From eeb92580c6fc8607f914e771095834b234a81f5b Mon Sep 17 00:00:00 2001
From: Martin Perner <martin@perner.cc>
Date: Tue, 9 Nov 2010 16:56:57 +0100
Subject: [PATCH] sim: bugfix for overflow and so ...

---
 3b_sim/ccpu.cpp          | 6 ++++--
 3c_disasm/instr/cmp.cpp  | 2 +-
 3c_disasm/instr/cmpi.cpp | 5 +++--
 3c_disasm/instr/sub.cpp  | 2 +-
 3c_disasm/instr/subi.cpp | 2 +-
 5 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/3b_sim/ccpu.cpp b/3b_sim/ccpu.cpp
index 04dd595..abeeafd 100644
--- a/3b_sim/ccpu.cpp
+++ b/3b_sim/ccpu.cpp
@@ -127,8 +127,10 @@ void CCpu::updateFlags(CDatd val, CDat a, CDat b) {
 	this->m_Z = (val == 0);
 	this->m_S = ((val >> (BIT_LEN-1)) & 0x1);
 	this->m_C = ((val >> (BIT_LEN)) & 0x1);
-	bool v = (((a ^ b) >> (BIT_LEN-1)) & 0x1) ? true : false;
-	this->m_O = (this->m_S != v);
+	bool a_31 = ((a >> (BIT_LEN-1)) & 0x1);
+	bool b_31 = ((b >> (BIT_LEN-1)) & 0x1);
+	bool val_31 = ((val >> (BIT_LEN-1)) & 0x1);
+	this->m_O = ((a_31 && b_31 && !val_31) || (!a_31 && !b_31 && val_31));
 }
 
 void CCpu::updateCarry(bool c)
diff --git a/3c_disasm/instr/cmp.cpp b/3c_disasm/instr/cmp.cpp
index 7924ed7..b9b02bf 100644
--- a/3c_disasm/instr/cmp.cpp
+++ b/3c_disasm/instr/cmp.cpp
@@ -56,7 +56,7 @@ void Ccmp::execInstr()
 	CDat ra = this->m_cpu->getRegister(m_ra);
 	CDat rb = this->m_cpu->getRegister(m_rb);
 	CDatd val = ra - rb;
-	this->m_cpu->updateFlags(val, ra, rb);
+	this->m_cpu->updateFlags(val, ra, (~rb)+1);
 }
 
 std::string Ccmp::toString()
diff --git a/3c_disasm/instr/cmpi.cpp b/3c_disasm/instr/cmpi.cpp
index 0de9659..2a80bf7 100644
--- a/3c_disasm/instr/cmpi.cpp
+++ b/3c_disasm/instr/cmpi.cpp
@@ -41,6 +41,7 @@ Ccmpi::Ccmpi()
 	name = "cmpi";
 }
 
+
 void Ccmpi::evalInstr()
 {
 	argbits >>= 3;
@@ -57,7 +58,7 @@ void Ccmpi::execInstr()
 	//cout << "should exec " << this->toString() << endl;
 	CDat ra = this->m_cpu->getRegister(m_ra);
 	CDatd reg = ra - this->m_imm;
-	this->m_cpu->updateFlags(reg, ra, this->m_imm);
+	this->m_cpu->updateFlags(reg, ra, (~this->m_imm)+1);
 }
 
 std::string Ccmpi::toString()
@@ -69,7 +70,7 @@ std::string Ccmpi::toString()
 	if(m_s) op << 'S';
 	if(m_c) op << 'C';
 
-	op << this->getConditionFlag() << " r" << m_rd << ", r" << m_ra << ", " << m_imm;
+	op << this->getConditionFlag() << " r" << m_ra << ", " << m_imm;
 
 	return op.str();
 }
diff --git a/3c_disasm/instr/sub.cpp b/3c_disasm/instr/sub.cpp
index d174735..6936f52 100644
--- a/3c_disasm/instr/sub.cpp
+++ b/3c_disasm/instr/sub.cpp
@@ -64,7 +64,7 @@ void Csub::execInstr()
 	CDatd val = ra - rb;
 	this->m_cpu->setRegister(m_rd, val);
 	if(!this->m_d) {
-		this->m_cpu->updateFlags(val, ra, rb);
+		this->m_cpu->updateFlags(val, ra, (~rb)+1);
 	}
 }
 
diff --git a/3c_disasm/instr/subi.cpp b/3c_disasm/instr/subi.cpp
index 701599c..d264ee3 100644
--- a/3c_disasm/instr/subi.cpp
+++ b/3c_disasm/instr/subi.cpp
@@ -66,7 +66,7 @@ void Csubi::execInstr()
 	CDatd reg = ra - this->m_imm;
 	this->m_cpu->setRegister(m_rd, reg);
 	if(!this->m_d) {
-		this->m_cpu->updateFlags(reg, ra, this->m_imm);
+		this->m_cpu->updateFlags(reg, ra, (~this->m_imm)+1);
 	}
 }
 
-- 
2.25.1