From 9b872ce0b2c2f25e86ee9040daddfc19d8c308fc Mon Sep 17 00:00:00 2001
From: Guillaume Chatelet <gchatelet@google.com>
Date: Tue, 13 Mar 2018 10:58:42 +0100
Subject: [PATCH] Add cx16 (cmpxchg16b) cpuid flag. Fixes #30

---
 include/cpuinfo_x86.h | 2 ++
 src/cpuinfo_x86.c     | 5 +++++
 2 files changed, 7 insertions(+)

diff --git a/include/cpuinfo_x86.h b/include/cpuinfo_x86.h
index ff30182..0123ddb 100644
--- a/include/cpuinfo_x86.h
+++ b/include/cpuinfo_x86.h
@@ -54,6 +54,7 @@ typedef struct {
 
   int smx : 1;
   int sgx : 1;
+  int cx16 : 1;  // aka. CMPXCHG16B
 
   // Make sure to update X86FeaturesEnum below if you add a field here.
 } X86Features;
@@ -138,6 +139,7 @@ typedef enum {
   X86_AVX512_4VBMI2,
   X86_SMX,
   X86_SGX,
+  X86_CX16,
   X86_LAST_,
 } X86FeaturesEnum;
 
diff --git a/src/cpuinfo_x86.c b/src/cpuinfo_x86.c
index 05258f7..390e8c9 100644
--- a/src/cpuinfo_x86.c
+++ b/src/cpuinfo_x86.c
@@ -96,6 +96,7 @@ static void ParseCpuId(const uint32_t max_cpuid_leaf, X86Info* info) {
   info->stepping = ExtractBitRange(leaf_1.eax, 3, 0);
 
   features->smx = IsBitSet(leaf_1.ecx, 6);
+  features->cx16 = IsBitSet(leaf_1.ecx, 13);
   features->aes = IsBitSet(leaf_1.ecx, 25);
   features->f16c = IsBitSet(leaf_1.ecx, 29);
   features->sgx = IsBitSet(leaf_7.ebx, 2);
@@ -319,6 +320,8 @@ int GetX86FeaturesEnumValue(const X86Features* features,
       return features->smx;
     case X86_SGX:
       return features->sgx;
+    case X86_CX16:
+      return features->cx16;
     case X86_LAST_:
       break;
   }
@@ -385,6 +388,8 @@ const char* GetX86FeaturesEnumName(X86FeaturesEnum value) {
       return "smx";
     case X86_SGX:
       return "sgx";
+    case X86_CX16:
+      return "cx16";
     case X86_LAST_:
       break;
   }