Working on FPU

captainys · Sep 29, 2021 · 7dc815a · 7dc815a
1 parent 92e8a05
commit 7dc815a
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Showing 3 changed files with 33 additions and 4 deletions.
diff --git a/src/cpu/i486.h b/src/cpu/i486.h
@@ -362,6 +362,7 @@ class i486DX : public CPU
 		std::vector <std::string> GetStateText(void) const;
 
 		// Returns clocks passed.
+		unsigned int FCHS(i486DX &cpu);
 		unsigned int FLD1(i486DX &cpu);
 		unsigned int FLDL2T(i486DX &cpu);
 		unsigned int FLDZ(i486DX &cpu);

diff --git a/src/cpu/i486inst.cpp b/src/cpu/i486inst.cpp
@@ -1096,7 +1096,7 @@ void i486DX::FetchOperand(CPUCLASS &cpu,Instruction &inst,Operand &op1,Operand &
 		{
 			unsigned int MODR_M;
 			FUNCCLASS::PeekOperand8(cpu,MODR_M,inst,ptr,seg,offset,mem);
-			if(0xF0<=MODR_M && MODR_M<=0xFF)
+			if(0xE0==MODR_M || (0xF0<=MODR_M && MODR_M<=0xFF))
 			{
 				FUNCCLASS::FetchOperand8(cpu,inst,ptr,seg,offset,mem);
 			}
@@ -2169,6 +2169,17 @@ std::string i486DX::Instruction::Disassemble(const Operand &op1In,const Operand
 		{
 			disasm="?FPUINST"+cpputil::Ubtox(opCode)+" "+cpputil::Ubtox(operand[0]);
 		}
+		else if(0xC0<=operand[0] && operand[0]<=0xC7)
+		{
+			disasm="FLD ";
+			disasm+="ST(";
+			disasm.push_back('0'+operand[0]-0xC0);
+			disasm+=")";
+		}
+		else if(0xE0==operand[0])
+		{
+			disasm="FCHS";
+		}
 		else if(0xE8==operand[0])
 		{
 			disasm="FLD1";
@@ -5513,19 +5524,20 @@ unsigned int i486DX::RunOneInstruction(Memory &mem,InOut &io)
 		if(0xF0<=inst.operand[0] && inst.operand[0]<=0xFF)
 		{
 		}
+		else if(0xE0==inst.operand[0])
+		{
+			clocksPassed=state.fpuState.FCHS(*this);
+		}
 		else if(0xE8==inst.operand[0])
 		{
-			// FLD1
 			clocksPassed=state.fpuState.FLD1(*this);
 		}
 		else if(0xE9==inst.operand[0])
 		{
-			// FLDL2T
 			clocksPassed=state.fpuState.FLDL2T(*this);
 		}
 		else if(0xEE==inst.operand[0])
 		{
-			// FLDZ
 			clocksPassed=state.fpuState.FLDZ(*this);
 		}
 		else

diff --git a/src/cpu/i487.cpp b/src/cpu/i487.cpp
@@ -127,6 +127,22 @@ std::vector <std::string> i486DX::FPUState::GetStateText(void) const
 	return text;
 }
 
+unsigned int i486DX::FPUState::FCHS(i486DX &cpu)
+{
+	if(true==enabled)
+	{
+		if(0<stackPtr)
+		{
+			stack[stackPtr-1].value=-stack[stackPtr-1].value;
+			return 4;
+		}
+		else
+		{
+			// Raise NM exception.
+		}
+	}
+	return 0; // Let it abort.
+}
 unsigned int i486DX::FPUState::FLD1(i486DX &cpuState)
 {
 	if(true==enabled)