From 753060f232745ea2a3fa197a176c3a8675699053 Mon Sep 17 00:00:00 2001
From: assiduous <assiduous@diligentgraphics.com>
Date: Mon, 25 Jan 2021 14:41:17 -0800
Subject: Basic math: reworked ExtractBit and renamed to ExtractLSB; added
 tests

---
 Common/interface/BasicMath.hpp | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

(limited to 'Common/interface')

diff --git a/Common/interface/BasicMath.hpp b/Common/interface/BasicMath.hpp
index 78e9beaf..5f37c164 100644
--- a/Common/interface/BasicMath.hpp
+++ b/Common/interface/BasicMath.hpp
@@ -2189,18 +2189,24 @@ inline Uint32 BitInterleave16(Uint16 _x, Uint16 _y)
     return x | (y << 1u);
 }
 
+/// Returns the least-signficant bit and clears it in the input argument
 template <typename T>
-inline T ExtractBit(T& bits)
+typename std::enable_if<std::is_integral<T>::value, T>::type ExtractLSB(T& bits)
 {
-    static_assert(std::is_enum<T>::value || std::is_integral<T>::value, "T must be enum or integer type");
+    if (bits == T{0})
+        return 0;
 
-    using U = std::conditional_t<(sizeof(T) > sizeof(Uint32)), Uint64, Uint32>;
-    VERIFY_EXPR(static_cast<U>(bits) > 0);
+    const T bit = bits & ~(bits - T{1});
+    bits &= ~bit;
 
-    const U result = static_cast<U>(bits) & ~(static_cast<U>(bits) - U{1});
-    bits           = static_cast<T>(static_cast<U>(bits) & ~result);
+    return bit;
+}
 
-    return static_cast<T>(result);
+/// Returns the enum value representing the least-signficant bit and clears it in the input argument
+template <typename T>
+typename std::enable_if<std::is_enum<T>::value, T>::type ExtractLSB(T& bits)
+{
+    return static_cast<T>(ExtractLSB(reinterpret_cast<std::underlying_type<T>::type&>(bits)));
 }
 
 } // namespace Diligent
-- 
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