compat: rename hash's source file only

1 files changed, 146 insertions, 0 deletions

diff --git a/compat/hash.cpp b/compat/hash.cpp
new file mode 100644
index 00000000..3cb3cc35
--- /dev/null
+++ b/compat/hash.cpp
@@ -0,0 +1,146 @@
+#include "compat/defs.hpp"
+#include "hash.hpp"
+#include <Corrade/Containers/StringView.h>
+#include <bit>
+#include <utility>
+
+namespace floormat {
+
+namespace {
+
+using namespace floormat::Hash;
+
+[[maybe_unused]]
+CORRADE_ALWAYS_INLINE size_t fnvhash_uint_32(uint32_t x)
+{
+    constexpr auto params = fnvhash_params<sizeof(size_t)*8>{};
+    constexpr auto a = params.a, b = params.b;
+    auto hash = a;
+    const auto* str = (const char*)&x;
+
+    hash *= b; hash ^= (uint8_t)*str++; // 0
+    hash *= b; hash ^= (uint8_t)*str++; // 1
+    hash *= b; hash ^= (uint8_t)*str++; // 2
+    hash *= b; hash ^= (uint8_t)*str++; // 3
+
+    return hash;
+}
+
+CORRADE_ALWAYS_INLINE size_t fnvhash_uint_64(uint64_t x)
+{
+    constexpr auto params = fnvhash_params<sizeof(std::common_type_t<size_t>)*8>{};
+    constexpr auto a = params.a, b = params.b;
+    auto hash = a;
+    const auto* str = (const char*)&x;
+
+    hash *= b; hash ^= (uint8_t)*str++; // 0
+    hash *= b; hash ^= (uint8_t)*str++; // 1
+    hash *= b; hash ^= (uint8_t)*str++; // 2
+    hash *= b; hash ^= (uint8_t)*str++; // 3
+    hash *= b; hash ^= (uint8_t)*str++; // 4
+    hash *= b; hash ^= (uint8_t)*str++; // 5
+    hash *= b; hash ^= (uint8_t)*str++; // 6
+    hash *= b; hash ^= (uint8_t)*str++; // 7
+
+    return hash;
+}
+
+} // namespace
+
+uint32_t hash_32(const void* buf, size_t size) noexcept
+{
+    constexpr auto params = fnvhash_params<32>{};
+    constexpr auto a = params.a, b = params.b;
+    auto hash = a;
+    const auto *str = (const char*)buf, *const end = str + size;
+
+fm_UNROLL_4
+    for (; str != end; ++str)
+    {
+        hash *= b;
+        hash ^= (uint8_t)*str;
+    }
+    return hash;
+}
+
+uint64_t hash_64(const void* buf, size_t size) noexcept
+{
+    constexpr auto params = fnvhash_params<sizeof(size_t)*8>{};
+    constexpr auto a = params.a, b = params.b;
+    auto hash = a;
+    const auto *str = (const char*)buf, *const end = str + size;
+
+fm_UNROLL_8
+    for (; str != end; ++str)
+    {
+        hash *= b;
+        hash ^= (uint8_t)*str;
+    }
+    return hash;
+}
+
+size_t hash_buf(const void* buf, size_t size) noexcept
+{
+#if 1
+    if constexpr(sizeof nullptr > 4)
+        return hash_64(buf, size);
+    else
+#endif
+        return hash_32(buf, size);
+}
+
+size_t hash_int(uint32_t x) noexcept
+{
+#if 1
+    if constexpr(sizeof nullptr > 4)
+        return fnvhash_uint_64(x);
+    else
+#endif
+        return fnvhash_uint_32(x);
+}
+
+size_t hash_int(uint64_t x) noexcept
+{
+    return fnvhash_uint_64(x);
+}
+
+size_t hash_string_view::operator()(StringView s) const noexcept { return Hash::fnvhash_buf(s.data(), s.size()); }
+
+} // namespace floormat
+
+namespace floormat::Hash {
+
+size_t fnvhash_buf(const void* __restrict buf, size_t size, size_t seed) noexcept
+{
+    constexpr size_t b{fnvhash_params<sizeof nullptr*8>::b};
+    size_t full_rounds = size / 8, rest = size % 8;
+    size_t hash = seed;
+    const char* str = (const char*)buf;
+
+    while (full_rounds--)
+    {
+        hash *= b; hash ^= (uint8_t)*str++; // 0
+        hash *= b; hash ^= (uint8_t)*str++; // 1
+        hash *= b; hash ^= (uint8_t)*str++; // 2
+        hash *= b; hash ^= (uint8_t)*str++; // 3
+        hash *= b; hash ^= (uint8_t)*str++; // 4
+        hash *= b; hash ^= (uint8_t)*str++; // 5
+        hash *= b; hash ^= (uint8_t)*str++; // 6
+        hash *= b; hash ^= (uint8_t)*str++; // 7
+    }
+    switch (rest)
+    {
+    case 7: hash *= b; hash ^= (uint8_t)*str++; [[fallthrough]];
+    case 6: hash *= b; hash ^= (uint8_t)*str++; [[fallthrough]];
+    case 5: hash *= b; hash ^= (uint8_t)*str++; [[fallthrough]];
+    case 4: hash *= b; hash ^= (uint8_t)*str++; [[fallthrough]];
+    case 3: hash *= b; hash ^= (uint8_t)*str++; [[fallthrough]];
+    case 2: hash *= b; hash ^= (uint8_t)*str++; [[fallthrough]];
+    case 1: hash *= b; hash ^= (uint8_t)*str++; [[fallthrough]];
+    case 0: break;
+    default: std::unreachable();
+    }
+    return hash;
+}
+
+} // namespace floormat::Hash