ui: Refactor DisplayIdentification to use ftl::stable_hash
Replace cityHash64Len0To16 with ftl::stable_hash which can handle up to
64 bytes string instead of just up to 16.
Bug: 185536303
Bug: 194863377
Test: DisplayIdentification_test
Change-Id: I90056145033ed5798dd5f5d99884028749d5d879
diff --git a/libs/ui/DisplayIdentification.cpp b/libs/ui/DisplayIdentification.cpp
index 82e5427..0908ae8 100644
--- a/libs/ui/DisplayIdentification.cpp
+++ b/libs/ui/DisplayIdentification.cpp
@@ -23,67 +23,13 @@
#include <optional>
#include <span>
+#include <ftl/hash.h>
#include <log/log.h>
-
#include <ui/DisplayIdentification.h>
namespace android {
namespace {
-template <class T>
-inline T load(const void* p) {
- static_assert(std::is_integral<T>::value, "T must be integral");
-
- T r;
- std::memcpy(&r, p, sizeof(r));
- return r;
-}
-
-uint64_t rotateByAtLeast1(uint64_t val, uint8_t shift) {
- return (val >> shift) | (val << (64 - shift));
-}
-
-uint64_t shiftMix(uint64_t val) {
- return val ^ (val >> 47);
-}
-
-__attribute__((no_sanitize("unsigned-integer-overflow")))
-uint64_t hash64Len16(uint64_t u, uint64_t v) {
- constexpr uint64_t kMul = 0x9ddfea08eb382d69;
- uint64_t a = (u ^ v) * kMul;
- a ^= (a >> 47);
- uint64_t b = (v ^ a) * kMul;
- b ^= (b >> 47);
- b *= kMul;
- return b;
-}
-
-__attribute__((no_sanitize("unsigned-integer-overflow")))
-uint64_t hash64Len0To16(const char* s, uint64_t len) {
- constexpr uint64_t k2 = 0x9ae16a3b2f90404f;
- constexpr uint64_t k3 = 0xc949d7c7509e6557;
-
- if (len > 8) {
- const uint64_t a = load<uint64_t>(s);
- const uint64_t b = load<uint64_t>(s + len - 8);
- return hash64Len16(a, rotateByAtLeast1(b + len, static_cast<uint8_t>(len))) ^ b;
- }
- if (len >= 4) {
- const uint32_t a = load<uint32_t>(s);
- const uint32_t b = load<uint32_t>(s + len - 4);
- return hash64Len16(len + (a << 3), b);
- }
- if (len > 0) {
- const unsigned char a = static_cast<unsigned char>(s[0]);
- const unsigned char b = static_cast<unsigned char>(s[len >> 1]);
- const unsigned char c = static_cast<unsigned char>(s[len - 1]);
- const uint32_t y = static_cast<uint32_t>(a) + (static_cast<uint32_t>(b) << 8);
- const uint32_t z = static_cast<uint32_t>(len) + (static_cast<uint32_t>(c) << 2);
- return shiftMix(y * k2 ^ z * k3) * k2;
- }
- return k2;
-}
-
using byte_view = std::span<const uint8_t>;
constexpr size_t kEdidBlockSize = 128;
@@ -320,7 +266,7 @@
// Hash model string instead of using product code or (integer) serial number, since the latter
// have been observed to change on some displays with multiple inputs. Use a stable hash instead
// of std::hash which is only required to be same within a single execution of a program.
- const uint32_t modelHash = static_cast<uint32_t>(cityHash64Len0To16(modelString));
+ const uint32_t modelHash = static_cast<uint32_t>(*ftl::stable_hash(modelString));
// Parse extension blocks.
std::optional<Cea861ExtensionBlock> cea861Block;
@@ -394,13 +340,4 @@
return PhysicalDisplayId::fromEdid(0, kVirtualEdidManufacturerId, id);
}
-uint64_t cityHash64Len0To16(std::string_view sv) {
- auto len = sv.length();
- if (len > 16) {
- ALOGE("%s called with length %zu. Only hashing the first 16 chars", __FUNCTION__, len);
- len = 16;
- }
- return hash64Len0To16(sv.data(), len);
-}
-
} // namespace android
diff --git a/libs/ui/include/ui/DisplayIdentification.h b/libs/ui/include/ui/DisplayIdentification.h
index fc9c0f4..8bc2017 100644
--- a/libs/ui/include/ui/DisplayIdentification.h
+++ b/libs/ui/include/ui/DisplayIdentification.h
@@ -80,7 +80,4 @@
PhysicalDisplayId getVirtualDisplayId(uint32_t id);
-// CityHash64 implementation that only hashes at most the first 16 characters of the given string.
