From 5da4668a0d928ffa527ca03642902c92c4b78a64 Mon Sep 17 00:00:00 2001
From: Merry <git@mary.rs>
Date: Sat, 23 Apr 2022 18:37:57 +0100
Subject: [PATCH] Squashed 'externals/mcl/' changes from a86a53843..761b7c05e

761b7c05e mcl: Build as PIC
4aad0b5e6 mcl/bit: Simplify sign_extend
0733afd2a mcl: Fix bug in non-template mcl::bit::ones
e26df0587 mcl: bit_field: Fix incorrect argument order in replicate_element

git-subtree-dir: externals/mcl
git-subtree-split: 761b7c05e80d789acf572b52175b852c6509e753
---
 CMakeLists.txt                |  2 +-
 include/mcl/bit/bit_field.hpp | 20 +++++++----------
 src/CMakeLists.txt            |  1 +
 tests/CMakeLists.txt          |  1 +
 tests/bit/bit_field_tests.cpp | 41 +++++++++++++++++++++++++++++++++++
 5 files changed, 52 insertions(+), 13 deletions(-)
 create mode 100644 tests/bit/bit_field_tests.cpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c1c28f61..3bf31637 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.12 FATAL_ERROR)
 include(GNUInstallDirs)
 
-project(mcl LANGUAGES CXX VERSION 0.1.3)
+project(mcl LANGUAGES CXX VERSION 0.1.7)
 
 # Project options
 option(MCL_WARNINGS_AS_ERRORS "Warnings as errors" ON)
diff --git a/include/mcl/bit/bit_field.hpp b/include/mcl/bit/bit_field.hpp
index e4fca8ef..b967ed4b 100644
--- a/include/mcl/bit/bit_field.hpp
+++ b/include/mcl/bit/bit_field.hpp
@@ -31,7 +31,7 @@ constexpr T ones(size_t count) {
     if (count == 0) {
         return 0;
     }
-    return ~static_cast<T>(0) >> (bitsizeof<T> - count);
+    return static_cast<T>(~static_cast<T>(0)) >> (bitsizeof<T> - count);
 }
 
 /// Create a mask of type T for bits [begin_bit, end_bit] inclusive.
@@ -143,11 +143,9 @@ template<size_t bit_count, BitIntegral T>
 constexpr T sign_extend(T value) {
     static_assert(bit_count != 0, "cannot sign-extend zero-sized value");
 
-    constexpr T m = ones<bit_count, T>();
-    if (get_bit<bit_count - 1, T>(value)) {
-        return value | ~m;
-    }
-    return value;
+    using S = std::make_signed_t<T>;
+    constexpr size_t shift_amount = bitsizeof<T> - bit_count;
+    return static_cast<T>(static_cast<S>(value << shift_amount) >> shift_amount);
 }
 
 /// Sign-extends a value that has bit_count bits to the full bitwidth of type T.
@@ -155,11 +153,9 @@ template<BitIntegral T>
 constexpr T sign_extend(size_t bit_count, T value) {
     ASSERT_MSG(bit_count != 0, "cannot sign-extend zero-sized value");
 
-    const T m = ones<T>(bit_count);
-    if (get_bit<T>(bit_count - 1, value)) {
-        return value | ~m;
-    }
-    return value;
+    using S = std::make_signed_t<T>;
+    const size_t shift_amount = bitsizeof<T> - bit_count;
+    return static_cast<T>(static_cast<S>(value << shift_amount) >> shift_amount);
 }
 
 /// Replicate an element across a value of type T.
@@ -192,7 +188,7 @@ constexpr T replicate_element(size_t element_size, T value) {
     if (element_size == bitsizeof<T>) {
         return value;
     }
-    return replicate_element<T>(static_cast<T>(value | (value << element_size)), element_size * 2);
+    return replicate_element<T>(element_size * 2, static_cast<T>(value | (value << element_size)));
 }
 
 template<BitIntegral T>
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index a25392b3..92d2d8e0 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -63,6 +63,7 @@ target_include_directories(mcl
 )
 target_compile_options(mcl PRIVATE ${MCL_CXX_FLAGS})
 target_link_libraries(mcl PUBLIC $<BUILD_INTERFACE:fmt::fmt>)
+set_property(TARGET mcl PROPERTY POSITION_INDEPENDENT_CODE ON)
 add_library(merry::mcl ALIAS mcl)
 
 include(CreateTargetDirectoryGroups)
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 1b60518d..1619f34c 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -1,4 +1,5 @@
 add_executable(mcl-tests
+    bit/bit_field_tests.cpp
     main.cpp
     mp/metavalue_tests.cpp
     mp/typelist_tests.cpp
diff --git a/tests/bit/bit_field_tests.cpp b/tests/bit/bit_field_tests.cpp
new file mode 100644
index 00000000..fba31eb5
--- /dev/null
+++ b/tests/bit/bit_field_tests.cpp
@@ -0,0 +1,41 @@
+// This file is part of the mcl project.
+// Copyright (c) 2022 merryhime
+// SPDX-License-Identifier: MIT
+
+#include <array>
+#include <tuple>
+
+#include <catch2/catch.hpp>
+#include <mcl/bit/bit_field.hpp>
+#include <mcl/stdint.hpp>
+
+TEST_CASE("mcl::bit::ones", "[bit]") {
+    const std::array cases{
+        std::make_tuple<size_t, u8>(0, 0x00),
+        std::make_tuple<size_t, u8>(1, 0x01),
+        std::make_tuple<size_t, u8>(2, 0x03),
+        std::make_tuple<size_t, u8>(3, 0x07),
+        std::make_tuple<size_t, u8>(4, 0x0f),
+        std::make_tuple<size_t, u8>(5, 0x1f),
+        std::make_tuple<size_t, u8>(6, 0x3f),
+        std::make_tuple<size_t, u8>(7, 0x7f),
+        std::make_tuple<size_t, u8>(8, 0xff),
+    };
+
+    for (const auto [count, expected] : cases) {
+        REQUIRE(mcl::bit::ones<u8>(count) == expected);
+        REQUIRE(mcl::bit::ones<u16>(count) == expected);
+        REQUIRE(mcl::bit::ones<u32>(count) == expected);
+        REQUIRE(mcl::bit::ones<u64>(count) == expected);
+        REQUIRE(mcl::bit::ones<uptr>(count) == expected);
+        REQUIRE(mcl::bit::ones<size_t>(count) == expected);
+    }
+}
+
+static_assert(mcl::bit::ones<3, u8>() == 0x7);
+static_assert(mcl::bit::ones<15, u16>() == 0x7fff);
+static_assert(mcl::bit::ones<16, u16>() == 0xffff);
+static_assert(mcl::bit::ones<31, u32>() == 0x7fff'ffff);
+static_assert(mcl::bit::ones<32, u32>() == 0xffff'ffff);
+static_assert(mcl::bit::ones<63, u64>() == 0x7fff'ffff'ffff'ffff);
+static_assert(mcl::bit::ones<64, u64>() == 0xffff'ffff'ffff'ffff);