From 0d51df17795897bf151ce75484fcd39ebcac34fc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=91=D1=80=D0=B0=D0=BD=D0=B8=D0=BC=D0=B8=D1=80=20=D0=9A?=
 =?UTF-8?q?=D0=B0=D1=80=D0=B0=D1=9F=D0=B8=D1=9B?=
 <branimirkaradzic@gmail.com>
Date: Wed, 19 Apr 2023 19:01:00 -0700
Subject: [PATCH] Fixed rsqrt, and sqrt. Added more tests.

---
 include/bx/inline/math.inl | 53 ++++++++++++++++--------------------
 tests/math_test.cpp        | 56 ++++++++++++++++++++++++++++++++++++--
 2 files changed, 77 insertions(+), 32 deletions(-)

diff --git a/include/bx/inline/math.inl b/include/bx/inline/math.inl
index f73a548..19fb03d 100644
--- a/include/bx/inline/math.inl
+++ b/include/bx/inline/math.inl
@@ -212,17 +212,27 @@ namespace bx
 
 	inline BX_CONST_FUNC float rsqrtRef(float _a)
 	{
+		if (_a < kNearZero)
+		{
+			return kInfinity;
+		}
+
 		return pow(_a, -0.5f);
 	}
 
 	inline BX_CONST_FUNC float sqrtRef(float _a)
 	{
-		if (_a < kNearZero)
-		{
-			return 0.0f;
-		}
+		return _a*pow(_a, -0.5f);
+	}
 
-		return 1.0f/rsqrtRef(_a);
+	inline BX_CONST_FUNC float rsqrtSimd(float _a)
+	{
+		const simd128_t aa     = simd_splat(_a);
+		const simd128_t rsqrta = simd_rsqrt_nr(aa);
+		float result;
+		simd_stx(&result, rsqrta);
+
+		return result;
 	}
 
 	inline BX_CONST_FUNC float sqrtSimd(float _a)
@@ -235,30 +245,6 @@ namespace bx
 		return result;
 	}
 
-	inline BX_CONST_FUNC float sqrt(float _a)
-	{
-#if BX_CONFIG_SUPPORTS_SIMD
-		return sqrtSimd(_a);
-#else
-		return sqrtRef(_a);
-#endif // BX_CONFIG_SUPPORTS_SIMD
-	}
-
-	inline BX_CONST_FUNC float rsqrtSimd(float _a)
-	{
-		if (_a < kNearZero)
-		{
-			return 0.0f;
-		}
-
-		const simd128_t aa     = simd_splat(_a);
-		const simd128_t rsqrta = simd_rsqrt_nr(aa);
-		float result;
-		simd_stx(&result, rsqrta);
-
-		return result;
-	}
-
 	inline BX_CONST_FUNC float rsqrt(float _a)
 	{
 #if BX_CONFIG_SUPPORTS_SIMD
@@ -268,6 +254,15 @@ namespace bx
 #endif // BX_CONFIG_SUPPORTS_SIMD
 	}
 
+	inline BX_CONST_FUNC float sqrt(float _a)
+	{
+#if BX_CONFIG_SUPPORTS_SIMD
+		return sqrtSimd(_a);
+#else
+		return sqrtRef(_a);
+#endif // BX_CONFIG_SUPPORTS_SIMD
+	}
+
 	inline BX_CONSTEXPR_FUNC float trunc(float _a)
 	{
 		return float(int(_a) );
diff --git a/tests/math_test.cpp b/tests/math_test.cpp
index 7a1de3f..702dbd1 100644
--- a/tests/math_test.cpp
+++ b/tests/math_test.cpp
@@ -106,16 +106,42 @@ TEST_CASE("libm", "")
 		REQUIRE(bx::isEqual(bx::exp(xx), ::expf(xx), 0.00001f) );
 	}
 
-	for (float xx = 0.0f; xx < 100.0f; xx += 0.1f)
+	// rsqrt
+	REQUIRE(bx::isInfinite(1.0f/::sqrtf(0.0f) ) );
+	REQUIRE(bx::isInfinite(bx::rsqrt(0.0f) ) );
+
+	for (float xx = bx::kNearZero; xx < 100.0f; xx += 0.1f)
 	{
 		bx::write(writer, &err, "rsqrt(%f) == %f (expected: %f)\n", xx, bx::rsqrt(xx), 1.0f/::sqrtf(xx) );
 		REQUIRE(err.isOk() );
 		REQUIRE(bx::isEqual(bx::rsqrt(xx), 1.0f/::sqrtf(xx), 0.00001f) );
 	}
 