-uint64_t cityHash64Len0To16(std::string_view sv);
-
} // namespace android
diff --git a/libs/ui/tests/DisplayIdentification_test.cpp b/libs/ui/tests/DisplayIdentification_test.cpp
index 736979a..721b466 100644
--- a/libs/ui/tests/DisplayIdentification_test.cpp
+++ b/libs/ui/tests/DisplayIdentification_test.cpp
@@ -21,9 +21,9 @@
#include <functional>
#include <string_view>
+#include <ftl/hash.h>
#include <gmock/gmock.h>
#include <gtest/gtest.h>
-
#include <ui/DisplayIdentification.h>
using ::testing::ElementsAre;
@@ -135,7 +135,7 @@
}
uint32_t hash(const char* str) {
- return static_cast<uint32_t>(cityHash64Len0To16(str));
+ return static_cast<uint32_t>(*ftl::stable_hash(str));
}
} // namespace
@@ -188,6 +188,7 @@
EXPECT_STREQ("SEC", edid->pnpId.data());
// ASCII text should be used as fallback if display name and serial number are missing.
EXPECT_EQ(hash("121AT11-801"), edid->modelHash);
+ EXPECT_EQ(hash("121AT11-801"), 626564263);
EXPECT_TRUE(edid->displayName.empty());
EXPECT_EQ(12610, edid->productId);
EXPECT_EQ(21, edid->manufactureOrModelYear);
@@ -199,6 +200,7 @@
EXPECT_EQ(0x22f0u, edid->manufacturerId);
EXPECT_STREQ("HWP", edid->pnpId.data());
EXPECT_EQ(hash("HP ZR30w"), edid->modelHash);
+ EXPECT_EQ(hash("HP ZR30w"), 918492362);
EXPECT_EQ("HP ZR30w", edid->displayName);
EXPECT_EQ(10348, edid->productId);
EXPECT_EQ(22, edid->manufactureOrModelYear);
@@ -210,6 +212,7 @@
EXPECT_EQ(0x4c2du, edid->manufacturerId);
EXPECT_STREQ("SAM", edid->pnpId.data());
EXPECT_EQ(hash("SAMSUNG"), edid->modelHash);
+ EXPECT_EQ(hash("SAMSUNG"), 1201368132);
EXPECT_EQ("SAMSUNG", edid->displayName);
EXPECT_EQ(2302, edid->productId);
EXPECT_EQ(21, edid->manufactureOrModelYear);
@@ -227,6 +230,7 @@
EXPECT_EQ(13481, edid->manufacturerId);
EXPECT_STREQ("MEI", edid->pnpId.data());
EXPECT_EQ(hash("Panasonic-TV"), edid->modelHash);
+ EXPECT_EQ(hash("Panasonic-TV"), 3876373262);
EXPECT_EQ("Panasonic-TV", edid->displayName);
EXPECT_EQ(41622, edid->productId);
EXPECT_EQ(29, edid->manufactureOrModelYear);
@@ -244,6 +248,7 @@
EXPECT_EQ(8355, edid->manufacturerId);
EXPECT_STREQ("HEC", edid->pnpId.data());
EXPECT_EQ(hash("Hisense"), edid->modelHash);
+ EXPECT_EQ(hash("Hisense"), 2859844809);
EXPECT_EQ("Hisense", edid->displayName);
EXPECT_EQ(0, edid->productId);
EXPECT_EQ(29, edid->manufactureOrModelYear);
@@ -261,6 +266,7 @@
EXPECT_EQ(3724, edid->manufacturerId);
EXPECT_STREQ("CTL", edid->pnpId.data());
EXPECT_EQ(hash("LP2361"), edid->modelHash);
+ EXPECT_EQ(hash("LP2361"), 1523181158);
EXPECT_EQ("LP2361", edid->displayName);
EXPECT_EQ(9373, edid->productId);
EXPECT_EQ(23, edid->manufactureOrModelYear);
@@ -281,6 +287,7 @@
// Serial number should be used as fallback if display name is invalid.
const auto modelHash = hash("CN4202137Q");
EXPECT_EQ(modelHash, edid->modelHash);
+ EXPECT_EQ(modelHash, 3582951527);
EXPECT_TRUE(edid->displayName.empty());
// Parsing should succeed even if EDID is truncated.