Remove support for the original LCG random number generator (#5078)

include/battle.h

@@ -600,12 +600,10 @@ struct LostItem
     u16 stolen:1;
 };
 
-#if HQ_RANDOM == TRUE
 struct BattleVideo {
     u32 battleTypeFlags;
     rng_value_t rngSeed;
 };
-#endif
 
 enum BattleIntroStates
 {
@@ -707,12 +705,7 @@ 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/random.h

@@ -6,25 +6,21 @@
 #define ISO_RANDOMIZE1(val)(1103515245 * (val) + 24691)
 #define ISO_RANDOMIZE2(val)(1103515245 * (val) + 12345)
 
-/* Some functions have been added to support HQ_RANDOM.
+/* Some functions have been added to support Expansion's RNG implementation.
 *
-* If using HQ_RANDOM, you cannot call Random() in interrupt handlers safely.
-* AdvanceRandom() is provided to handle burning numbers in the VBlank handler
-* if you choose to do that, and can be used regardless of HQ_RANDOM setting.
+* LocalRandom(*val) provides a higher-quality replacement for uses of
+* ISO_RANDOMIZE in vanilla Emerald. You can use LocalRandomSeed(u32) to
+* create a local state.
+*
+* It is no longer possible to call Random() in interrupt handlers safely.
+* AdvanceRandom() is provided to handle burning numbers in VBlank handlers.
 * If you need to use random numbers in the VBlank handler, a local state
 * should be used instead.
 *
-* LocalRandom(*val) allows you to have local random states that are the same
-* type as the global states regardless of HQ_RANDOM setting, which is useful
-* if you want to be able to set them from or assign them to gRngValue.
-* LocalRandomSeed(u32) returns a properly seeded rng_value_t.
-*
-* Random2_32() was added to HQ_RANDOM because the output of the generator is
-* always 32 bits and Random()/Random2() are just wrappers in that mode. It is
-* also available in non-HQ mode for consistency.
+* Random2_32() was added, even though it is not used directly, because the
+* underlying RNG always outputs 32 bits.
 */
 
-#if HQ_RANDOM == TRUE
 struct Sfc32State {
     u32 a;
     u32 b;
@@ -70,40 +66,6 @@ static inline u16 Random2(void)
 }
 
 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);
-
-//Sets the initial seed value of the pseudorandom number generator
-void SeedRng(u16 seed);
-void SeedRng2(u16 seed);
-
-//Returns a 32-bit pseudorandom number
-#define Random32() (Random() | (Random() << 16))
-#define Random2_32() (Random2() | (Random2() << 16))
-
-static inline u16 LocalRandom(rng_value_t *val)
-{
-    *val = ISO_RANDOMIZE1(*val);
-    return *val >> 16;
-}
-
-static inline void AdvanceRandom(void)
-{
-    Random();
-}
-
-static inline rng_value_t LocalRandomSeed(u32 seed)
-{
-    return seed;
-}
-
-#endif
 
 extern rng_value_t gRngValue;
 extern rng_value_t gRng2Value;

src/battle_main.c

@@ -1692,15 +1692,9 @@ 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]++;

src/main.c

@@ -205,12 +205,9 @@ void SetMainCallback2(MainCallback callback)
 
 void StartTimer1(void)
 {
-    if (HQ_RANDOM)
-    {
-        REG_TM2CNT_L = 0;
-        REG_TM2CNT_H = TIMER_ENABLE | TIMER_COUNTUP;
-    }
 
+    REG_TM2CNT_L = 0;
+    REG_TM2CNT_H = TIMER_ENABLE | TIMER_COUNTUP;
     REG_TM1CNT_H = TIMER_ENABLE;
 }
 
@@ -218,24 +215,12 @@ void SeedRngAndSetTrainerId(void)
 {
     u32 val;
 
-    if (HQ_RANDOM)
-    {
-        REG_TM1CNT_H = 0;
-        REG_TM2CNT_H = 0;
-        val = ((u32)REG_TM2CNT_L) << 16;
-        val |= REG_TM1CNT_L;
-        SeedRng(val);
-        sTrainerId = Random();
-    }
-    else
-    {
-        // Do it exactly like it was originally done, including not stopping
-        // the timer beforehand.
-        val = REG_TM1CNT_L;
-        SeedRng((u16)val);
-        REG_TM1CNT_H = 0;
-        sTrainerId = val;
-    }
+    REG_TM1CNT_H = 0;
+    REG_TM2CNT_H = 0;
+    val = ((u32)REG_TM2CNT_L) << 16;
+    val |= REG_TM1CNT_L;
+    SeedRng(val);
+    sTrainerId = Random();
 }
 
