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Merged
Eebit merged 2 commits into from
Aug 24, 2026
Merged

Decompile random number generation #65

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8b1aaf8
(random) Decompile random number generation
Eebit Aug 24, 2026
a36cc05
(random) Renames
Eebit Aug 24, 2026
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3 changes: 3 additions & 0 deletions config/YFEE01/arm9/delinks.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,9 @@ src/fade.cpp:
.text start:0x0201bc28 end:0x0201db38
.data start:0x020ce8f4 end:0x020ce974

src/random.cpp:
.text start:0x0201ff20 end:0x02020034

src/gamectrl.cpp:
.text start:0x020217b4 end:0x02022f4c
.data start:0x020cec44 end:0x020cf650
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10 changes: 5 additions & 5 deletions config/YFEE01/arm9/symbols.txt
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Expand Up @@ -1129,10 +1129,10 @@ func_0201fe40 kind:function(arm,size=0x2c) addr:0x0201fe40
func_0201fe6c kind:function(arm,size=0x54) addr:0x0201fe6c
LoadTexturePalette kind:function(arm,size=0x24) addr:0x0201fec0
func_0201fee4 kind:function(arm,size=0x3c) addr:0x0201fee4
func_0201ff20 kind:function(arm,size=0x90) addr:0x0201ff20
func_0201ffb0 kind:function(arm,size=0x10) addr:0x0201ffb0
func_0201ffc0 kind:function(arm,size=0x10) addr:0x0201ffc0
func_0201ffd0 kind:function(arm,size=0x3c) addr:0x0201ffd0
Random_Init kind:function(arm,size=0x90) addr:0x0201ff20
Random_SetState kind:function(arm,size=0x10) addr:0x0201ffb0
Random_GetState kind:function(arm,size=0x10) addr:0x0201ffc0
Random_Next kind:function(arm,size=0x3c) addr:0x0201ffd0
RollRN kind:function(arm,size=0x28) addr:0x0202000c
func_02020034 kind:function(arm,size=0x84) addr:0x02020034
func_020200b8 kind:function(arm,size=0x50) addr:0x020200b8
Expand Down Expand Up @@ -8559,7 +8559,7 @@ data_02194b2a kind:bss addr:0x02194b2a
data_02194b2c kind:bss addr:0x02194b2c
data_02195778 kind:bss addr:0x02195778
data_02196b2c kind:bss addr:0x02196b2c
data_02196e04 kind:bss addr:0x02196e04
gRandomSt kind:bss addr:0x02196e04
data_02196e0c kind:bss addr:0x02196e0c
data_02196f0c kind:bss addr:0x02196f0c
data_02196f10 kind:bss addr:0x02196f10
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2 changes: 1 addition & 1 deletion include/unknown_data.h
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Expand Up @@ -2902,7 +2902,7 @@ extern struct ProcCmd data_020cec14[];
// extern ??? data_02194b2c
// extern ??? data_02195778
// extern ??? data_02196b2c
// extern ??? data_02196e04
// extern ??? gRandomSt
// extern ??? data_02196e0c
// extern ??? data_02196f0c
// extern ??? data_02196f10
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8 changes: 4 additions & 4 deletions include/unknown_funcs.h
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Expand Up @@ -1150,10 +1150,10 @@ EC void LoadTextureImage(void *, u32, u32);
// EC ??? func_0201fe6c
EC void LoadTexturePalette(void *, u32, u32);
// EC ??? func_0201fee4
EC void func_0201ff20(void);
// EC ??? func_0201ffb0
EC s32 func_0201ffc0(void);
EC u32 func_0201ffd0(void);
EC void Random_Init(void);
// EC ??? Random_SetState
EC s32 Random_GetState(void);
EC u32 Random_Next(void);
EC s32 RollRN(s32, s32);
// EC ??? func_02020034
// EC ??? func_020200b8
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4 changes: 2 additions & 2 deletions src/face.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -578,7 +578,7 @@ void Face::DrawBlink(void)
return;
}

