Optional high-quality RNG

include/battle.h

@@ -15,6 +15,7 @@
 #include "pokeball.h"
 #include "battle_debug.h"
 #include "battle_dynamax.h"
+#include "random.h" // for rng_value_t
 
 // Used to exclude moves learned temporarily by Transform or Mimic
 #define MOVE_IS_PERMANENT(battler, moveSlot)                        \
@@ -580,6 +581,13 @@ struct LostItem
     u16 stolen:1;
 };
 
+#if HQ_RANDOM == TRUE
+struct BattleVideo {
+    u32 battleTypeFlags;
+    rng_value_t rngSeed;
+};
+#endif
+
 struct BattleStruct
 {
     u8 turnEffectsTracker;
@@ -651,7 +659,12 @@ struct BattleStruct
     u16 lastTakenMoveFrom[MAX_BATTLERS_COUNT][MAX_BATTLERS_COUNT]; // a 2-D array [target][attacker]
     union {
         struct LinkBattlerHeader linkBattlerHeader;
+
+        #if HQ_RANDOM == FALSE
         u32 battleVideo[2];
+        #else
+        struct BattleVideo battleVideo;
+        #endif
     } multiBuffer;
     u8 wishPerishSongState;
     u8 wishPerishSongBattlerId;

include/config.h

@@ -79,5 +79,6 @@
 #define EXPANSION_INTRO              TRUE    // If TRUE, a custom RHH intro will play after the vanilla copyright screen.
 #define POKEDEX_PLUS_HGSS            FALSE   // If TRUE, enables the custom HGSS style Pokedex.
 #define SUMMARY_SCREEN_NATURE_COLORS TRUE    // If TRUE, nature-based stat boosts and reductions will be red and blue in the summary screen.
+#define HQ_RANDOM                    TRUE    // If TRUE, replaces the default RNG with an implementation of SFC32 RNG. May break code that relies on RNG.
 
 #endif // GUARD_CONFIG_H

include/contest.h

@@ -3,6 +3,7 @@
 
 #include "palette.h"
 #include "constants/contest.h"
+#include "random.h" // for rng_value_t
 
 enum
 {
@@ -327,7 +328,7 @@ extern struct ContestResources *gContestResources;
 extern struct ContestWinner gCurContestWinner;
 extern u8 gCurContestWinnerIsForArtist;
 extern u8 gCurContestWinnerSaveIdx;
-extern u32 gContestRngValue;
+extern rng_value_t gContestRngValue;
 
 // contest.c
 void ResetLinkContestBoolean(void);

include/random.h

@@ -1,20 +1,88 @@
 #ifndef GUARD_RANDOM_H
 #define GUARD_RANDOM_H
 
-extern u32 gRngValue;
-extern u32 gRng2Value;
+// The number 1103515245 comes from the example implementation of rand and srand
+// in the ISO C standard.
+#define ISO_RANDOMIZE1(val)(1103515245 * (val) + 24691)
+#define ISO_RANDOMIZE2(val)(1103515245 * (val) + 12345)
+
+/* Notes about new functions:
+* If using HQ_RANDOM, you MUST call AdvanceRandom() in VBlank handlers.
+* If you do not, you risk corruption of the RNG state.
+* LocalRandom(*val) adapts to either choice of RNG implementation.
+* Other new functions should be self-explanatory.
+*/
+
+#if HQ_RANDOM == TRUE
+struct Sfc32State {
+    u32 a;
+    u32 b;
+    u32 c;
+    u32 ctr;
+};
+
+typedef struct Sfc32State rng_value_t;
+
+#define RNG_VALUE_EMPTY {}
+
+// Calling this function directly is discouraged.
+// Use LocalRandom() instead.
+static inline u32 _SFC32_Next(struct Sfc32State *state)
+{
+    const u32 result = state->a + state->b + state->ctr++;
+    state->a = state->b ^ (state->b >> 9);
+    state->b = state->c * 9;
+    state->c = result + ((state->c << 21) | (state->c >> 11));
+    return result;
+}
+
+static inline u16 LocalRandom(rng_value_t *val)
+{
+    return _SFC32_Next(val) >> 16;
+}
+
+u32 Random32(void);
+u32 Random2_32(void);
+
+static inline u16 Random(void)
+{
+    return Random32() >> 16;
+}
+
+static inline u16 Random2(void)
+{
+    return Random2_32() >> 16;
+}
+
+void AdvanceRandom(void);
+#else
+typedef u32 rng_value_t;
+
+#define RNG_VALUE_EMPTY 0
 
