EMMS instruction shoots INT 6 (MMX instruction not supported in 486).

captainys · Feb 8, 2025 · 95e00d8 · 95e00d8
1 parent 758b548
commit 95e00d8
Show file tree

Hide file tree

Showing 3 changed files with 11 additions and 1 deletion.
diff --git a/src/cpu/i486inst.cpp b/src/cpu/i486inst.cpp
@@ -357,6 +357,7 @@ void i486DXCommon::MakeOpCodeRenumberTable(void)
 	opCodeRenumberTable[I486_OPCODE_XADD_RM8_R8]=I486_RENUMBER_XADD_RM8_R8;
 	opCodeRenumberTable[I486_OPCODE_XADD_RM_R]=I486_RENUMBER_XADD_RM_R;
 	opCodeRenumberTable[I486_OPCODE_CPUID]=I486_RENUMBER_CPUID;
+	opCodeRenumberTable[I486_OPCODE_EMMS]=I486_RENUMBER_EMMS;
 
 
 
@@ -464,7 +465,7 @@ void i486DXCommon::MakeOpCodeRenumberTable(void)
 	opCodeNeedOperandTable[I486_OPCODE_XCHG_EAX_EDI]=I486_NEEDOPERAND_NONE;
 	opCodeNeedOperandTable[I486_OPCODE_XLAT]=I486_NEEDOPERAND_NONE;
 	opCodeNeedOperandTable[I486_OPCODE_CPUID]=I486_NEEDOPERAND_NONE;
-
+	opCodeNeedOperandTable[I486_OPCODE_EMMS]=I486_NEEDOPERAND_NONE;
 
 	// RM_IMM8
 	opCodeNeedOperandTable[I486_OPCODE_C0_ROL_ROR_RCL_RCR_SAL_SAR_SHL_SHR_RM8_I8]=I486_NEEDOPERAND_RM_IMM8;
@@ -3384,6 +3385,10 @@ std::string i486DXCommon::Instruction::Disassemble(const Operand &op1In,const Op
 	case I486_OPCODE_CPUID:
 		disasm="CPUID";
 		break;
+
+	case I486_OPCODE_EMMS:
+		disasm="EMMS(INT 6)";
+		break;
 	}
 
 	if(INST_PREFIX_LOCK==instPrefix)

diff --git a/src/cpu/i486inst.h b/src/cpu/i486inst.h
@@ -559,6 +559,8 @@ enum
 	I486_OPCODE_XADD_RM_R=   0x0FC1,
 
 	I486_OPCODE_CPUID=       0x0FA2,
+
+	I486_OPCODE_EMMS=        0x0F77,  // EMMS.  Not supported.  Shoots INT 6
 };
 
 enum
@@ -1218,6 +1220,8 @@ enum
 
 	I486_RENUMBER_REALLY_UNDEFINED,
 
+	I486_RENUMBER_EMMS,  // EMMS.  Not supported.  Shoot INT 6
+
 I486_NUM_SUPPORTED_INSTRUCTIONS,
 };
 

diff --git a/src/cpu/i486runinstruction.h b/src/cpu/i486runinstruction.h
@@ -2167,6 +2167,7 @@ unsigned int i486DXFidelityLayer<FIDELITY>::RunOneInstruction(Memory &mem,InOut
 	{
 	case I486_RENUMBER_UNDEFINED_SHOOT_INT6:
 	case I486_RENUMBER_UNDEFINED_SHOOT_INT6_WIN31:
+	case I486_RENUMBER_EMMS: // 0x0F77 MMX instruction.  Used in the Win95 Media-Player Installer.
 		Interrupt(INT_INVALID_OPCODE,mem,0,0,false);
 		EIPIncrement=0;
 		clocksPassed=ClocksForHandlingException();