From 3f8e93ad7a25f6129222a0a9cf79974e0bc95208 Mon Sep 17 00:00:00 2001
From: Patrick Pelissier <patrick.pelissier@gmail.com>
Date: Thu, 25 Jun 2020 23:45:39 +0200
Subject: [PATCH] Use of intrinsic for clz within MSVS

---
 m-core.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/m-core.h b/m-core.h
index 3243dc64..dd7a7570 100644
--- a/m-core.h
+++ b/m-core.h
@@ -1855,6 +1855,28 @@ static inline unsigned int m_core_clz64(uint64_t limb)
 {
   return M_UNLIKELY (limb == 0ULL) ? sizeof (uint64_t)*CHAR_BIT : (unsigned int) __builtin_clzll(limb) - (sizeof (unsigned long long) - sizeof (uint64_t)) * CHAR_BIT;
 }
+
+#elif defined(_MSC_VER)
+#include <intrin.h>
+static inline unsigned int m_core_clz32(uint32_t limb)
+{
+  unsigned long bit = 0;
+  if (_BitScanReverse( &bit_zero, limb ) != 0) {
+    return 31 - bit;
+  } else {
+    return 32;
+  }
+}
+static inline unsigned int m_core_clz64(uint64_t limb)
+{
+  unsigned long bit = 0;
+  if (_BitScanReverse64( &bit_zero, limb ) != 0) {
+    return 63 - bit;
+  } else {
+    return 64;
+  }
+}
+
 #else
 #define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