libmath: Add HashCombine
Add a helper function to combine hashes and
make half and mat/vec std::hashable.
Bug: 158790260
Test: libmath unit tests
Change-Id: I11eb70152ce5a35a6d833cd108732e5b21704fe1
diff --git a/libs/math/Android.bp b/libs/math/Android.bp
index 22d4712..ab96950 100644
--- a/libs/math/Android.bp
+++ b/libs/math/Android.bp
@@ -22,6 +22,7 @@
"com.android.media.swcodec",
"com.android.neuralnetworks",
],
+
min_sdk_version: "29",
export_include_dirs: ["include"],
@@ -32,4 +33,23 @@
}
}
+cc_library_headers {
+ name: "libmath_headers",
+ export_include_dirs: ["include"],
+ host_supported: true,
+ vendor_available: true,
+
+ apex_available: [
+ "//apex_available:anyapex",
+ "//apex_available:platform",
+ ],
+ min_sdk_version: "apex_inherit",
+
+ target: {
+ windows: {
+ enabled: true,
+ }
+ }
+}
+
subdirs = ["tests"]
diff --git a/libs/math/include/math/HashCombine.h b/libs/math/include/math/HashCombine.h
new file mode 100644
index 0000000..e91b52b
--- /dev/null
+++ b/libs/math/include/math/HashCombine.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <functional>
+
+namespace android {
+static inline void hashCombineSingleHashed(size_t& combinedHash, size_t hash) {
+ combinedHash = 31 * combinedHash + hash;
+}
+
+template<typename T>
+static inline void hashCombineSingle(size_t& combinedHash, const T& val) {
+ hashCombineSingleHashed(combinedHash, std::hash<T>{}(val));
+}
+
+template<typename... Types>
+static inline size_t hashCombine(const Types& ... args) {
+ size_t hash = 0;
+ ( hashCombineSingle(hash, args), ... );
+ return hash;
+}
+
+} // namespace android
\ No newline at end of file
diff --git a/libs/math/include/math/TVecHelpers.h b/libs/math/include/math/TVecHelpers.h
index 20f852f..0dac662 100644
--- a/libs/math/include/math/TVecHelpers.h
+++ b/libs/math/include/math/TVecHelpers.h
@@ -19,9 +19,11 @@
#include <math.h>
#include <stdint.h>
+#include <math/HashCombine.h>
#include <sys/types.h>
#include <cmath>
+#include <functional>
#include <limits>
#include <iostream>
@@ -250,6 +252,17 @@
}
return r;
}
+
+ // This isn't strictly a unary operator, but it is a common place shared between both
+ // matrix and vector classes
+ size_t hash() const {
+ VECTOR<T> const& rv(static_cast<VECTOR<T> const&>(*this));
+ size_t hashed = 0;
+ for (size_t i = 0; i < rv.size(); i++) {
+ android::hashCombineSingle(hashed, rv[i]);
+ }
+ return hashed;
+ }
};
/*
@@ -606,3 +619,16 @@
// -------------------------------------------------------------------------------------
} // namespace details
} // namespace android
+
+namespace std {
+ template<template<typename T> class VECTOR, typename T>
+ struct hash<VECTOR<T>> {
+ static constexpr bool IS_VECTOR =
+ std::is_base_of<android::details::TVecUnaryOperators<VECTOR, T>, VECTOR<T>>::value;
+
+ typename std::enable_if<IS_VECTOR, size_t>::type
+ operator()(const VECTOR<T>& v) const {
+ return v.hash();
+ }
+ };
+}
diff --git a/libs/math/include/math/half.h b/libs/math/include/math/half.h
index 617a0ab..5ec9bf7 100644
--- a/libs/math/include/math/half.h
+++ b/libs/math/include/math/half.h
@@ -17,6 +17,7 @@
#pragma once
#include <stdint.h>
+#include <functional>
#include <iosfwd>
#include <limits>
#include <type_traits>
@@ -202,6 +203,12 @@
inline static constexpr type signaling_NaN() noexcept { return android::half(android::half::binary, 0x7dff); }
};
+template<> struct hash<android::half> {
+ size_t operator()(const android::half& half) {
+ return std::hash<float>{}(half);
+ }
+};
+
} // namespace std
#ifdef LIKELY_DEFINED_LOCAL
diff --git a/libs/math/tests/Android.bp b/libs/math/tests/Android.bp
index 0184f56..472d337 100644
--- a/libs/math/tests/Android.bp
+++ b/libs/math/tests/Android.bp
@@ -41,3 +41,10 @@
static_libs: ["libmath"],
cflags: ["-Wall", "-Werror"],
}
+
+cc_test {
+ name: "hashcombine_test",
+ srcs: ["hashcombine_test.cpp"],
+ static_libs: ["libmath"],
+ cflags: ["-Wall", "-Werror"],
+}
diff --git a/libs/math/tests/half_test.cpp b/libs/math/tests/half_test.cpp
index 604072e..a514d98 100644
--- a/libs/math/tests/half_test.cpp
+++ b/libs/math/tests/half_test.cpp
@@ -94,4 +94,13 @@
EXPECT_EQ(f4.xy, h2);
}
+
+TEST_F(HalfTest, Hash) {
+ float4 f4a(1,2,3,4);
+ float4 f4b(2,2,3,4);
+ half4 h4a(f4a), h4b(f4b);
+
+ EXPECT_NE(std::hash<half4>{}(h4a), std::hash<half4>{}(h4b));
+}
+
}; // namespace android
diff --git a/libs/math/tests/hashcombine_test.cpp b/libs/math/tests/hashcombine_test.cpp
new file mode 100644
index 0000000..96c6e81
--- /dev/null
+++ b/libs/math/tests/hashcombine_test.cpp
@@ -0,0 +1,43 @@
+/*
+ * Copyright 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "HashCombineTest"
+
+#include <math.h>
+#include <stdlib.h>
+
+#include <math/half.h>
+#include <math/vec4.h>
+
+#include <gtest/gtest.h>
+
+namespace android {
+
+class HashCombineTest : public testing::Test {
+protected:
+};
+
+TEST_F(HashCombineTest, Basics) {
+ char a = 40;
+ int b = 32;
+ int c = 55;
+ float d = 42.f;
+ float d_ = 42.1f;
+
+ EXPECT_NE(hashCombine(a, b, c, d), hashCombine(a, b, c, d_));
+}
+
+}; // namespace android