From 03b465c5e2f099c12d0816e89e008c98ccbffd8a Mon Sep 17 00:00:00 2001
From: wheremyfoodat <44909372+wheremyfoodat@users.noreply.github.com>
Date: Sat, 20 Feb 2021 00:58:41 +0200
Subject: Fix edge case in the division engine, fix edge case in the CPU
 (#1003)

* Fixed division edge case: Div64/32 and Div64/64 set the remainder to 0 if dividend == INT64_MIN && divisor == -1

* Fixed CPU edge case where ARM9 ALU ops would switch to Thumb even when they shouldn't

* Only clear the lowest bit of the jump address in ALU ops with rd==15 (on recommendation of RSDuck)
---
 src/ARMInterpreter_ALU.cpp | 24 ++++++++++++------------
 src/NDS.cpp                |  2 ++
 2 files changed, 14 insertions(+), 12 deletions(-)

(limited to 'src')

diff --git a/src/ARMInterpreter_ALU.cpp b/src/ARMInterpreter_ALU.cpp
index 2095432..39d14a9 100644
--- a/src/ARMInterpreter_ALU.cpp
+++ b/src/ARMInterpreter_ALU.cpp
@@ -290,7 +290,7 @@ void A_##x##_REG_ROR_REG(ARM* cpu) \
     if (c) cpu->AddCycles_CI(c); else cpu->AddCycles_C(); \
     if (((cpu->CurInstr>>12) & 0xF) == 15) \
     { \
-        cpu->JumpTo(res); \
+        cpu->JumpTo(res & ~1); \
     } \
     else \
     { \
@@ -321,7 +321,7 @@ A_IMPLEMENT_ALU_OP(AND,_S)
     if (c) cpu->AddCycles_CI(c); else cpu->AddCycles_C(); \
     if (((cpu->CurInstr>>12) & 0xF) == 15) \
     { \
-        cpu->JumpTo(res); \
+        cpu->JumpTo(res & ~1); \
     } \
     else \
     { \
@@ -352,7 +352,7 @@ A_IMPLEMENT_ALU_OP(EOR,_S)
     if (c) cpu->AddCycles_CI(c); else cpu->AddCycles_C(); \
     if (((cpu->CurInstr>>12) & 0xF) == 15) \
     { \
-        cpu->JumpTo(res); \
+        cpu->JumpTo(res & ~1); \
     } \
     else \
     { \
@@ -385,7 +385,7 @@ A_IMPLEMENT_ALU_OP(SUB,)
     if (c) cpu->AddCycles_CI(c); else cpu->AddCycles_C(); \
     if (((cpu->CurInstr>>12) & 0xF) == 15) \
     { \
-        cpu->JumpTo(res); \
+        cpu->JumpTo(res & ~1); \
     } \
     else \
     { \
@@ -418,7 +418,7 @@ A_IMPLEMENT_ALU_OP(RSB,)
     if (c) cpu->AddCycles_CI(c); else cpu->AddCycles_C(); \
     if (((cpu->CurInstr>>12) & 0xF) == 15) \
     { \
-        cpu->JumpTo(res); \
+        cpu->JumpTo(res & ~1); \
     } \
     else \
     { \
@@ -451,7 +451,7 @@ A_IMPLEMENT_ALU_OP(ADD,)
     if (c) cpu->AddCycles_CI(c); else cpu->AddCycles_C(); \
     if (((cpu->CurInstr>>12) & 0xF) == 15) \
     { \
-        cpu->JumpTo(res); \
+        cpu->JumpTo(res & ~1); \
     } \
     else \
     { \
@@ -486,7 +486,7 @@ A_IMPLEMENT_ALU_OP(ADC,)
     if (c) cpu->AddCycles_CI(c); else cpu->AddCycles_C(); \
     if (((cpu->CurInstr>>12) & 0xF) == 15) \
     { \
-        cpu->JumpTo(res); \
+        cpu->JumpTo(res & ~1); \
     } \
     else \
     { \
@@ -521,7 +521,7 @@ A_IMPLEMENT_ALU_OP(SBC,)
     if (c) cpu->AddCycles_CI(c); else cpu->AddCycles_C(); \
     if (((cpu->CurInstr>>12) & 0xF) == 15) \
     { \
-        cpu->JumpTo(res); \
+        cpu->JumpTo(res & ~1); \
     } \
     else \
     { \
@@ -600,7 +600,7 @@ A_IMPLEMENT_ALU_TEST(CMN,)
     if (c) cpu->AddCycles_CI(c); else cpu->AddCycles_C(); \
     if (((cpu->CurInstr>>12) & 0xF) == 15) \
     { \
-        cpu->JumpTo(res); \
+        cpu->JumpTo(res & ~1); \
     } \
     else \
     { \
@@ -629,7 +629,7 @@ A_IMPLEMENT_ALU_OP(ORR,_S)
     if (c) cpu->AddCycles_CI(c); else cpu->AddCycles_C(); \
     if (((cpu->CurInstr>>12) & 0xF) == 15) \
     { \
-        cpu->JumpTo(b); \
+        cpu->JumpTo(b & ~1); \
     } \
     else \
     { \
@@ -673,7 +673,7 @@ void A_MOV_REG_LSL_IMM_DBG(ARM* cpu)
     if (c) cpu->AddCycles_CI(c); else cpu->AddCycles_C(); \
     if (((cpu->CurInstr>>12) & 0xF) == 15) \
     { \
-        cpu->JumpTo(res); \
+        cpu->JumpTo(res & ~1); \
     } \
     else \
     { \
@@ -703,7 +703,7 @@ A_IMPLEMENT_ALU_OP(BIC,_S)
     if (c) cpu->AddCycles_CI(c); else cpu->AddCycles_C(); \
     if (((cpu->CurInstr>>12) & 0xF) == 15) \
     { \
-        cpu->JumpTo(b); \
+        cpu->JumpTo(b & ~1); \
     } \
     else \
     { \
diff --git a/src/NDS.cpp b/src/NDS.cpp
index 6c41cb5..7313c2a 100644
--- a/src/NDS.cpp
+++ b/src/NDS.cpp
@@ -1758,6 +1758,7 @@ void DivDone(u32 param)
             else if (num == -0x8000000000000000 && den == -1)
             {
                 *(s64*)&DivQuotient[0] = 0x8000000000000000;
+                *(s64*)&DivRemainder[0] = 0;
             }
             else
             {
@@ -1779,6 +1780,7 @@ void DivDone(u32 param)
             else if (num == -0x8000000000000000 && den == -1)
             {
                 *(s64*)&DivQuotient[0] = 0x8000000000000000;
+                *(s64*)&DivRemainder[0] = 0;
             }
             else
             {
-- 
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