EC u32 func_0201ffd0(void);
EC u32 Random_Next(void);

void Face::UpdateMouth(void)
{
Expand Down Expand Up @@ -620,7 +620,7 @@ void Face::UpdateMouth(void)
return;
}

this->mouthCnt = (func_0201ffd0() & 7) + 1;
this->mouthCnt = (Random_Next() & 7) + 1;
this->mouthState = (this->mouthState + 1) & 3;

return;
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4 changes: 2 additions & 2 deletions src/gamectrl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1142,7 +1142,7 @@ EC void func_0202272c(ProcPtr proc)
data_02196f0c->state &= ~0x20000;
data_02196f0c->state &= ~0x100000;

data_02196f20->unk_194 = func_0201ffc0();
data_02196f20->unk_194 = Random_GetState();

return;
}
Expand Down Expand Up @@ -1370,7 +1370,7 @@ EC void func_02022bb0(ProcPtr proc)
gSoundManager->unk_a4->vfunc_3c(0x10, 0x48, 0);
}

func_0201ffd0();
Random_Next();

return;
}
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2 changes: 1 addition & 1 deletion src/hardware.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -125,7 +125,7 @@ void System_Init(void)
func_0200eecc();
func_0201f3dc();
rtc_init();
func_0201ff20();
Random_Init();
func_020217b4();

tmp = gpActiveScreenSt;
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2 changes: 1 addition & 1 deletion src/ov000/arena.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -664,7 +664,7 @@ u8 * arena::Arena::_021d80a4(Unit * unit, s32 arg_2)
break;

case 4:
if ((func_0201ffd0() & 1) != 0)
if ((Random_Next() & 1) != 0)
{
uVar1 = 4;
}
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6 changes: 3 additions & 3 deletions src/ov000/map_sequence.cpp
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Expand Up @@ -4691,7 +4691,7 @@ EC void func_ov000_021af044(map::ProcLink * param_1)
}

EC BOOL func_02012b8c(s32, void *);
EC void func_0201ffb0(s32);
EC void Random_SetState(s32);

EC void func_ov000_021af1bc(map::ProcLink * param_1)
{
Expand Down Expand Up @@ -4743,7 +4743,7 @@ EC void func_ov000_021af1bc(map::ProcLink * param_1)
gMapStateManager->cursor->isVisible = 0;
param_1->unk_3c = 0;
Proc_Goto(gMapLinkProc, 1, 0);
func_0201ffb0(gActionSt->unk_14);
Random_SetState(gActionSt->unk_14);
func_020a58b8(gActionSt, gMapStateManager->unk_08, 0x14);
return;
}
Expand Down Expand Up @@ -5085,7 +5085,7 @@ EC void ProcMind_ov000_021af79c(ProcEx * proc)
delete tempAction;
}

gActionSt->unk_14 = func_0201ffc0();
gActionSt->unk_14 = Random_GetState();

unit = GetUnit(gActionSt->unitId);

Expand Down
76 changes: 76 additions & 0 deletions src/random.cpp
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Original file line number Diff line number Diff line change
@@ -0,0 +1,76 @@
#include "global.h"

struct RandomState
{
/* 00 */ s32 unk_00; // unused??
/* 04 */ u32 state;
};

extern struct RandomState gRandomSt;

struct UnkStruct_Func_020ac374
{
/* 00 */ s32 unk_00;
/* 04 */ s32 unk_04;
/* 08 */ s32 unk_08;
/* 0C */ s32 unk_0c;
};

struct UnkStruct_Func_020ac420
{
/* 00 */ s32 unk_00;
/* 04 */ s32 unk_04;
/* 08 */ s32 unk_08;
};

EC s32 func_020ac374(struct UnkStruct_Func_020ac374 *);
EC s32 func_020ac420(struct UnkStruct_Func_020ac420 *);

EC void Random_Init(void)
{
struct UnkStruct_Func_020ac374 a;
struct UnkStruct_Func_020ac420 b;
s32 state;

if (func_020ac374(&a) == 0 && func_020ac420(&b) == 0)
{
state = a.unk_00 * 12 + a.unk_04;
state = state * 30 + a.unk_08;
state = state * 24 + b.unk_00;
state = state * 60 + b.unk_04;
state = state * 60 + b.unk_08;

gRandomSt.state = state;

return;
}

gRandomSt.state = 0x12345678;

return;
}

EC void Random_SetState(u32 state)
{
gRandomSt.state = state;
return;
}

EC u32 Random_GetState(void)
{
return gRandomSt.state;
}

EC u32 Random_Next(void)
{
u32 rand = gRandomSt.state ^ (0x65AC9365 >> (gRandomSt.state & 3));
gRandomSt.state = (rand >> 4) ^ (rand >> 3) ^ (rand << 3) ^ (rand << 4) ^ rand;
return gRandomSt.state & 0x7FFFFFFF;
}

EC s32 IntSys_Mod(s32, s32);

EC s32 RollRN(s32 param_1, s32 param_2)
{
return param_1 + IntSys_Mod(Random_Next() & 0x7fffffff, (param_2 - param_1) + 1);
}
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