 u16 GetGeneratedTrainerIdLower(void)
@@ -254,22 +239,16 @@ void EnableVCountIntrAtLine150(void)
 #ifdef BUGFIX
 static void SeedRngWithRtc(void)
 {
-    #if HQ_RANDOM == FALSE
-        u32 seed = RtcGetMinuteCount();
-        seed = (seed >> 16) ^ (seed & 0xFFFF);
-        SeedRng(seed);
-    #else
-        #define BCD8(x) ((((x) >> 4) & 0xF) * 10 + ((x) & 0xF))
-        u32 seconds;
-        struct SiiRtcInfo rtc;
-        RtcGetInfo(&rtc);
-        seconds =
-            ((HOURS_PER_DAY * RtcGetDayCount(&rtc) + BCD8(rtc.hour))
-            * MINUTES_PER_HOUR + BCD8(rtc.minute))
-            * SECONDS_PER_MINUTE + BCD8(rtc.second);
-        SeedRng(seconds);
-        #undef BCD8
-    #endif
+    #define BCD8(x) ((((x) >> 4) & 0xF) * 10 + ((x) & 0xF))
+    u32 seconds;
+    struct SiiRtcInfo rtc;
+    RtcGetInfo(&rtc);
+    seconds =
+        ((HOURS_PER_DAY * RtcGetDayCount(&rtc) + BCD8(rtc.hour))
+        * MINUTES_PER_HOUR + BCD8(rtc.minute))
+        * SECONDS_PER_MINUTE + BCD8(rtc.second);
+    SeedRng(seconds);
+    #undef BCD8
 }
 #endif
 

src/random.c

@@ -8,7 +8,6 @@
 rng_value_t gRngValue;
 rng_value_t gRng2Value;
 
-#if HQ_RANDOM == TRUE
 
 EWRAM_DATA static volatile bool8 sRngLoopUnlocked;
 
@@ -112,39 +111,6 @@ void AdvanceRandom(void)
 
 #define LOOP_RANDOM ((u16)(_SFC32_Next(state) >> 16))
 
-#else
-EWRAM_DATA static u32 sRandCount = 0;
-
-u16 Random(void)
-{
-    gRngValue = ISO_RANDOMIZE1(gRngValue);
-    sRandCount++;
-    return gRngValue >> 16;
-}
-
-void SeedRng(u16 seed)
-{
-    gRngValue = seed;
-}
-
-void SeedRng2(u16 seed)
-{
-    gRng2Value = seed;
-}
-
-u16 Random2(void)
-{
-    gRng2Value = ISO_RANDOMIZE1(gRng2Value);
-    return gRng2Value >> 16;
-}
-
-#define LOOP_RANDOM_START
-#define LOOP_RANDOM_END
-
-#define LOOP_RANDOM (Random())
-
-#endif
-
 #define SHUFFLE_IMPL \
     u32 tmp; \
     LOOP_RANDOM_START; \

test/random.c

@@ -196,13 +196,8 @@ TEST("RandomElement generates a uniform distribution")
 
 TEST("RandomUniform mul-based faster than mod-based (compile-time)")
 {
-    #if HQ_RANDOM == TRUE
-        const u32 expectedMulSum = 6;
-        const u32 expectedModSum = 4;
-    #else
-        const u32 expectedMulSum = 3;
-        const u32 expectedModSum = 4;
-    #endif
+    const u32 expectedMulSum = 6;
+    const u32 expectedModSum = 4;
     struct Benchmark mulBenchmark, modBenchmark;
     u32 mulSum = 0, modSum = 0;
 
@@ -234,13 +229,8 @@ TEST("RandomUniform mul-based faster than mod-based (compile-time)")
 
 TEST("RandomUniform mul-based faster than mod-based (run-time)")
 {
-    #if HQ_RANDOM == TRUE
-        const u32 expectedMulSum = 289;
-        const u32 expectedModSum = 205;
-    #else
-        const u32 expectedMulSum = 232;
-        const u32 expectedModSum = 249;
-    #endif
+    const u32 expectedMulSum = 289;
+    const u32 expectedModSum = 205;
     u32 i;
     struct Benchmark mulBenchmark, modBenchmark;
     u32 mulSum = 0, modSum = 0;
@@ -264,7 +254,6 @@ TEST("RandomUniform mul-based faster than mod-based (run-time)")
     EXPECT_EQ(modSum, expectedModSum);
 }
 
-#if HQ_RANDOM == TRUE
 TEST("Thumb and C SFC32 implementations produce the same results")
 {
     u32 thumbSum;
@@ -286,4 +275,3 @@ TEST("Thumb and C SFC32 implementations produce the same results")
 
     EXPECT_EQ(thumbSum, cSum);
 }
-#endif

test/test_runner_battle.c

@@ -35,20 +35,12 @@
 #define STATE gBattleTestRunnerState
 #define DATA gBattleTestRunnerState->data
 
-#if HQ_RANDOM == TRUE
 #define RNG_SEED_DEFAULT {0, 0, 0, 0}
 static inline bool32 RngSeedNotDefault(const rng_value_t *seed)
 {
     return (seed->a | seed->b | seed->c | seed->ctr) != 0;
 
 }
-#else
-#define RNG_SEED_DEFAULT 0x00000000
-static inline bool32 RngSeedNotDefault(const rng_value_t *seed)
-{
-    return *seed != RNG_SEED_DEFAULT;
-}
-#endif
 #undef Q_4_12
 #define Q_4_12(n) (s32)((n) * 4096)
 
@@ -1357,17 +1349,13 @@ static void CB2_BattleTest_NextParameter(void)
 
 static inline rng_value_t MakeRngValue(const u16 seed)
 {
-    #if HQ_RANDOM == TRUE
-        int i;
-        rng_value_t result = {0, 0, seed, 1};
-        for (i = 0; i < 16; i++)
-        {
+    int i;
+    rng_value_t result = {0, 0, seed, 1};
+    for (i = 0; i < 16; i++)
+    {
             _SFC32_Next(&result);
-        }
-        return result;
-    #else
-        return ISO_RANDOMIZE1(seed);
-    #endif
+    }
+    return result;
 }
 
 static void CB2_BattleTest_NextTrial(void)