 2f3e INCLUDE "common/item.asm" +INCLUDE "common/random.asm" -Random: ; 2f8c -; 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. - -; Additionally, an equivalent function is executed in VBlank. - -; This leaves a with the value in hRandomSub. - - push bc - - ld a, [rDIV] - ld b, a - ld a, [hRandomAdd] - adc b - ld [hRandomAdd], a - - ld a, [rDIV] - ld b, a - ld a, [hRandomSub] - sbc b - ld [hRandomSub], a - - pop bc - ret -; 2f9f - -BattleRandom: ; 2f9f -; _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. - - ld a, [hROMBank] - push af - ld a, BANK(_BattleRandom) - rst Bankswitch - - call _BattleRandom - - ld [$cfb6], a - pop af - rst Bankswitch - ld a, [$cfb6] - ret -; 2fb1 - - -Function2fb1: ; 2fb1 - push bc - ld c, a - xor a - sub c -.asm_2fb5 - sub c - jr nc, .asm_2fb5 - add c - ld b, a - push bc -.asm_2fbb - call Random - ld a, [hRandomAdd] - ld c, a - add b - jr c, .asm_2fbb - ld a, c - pop bc - call SimpleDivide - pop bc - ret -; 2fcb GetSRAMBank: ; 2fcb ; load sram bank a