From a490e2cf1ef7257b40bcb45df6bde5972df2ac13 Mon Sep 17 00:00:00 2001
From: Victor Chang <vichang@google.com>
Date: Fri, 27 Dec 2024 14:04:08 +0000
Subject: Extract implementation of script and locale matching into
 LocaleDataLookup.h

It helps adding new unit tests, and fixing correctness and performance
bugs later.

Bug: 386340812
Test: atest libandroidfw_tests
Change-Id: I4d3ee1333637d2cd22d5fdfad730935951feeccb
---
 .../androidfw/include/androidfw/LocaleDataLookup.h | 79 ++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 libs/androidfw/include/androidfw/LocaleDataLookup.h

(limited to 'libs/androidfw/include')

diff --git a/libs/androidfw/include/androidfw/LocaleDataLookup.h b/libs/androidfw/include/androidfw/LocaleDataLookup.h
new file mode 100644
index 000000000000..7fde7123ed0b
--- /dev/null
+++ b/libs/androidfw/include/androidfw/LocaleDataLookup.h
@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2024 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 <stddef.h>
+#include <stdint.h>
+
+
+namespace android {
+
+namespace hidden {
+    bool isRepresentative(uint64_t packed_locale);
+}
+
+constexpr size_t SCRIPT_LENGTH = 4;
+
+constexpr inline uint32_t packLocale(const char* language, const char* region) {
+    const unsigned char* lang = reinterpret_cast<const unsigned char*>(language);
+    const unsigned char* reg = reinterpret_cast<const unsigned char*>(region);
+    return (static_cast<uint32_t>(lang[0]) << 24u) |
+            (static_cast<uint32_t>(lang[1]) << 16u) |
+            (static_cast<uint32_t>(reg[0]) << 8u) |
+            static_cast<uint32_t>(reg[1]);
+}
+
+constexpr inline uint32_t dropRegion(uint32_t packed_locale) {
+    return packed_locale & 0xFFFF0000LU;
+}
+
+constexpr inline bool hasRegion(uint32_t packed_locale) {
+    return (packed_locale & 0x0000FFFFLU) != 0;
+}
+
+/**
+ * Return nullptr if the key isn't found. The input packed_lang_region can be computed
+ * by android::packLocale.
+ * Note that the returned char* is either nullptr or 4-byte char seqeuence, but isn't
+ * a null-terminated string.
+ */
+const char* lookupLikelyScript(uint32_t packed_lang_region);
+/**
+ * Return false if the key isn't representative. The input lookup key can be computed
+ * by android::packLocale.
+ */
+bool inline isLocaleRepresentative(uint32_t language_and_region, const char* script) {
+    const unsigned char* s = reinterpret_cast<const unsigned char*>(script);
+    const uint64_t packed_locale = (
+            ((static_cast<uint64_t>(language_and_region)) << 32u) |
+            (static_cast<uint64_t>(s[0]) << 24u) |
+            (static_cast<uint64_t>(s[1]) << 16u) |
+            (static_cast<uint64_t>(s[2]) <<  8u) |
+            static_cast<uint64_t>(s[3]));
+
+    return hidden::isRepresentative(packed_locale);
+}
+
+/**
+ * Return a parent packed key for a given script and child packed key. Return 0 if
+ * no parent is found.
+ */
+uint32_t findParentLocalePackedKey(const char* script, uint32_t packed_lang_region);
+
+uint32_t getMaxAncestorTreeDepth();
+
+} // namespace android
-- 
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