FNCLEX

ergo720 · Feb 2, 2024 · bb9c5b1 · bb9c5b1
1 parent 333f171
commit bb9c5b1
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Showing 3 changed files with 18 additions and 0 deletions.
diff --git a/lib86cpu/core/emitter/x64/jit.cpp b/lib86cpu/core/emitter/x64/jit.cpp
@@ -5196,6 +5196,19 @@ lc86_jit::fldcw(decoded_instr *instr)
 	}
 }
 
+void
+lc86_jit::fnclex(decoded_instr *instr)
+{
+	if (m_cpu->cpu_ctx.hflags & (HFLG_CR0_EM | HFLG_CR0_TS)) {
+		RAISEin0_t(EXP_NM);
+	}
+	else {
+		LD_R16(AX, CPU_CTX_FSTATUS);
+		AND(AX, ~(FPU_FLG_SF | FPU_FLG_ES | FPU_FLG_BSY | FPU_EXP_ALL));
+		ST_R16(CPU_CTX_FSTATUS, AX);
+	}
+}
+
 void
 lc86_jit::fninit(decoded_instr *instr)
 {

diff --git a/lib86cpu/core/emitter/x64/jit.h b/lib86cpu/core/emitter/x64/jit.h
@@ -76,6 +76,7 @@ class lc86_jit : public Target {
 	void enter(decoded_instr *instr);
 	void fld(decoded_instr *instr);
 	void fldcw(decoded_instr *instr);
+	void fnclex(decoded_instr *instr);
 	void fninit(decoded_instr *instr);
 	void fnstcw(decoded_instr *instr);
 	void fnstsw(decoded_instr *instr);

diff --git a/lib86cpu/core/translate.cpp b/lib86cpu/core/translate.cpp
@@ -1158,6 +1158,10 @@ cpu_translate(cpu_t *cpu)
 			cpu->jit->fldcw(&instr);
 			break;
 
+		case ZYDIS_MNEMONIC_FNCLEX:
+			cpu->jit->fnclex(&instr);
+			break;
+
 		case ZYDIS_MNEMONIC_FNINIT:
 			cpu->jit->fninit(&instr);
 			break;