From e930ad8fa183310e0afb4a47df646e9cc9796c5a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Branimir=20Karad=C5=BEi=C4=87?= <branimirkaradzic@gmail.com>
Date: Wed, 30 May 2018 12:58:47 -0700
Subject: [PATCH] Added testpow2 test, and use improved version. Issue #184.

---
 include/bx/inline/uint32_t.inl | 10 ++++------
 tests/uint32_test.cpp          | 14 ++++++++++++++
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/include/bx/inline/uint32_t.inl b/include/bx/inline/uint32_t.inl
index 8b85bbe..a707521 100644
--- a/include/bx/inline/uint32_t.inl
+++ b/include/bx/inline/uint32_t.inl
@@ -453,12 +453,10 @@ namespace bx
 
 	inline uint32_t uint32_testpow2(uint32_t _a)
 	{
-		const uint32_t tmp0   = uint32_not(_a);
-		const uint32_t tmp1   = uint32_inc(tmp0);
-		const uint32_t tmp2   = uint32_and(_a, tmp1);
-		const uint32_t tmp3   = uint32_cmpeq(tmp2, _a);
-		const uint32_t tmp4   = uint32_cmpneq(_a, 0);
-		const uint32_t result = uint32_and(tmp3, tmp4);
+		const uint32_t tmp0   = uint32_dec(_a);
+		const uint32_t tmp1   = uint32_xor(_a, tmp0);
+		const uint32_t tmp2   = uint32_srl(tmp1, 1);
+		const uint32_t result = uint32_cmpeq(tmp2, tmp0);
 
 		return result;
 	}
diff --git a/tests/uint32_test.cpp b/tests/uint32_test.cpp
index ee0e53b..07c7213 100644
--- a/tests/uint32_test.cpp
+++ b/tests/uint32_test.cpp
@@ -69,3 +69,17 @@ TEST_CASE("halfTo/FromFloat", "")
 		REQUIRE(orig == hff);
 	}
 }
+
+TEST_CASE("uint32_testpow2", "")
+{
+	uint32_t shift = 0;
+
+	for (uint32_t ii = 0; ii < UINT32_MAX; ++ii)
+	{
+		if (bx::uint32_testpow2(ii) )
+		{
+			REQUIRE(ii == 1 << shift);
+			++shift;
+		}
+	}
+}