diff options
Diffstat (limited to 'home/random.asm')
| -rw-r--r-- | home/random.asm | 63 |
1 files changed, 14 insertions, 49 deletions
diff --git a/home/random.asm b/home/random.asm index ae39f439..f96718b2 100644 --- a/home/random.asm +++ b/home/random.asm @@ -1,84 +1,49 @@ -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. - +Random:: ; 30a2 (0:30a2) push bc - ld a, [rDIV] ld b, a - ld a, [hRandomAdd] + ld a, [hRandom] adc b - ld [hRandomAdd], a - + ld [hRandom], 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. +BattleRandom:: ld a, [hROMBank] push af - ld a, BANK(_BattleRandom) + ld a, BANK(BattleRandom_) rst Bankswitch - - call _BattleRandom - - ld [PredefTemp + 1], a + call BattleRandom_ + ld [wPredefHLBuffer + 1], a pop af rst Bankswitch - ld a, [PredefTemp + 1] + ld a, [wPredefHLBuffer + 1] ret -; 2fb1 - - -RandomRange:: ; 2fb1 -; Return a random number between 0 and a (non-inclusive). +RandomRange:: push bc ld c, a - - ; b = $100 % c xor a sub c -.mod +.asm_30cb sub c - jr nc, .mod + jr nc, .asm_30cb add c ld b, a - - ; Get a random number - ; from 0 to $ff - b. push bc -.loop +.asm_30d1 call Random - ld a, [hRandomAdd] + ld a, [hRandom] ld c, a add b - jr c, .loop + jr c, .asm_30d1 ld a, c pop bc - call SimpleDivide - pop bc ret -; 2fcb |