+	// rsqrtRef
+	REQUIRE(bx::isInfinite(bx::rsqrtRef(0.0f) ) );
+
+	for (float xx = bx::kNearZero; xx < 100.0f; xx += 0.1f)
+	{
+		bx::write(writer, &err, "rsqrtRef(%f) == %f (expected: %f)\n", xx, bx::rsqrtRef(xx), 1.0f/::sqrtf(xx) );
+		REQUIRE(err.isOk() );
+		REQUIRE(bx::isEqual(bx::rsqrtRef(xx), 1.0f/::sqrtf(xx), 0.00001f) );
+	}
+
+	// rsqrtSimd
+	REQUIRE(bx::isInfinite(bx::rsqrtSimd(0.0f) ) );
+
+	for (float xx = bx::kNearZero; xx < 100.0f; xx += 0.1f)
+	{
+		bx::write(writer, &err, "rsqrtSimd(%f) == %f (expected: %f)\n", xx, bx::rsqrtSimd(xx), 1.0f/::sqrtf(xx) );
+		REQUIRE(err.isOk() );
+		REQUIRE(bx::isEqual(bx::rsqrtSimd(xx), 1.0f/::sqrtf(xx), 0.00001f) );
+	}
+
+	// sqrt
+	REQUIRE(bx::isNan(::sqrtf(-1.0f) ) );
 	REQUIRE(bx::isNan(bx::sqrt(-1.0f) ) );
-	REQUIRE(bx::isEqual(bx::sqrt(0.0f), 0.0f, 0.0f) );
-	REQUIRE(bx::isEqual(bx::sqrt(1.0f), 1.0f, 0.0f) );
+	REQUIRE(bx::isEqual(bx::sqrt(0.0f), ::sqrtf(0.0f), 0.0f) );
+	REQUIRE(bx::isEqual(bx::sqrt(1.0f), ::sqrtf(1.0f), 0.0f) );
 
 	for (float xx = 0.0f; xx < 1000000.0f; xx += 1000.f)
 	{
@@ -124,6 +150,30 @@ TEST_CASE("libm", "")
 		REQUIRE(bx::isEqual(bx::sqrt(xx), ::sqrtf(xx), 0.00001f) );
 	}
 
+	// sqrtRef
+	REQUIRE(bx::isNan(bx::sqrtRef(-1.0f) ) );
+	REQUIRE(bx::isEqual(bx::sqrtRef(0.0f), ::sqrtf(0.0f), 0.0f) );
+	REQUIRE(bx::isEqual(bx::sqrtRef(1.0f), ::sqrtf(1.0f), 0.0f) );
+
+	for (float xx = 0.0f; xx < 1000000.0f; xx += 1000.f)
+	{
+		bx::write(writer, &err, "sqrtRef(%f) == %f (expected: %f)\n", xx, bx::sqrtRef(xx), ::sqrtf(xx) );
+		REQUIRE(err.isOk() );
+		REQUIRE(bx::isEqual(bx::sqrtRef(xx), ::sqrtf(xx), 0.00001f) );
+	}
+
+	// sqrtSimd
+	REQUIRE(bx::isNan(bx::sqrtSimd(-1.0f) ) );
+	REQUIRE(bx::isEqual(bx::sqrtSimd(0.0f), ::sqrtf(0.0f), 0.0f) );
+	REQUIRE(bx::isEqual(bx::sqrtSimd(1.0f), ::sqrtf(1.0f), 0.0f) );
+
+	for (float xx = 0.0f; xx < 1000000.0f; xx += 1000.f)
+	{
+		bx::write(writer, &err, "sqrtSimd(%f) == %f (expected: %f)\n", xx, bx::sqrtSimd(xx), ::sqrtf(xx) );
+		REQUIRE(err.isOk() );
+		REQUIRE(bx::isEqual(bx::sqrtSimd(xx), ::sqrtf(xx), 0.00001f) );
+	}
+
 	for (float xx = 0.0f; xx < 100.0f; xx += 0.1f)
 	{
 		bx::write(writer, &err, "sqrt(%f) == %f (expected: %f)\n", xx, bx::sqrt(xx), ::sqrtf(xx) );