 //Returns a 16-bit pseudorandom number
 u16 Random(void);
 u16 Random2(void);
 
 //Returns a 32-bit pseudorandom number
 #define Random32() (Random() | (Random() << 16))
+#define Random2_32() (Random2() | (Random2() << 16))
 
-// The number 1103515245 comes from the example implementation of rand and srand
-// in the ISO C standard.
-#define ISO_RANDOMIZE1(val)(1103515245 * (val) + 24691)
-#define ISO_RANDOMIZE2(val)(1103515245 * (val) + 12345)
+static inline u16 LocalRandom(rng_value_t *val)
+{
+    *val = ISO_RANDOMIZE1(*val);
+    return *val >> 16;
+}
+
+static inline void AdvanceRandom(void)
+{
+    Random();
+}
+
+#endif
+
+extern rng_value_t gRngValue;
+extern rng_value_t gRng2Value;
 
 //Sets the initial seed value of the pseudorandom number generator
 void SeedRng(u16 seed);

include/recorded_battle.h

@@ -2,6 +2,7 @@
 #define GUARD_RECORDED_BATTLE_H
 
 #include "constants/battle.h"
+#include "random.h" // for rng_value_t
 
 #define BATTLER_RECORD_SIZE 664
 
@@ -13,7 +14,7 @@ struct RecordedBattleSave
     u8 playersGender[MAX_BATTLERS_COUNT];
     u32 playersTrainerId[MAX_BATTLERS_COUNT];
     u8 playersLanguage[MAX_BATTLERS_COUNT];
-    u32 rngSeed;
+    rng_value_t rngSeed;
     u32 battleFlags;
     u8 playersBattlers[MAX_BATTLERS_COUNT];
     u16 opponentA;
@@ -49,8 +50,8 @@ enum
     RECORDED_ITEM_MOVE,
 };
 
-extern u32 gRecordedBattleRngSeed;
-extern u32 gBattlePalaceMoveSelectionRngValue;
+extern rng_value_t gRecordedBattleRngSeed;
+extern rng_value_t gBattlePalaceMoveSelectionRngValue;
 extern u8 gRecordedBattleMultiplayerId;
 
 #define B_RECORD_MODE_RECORDING 1

include/test/battle.h

@@ -842,7 +842,7 @@ struct moveWithPP {
 void OpenPokemon(u32 sourceLine, u32 side, u32 species);
 void ClosePokemon(u32 sourceLine);
 
-void RNGSeed_(u32 sourceLine, u32 seed);
+void RNGSeed_(u32 sourceLine, rng_value_t seed);
 void AIFlags_(u32 sourceLine, u32 flags);
 void AILogScores(u32 sourceLine);
 void Gender_(u32 sourceLine, u32 gender);

src/battle_controller_link_opponent.c

@@ -28,6 +28,7 @@
 #include "constants/songs.h"
 #include "constants/trainers.h"
 #include "recorded_battle.h"
+#include "random.h" // for rng_value_t
 
 static void LinkOpponentHandleLoadMonSprite(u32 battler);
 static void LinkOpponentHandleSwitchInAnim(u32 battler);

src/battle_controller_link_partner.c

@@ -28,6 +28,7 @@
 #include "constants/songs.h"
 #include "constants/trainers.h"
 #include "recorded_battle.h"
+#include "random.h" // for rng_value_t
 
 static void LinkPartnerHandleLoadMonSprite(u32 battler);
 static void LinkPartnerHandleSwitchInAnim(u32 battler);

src/battle_main.c

@@ -1713,9 +1713,16 @@ static void CB2_HandleStartMultiBattle(void)
     case 8:
         if (IsLinkTaskFinished())
         {
+            #if HQ_RANDOM == TRUE
+            struct BattleVideo *ptr = &gBattleStruct->multiBuffer.battleVideo;
+            ptr->battleTypeFlags = gBattleTypeFlags;
+            ptr->rngSeed = gRecordedBattleRngSeed;
+            #else
             u32 *ptr = gBattleStruct->multiBuffer.battleVideo;
             ptr[0] = gBattleTypeFlags;
             ptr[1] = gRecordedBattleRngSeed; // UB: overwrites berry data
+            #endif
+
             SendBlock(BitmaskAllOtherLinkPlayers(), ptr, sizeof(gBattleStruct->multiBuffer.battleVideo));
             gBattleCommunication[MULTIUSE_STATE]++;
         }
@@ -2053,7 +2060,7 @@ void VBlankCB_Battle(void)
 {
     // Change gRngSeed every vblank unless the battle could be recorded.
     if (!(gBattleTypeFlags & (BATTLE_TYPE_LINK | BATTLE_TYPE_FRONTIER | BATTLE_TYPE_RECORDED)))
-        Random();
+        AdvanceRandom();
 
