From 9e3a66d5bf58d01653b57189f86bcf68988a4786 Mon Sep 17 00:00:00 2001
From: Max Kellermann <mk@cm4all.com>
Date: Mon, 6 May 2024 23:04:41 +0200
Subject: [PATCH] util/djb_hash: make inline and constexpr
Allows calculating hashes at compile time.
---
src/util/djb_hash.cxx | 40 ----------------------------------------
src/util/djb_hash.hxx | 37 ++++++++++++++++++++++++++++++-------
src/util/meson.build | 1 -
3 files changed, 30 insertions(+), 48 deletions(-)
delete mode 100644 src/util/djb_hash.cxx
diff --git a/src/util/djb_hash.cxx b/src/util/djb_hash.cxx
deleted file mode 100644
index 559a692dd..000000000
--- a/src/util/djb_hash.cxx
+++ /dev/null
@@ -1,40 +0,0 @@
-// SPDX-License-Identifier: BSD-2-Clause
-// Copyright CM4all GmbH
-// author: Max Kellermann <mk@cm4all.com>
-
-#include "djb_hash.hxx"
-
-#include <cassert>
-
-[[gnu::always_inline]] [[gnu::hot]]
-static constexpr std::size_t
-djb_hash_update(std::size_t hash, std::byte b) noexcept
-{
- return (hash * 33) ^ static_cast<std::size_t>(b);
-}
-
-[[gnu::hot]]
-std::size_t
-djb_hash(std::span<const std::byte> src, std::size_t init) noexcept
-{
- std::size_t hash = init;
-
- for (const auto i : src)
- hash = djb_hash_update(hash, i);
-
- return hash;
-}
-
-[[gnu::hot]]
-std::size_t
-djb_hash_string(const char *p, std::size_t init) noexcept
-{
- assert(p != nullptr);
-
- std::size_t hash = init;
-
- while (*p != 0)
- hash = djb_hash_update(hash, static_cast<std::byte>(*p++));
-
- return hash;
-}
diff --git a/src/util/djb_hash.hxx b/src/util/djb_hash.hxx
index 6eff57013..bbf732a9f 100644
--- a/src/util/djb_hash.hxx
+++ b/src/util/djb_hash.hxx
@@ -14,12 +14,35 @@
static constexpr std::size_t DJB_HASH_INIT = 5381;
-[[gnu::pure]]
-std::size_t
-djb_hash(std::span<const std::byte> src,
- std::size_t init=DJB_HASH_INIT) noexcept;
+[[nodiscard]] [[gnu::always_inline]] [[gnu::hot]]
+constexpr std::size_t
+djb_hash_update(std::size_t hash, std::byte b) noexcept
+{
+ return (hash * 33) ^ static_cast<std::size_t>(b);
+}
-[[gnu::pure]]
-std::size_t
+[[nodiscard]] [[gnu::hot]]
+constexpr std::size_t
+djb_hash(std::span<const std::byte> src,
+ std::size_t init=DJB_HASH_INIT) noexcept
+{
+ std::size_t hash = init;
+
+ for (const auto i : src)
+ hash = djb_hash_update(hash, i);
+
+ return hash;
+}
+
+[[nodiscard]] [[gnu::hot]]
+constexpr std::size_t
djb_hash_string(const char *p,
- std::size_t init=DJB_HASH_INIT) noexcept;
+ std::size_t init=DJB_HASH_INIT) noexcept
+{
+ std::size_t hash = init;
+
+ while (*p != 0)
+ hash = djb_hash_update(hash, static_cast<std::byte>(*p++));
+
+ return hash;
+}
diff --git a/src/util/meson.build b/src/util/meson.build
index 4d69809d0..7ada1dd36 100644
--- a/src/util/meson.build
+++ b/src/util/meson.build
@@ -23,7 +23,6 @@ util = static_library(
'ByteReverse.cxx',
'format.c',
'BitReverse.cxx',
- 'djb_hash.cxx',
'Serial.cxx',
include_directories: inc,
)