     SetGpuReg(REG_OFFSET_BG0HOFS, gBattle_BG0_X);
     SetGpuReg(REG_OFFSET_BG0VOFS, gBattle_BG0_Y);

src/contest.c

@@ -358,7 +358,7 @@ EWRAM_DATA bool8 gCurContestWinnerIsForArtist = 0;
 EWRAM_DATA u8 gCurContestWinnerSaveIdx = 0;
 
 // IWRAM common vars.
-u32 gContestRngValue;
+rng_value_t gContestRngValue;
 
 extern const u8 gText_LinkStandby4[];
 extern const u8 gText_BDot[];
@@ -1709,7 +1709,7 @@ static void Task_AppealSetup(u8 taskId)
     if (++gTasks[taskId].data[0] > 19)
     {
         eContest.turnNumber = 0;
-        eContest.unusedRng = gRngValue;
+        eContest.unusedRng = 0;
         if ((gLinkContestFlags & LINK_CONTEST_FLAG_IS_LINK) && IsPlayerLinkLeader())
         {
             s32 i;
@@ -6109,4 +6109,3 @@ void StripPlayerAndMonNamesForLinkContest(struct ContestPokemon *mon, s32 langua
         name[PLAYER_NAME_LENGTH] = EOS;
     }
 }
-

src/contest_util.c

@@ -2655,8 +2655,7 @@ void GenerateContestRand(void)
 
     if (gLinkContestFlags & LINK_CONTEST_FLAG_IS_LINK)
     {
-        gContestRngValue = ISO_RANDOMIZE1(gContestRngValue);
-        random = gContestRngValue >> 16;
+        random = LocalRandom(&gContestRngValue);
         result = &gSpecialVar_Result;
     }
     else
@@ -2669,8 +2668,7 @@ void GenerateContestRand(void)
 
 u16 GetContestRand(void)
 {
-    gContestRngValue = ISO_RANDOMIZE1(gContestRngValue);
-    return gContestRngValue >> 16;
+    return LocalRandom(&gContestRngValue);
 }
 
 bool8 LinkContestWaitForConnection(void)

src/debug.c

@@ -2144,7 +2144,7 @@ static void DebugAction_Util_Player_Gender(u8 taskId)
 
 static void DebugAction_Util_Player_Id(u8 taskId)
 {
-    u32 trainerId = ((Random() << 16) | Random());
+    u32 trainerId = Random32();
     SetTrainerId(trainerId, gSaveBlock2Ptr->playerTrainerId);
     Debug_DestroyMenu_Full(taskId);
     ScriptContext_Enable();

src/load_save.c

@@ -127,7 +127,7 @@ void MoveSaveBlocks_ResetHeap(void)
     gMain.vblankCallback = vblankCB;
 
     // create a new encryption key
-    encryptionKey = (Random() << 16) + (Random());
+    encryptionKey = Random32();
     ApplyNewEncryptionKeyToAllEncryptedData(encryptionKey);
     gSaveBlock2Ptr->encryptionKey = encryptionKey;
 }

src/lottery_corner.c

@@ -23,9 +23,7 @@ static u8 GetMatchingDigits(u16, u16);
 
 void ResetLotteryCorner(void)
 {
-    u16 rand = Random();
-
-    SetLotteryNumber((Random() << 16) | rand);
+    SetLotteryNumber(Random32());
     VarSet(VAR_POKELOT_PRIZE_ITEM, 0);
 }
 

src/main.c

@@ -373,7 +373,7 @@ static void VBlankIntr(void)
     TryReceiveLinkBattleData();
 
     if (!gMain.inBattle || !(gBattleTypeFlags & (BATTLE_TYPE_LINK | BATTLE_TYPE_FRONTIER | BATTLE_TYPE_RECORDED)))
-        Random();
+        AdvanceRandom();
 
     UpdateWirelessStatusIndicatorSprite();