import catch2 3.8.1vendor/catch2/3.8.1vendor/catch2

1 files changed, 108 insertions, 0 deletions

diff --git a/src/catch2/internal/catch_floating_point_helpers.hpp b/src/catch2/internal/catch_floating_point_helpers.hpp
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+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+#ifndef CATCH_FLOATING_POINT_HELPERS_HPP_INCLUDED
+#define CATCH_FLOATING_POINT_HELPERS_HPP_INCLUDED
+
+#include <catch2/internal/catch_polyfills.hpp>
+
+#include <cassert>
+#include <cmath>
+#include <cstdint>
+#include <utility>
+#include <limits>
+
+namespace Catch {
+    namespace Detail {
+
+        uint32_t convertToBits(float f);
+        uint64_t convertToBits(double d);
+
+        // Used when we know we want == comparison of two doubles
+        // to centralize warning suppression
+        bool directCompare( float lhs, float rhs );
+        bool directCompare( double lhs, double rhs );
+
+    } // end namespace Detail
+
+
+
+#if defined( __GNUC__ ) || defined( __clang__ )
+#    pragma GCC diagnostic push
+    // We do a bunch of direct compensations of floating point numbers,
+    // because we know what we are doing and actually do want the direct
+    // comparison behaviour.
+#    pragma GCC diagnostic ignored "-Wfloat-equal"
+#endif
+
+    /**
+     * Calculates the ULP distance between two floating point numbers
+     *
+     * The ULP distance of two floating point numbers is the count of
+     * valid floating point numbers representable between them.
+     *
+     * There are some exceptions between how this function counts the
+     * distance, and the interpretation of the standard as implemented.
+     * by e.g. `nextafter`. For this function it always holds that:
+     * * `(x == y) => ulpDistance(x, y) == 0` (so `ulpDistance(-0, 0) == 0`)
+     * * `ulpDistance(maxFinite, INF) == 1`
+     * * `ulpDistance(x, -x) == 2 * ulpDistance(x, 0)`
+     *
+     * \pre `!isnan( lhs )`
+     * \pre `!isnan( rhs )`
+     * \pre floating point numbers are represented in IEEE-754 format
+     */
+    template <typename FP>
+    uint64_t ulpDistance( FP lhs, FP rhs ) {
+        assert( std::numeric_limits<FP>::is_iec559 &&
+            "ulpDistance assumes IEEE-754 format for floating point types" );
+        assert( !Catch::isnan( lhs ) &&
+                "Distance between NaN and number is not meaningful" );
+        assert( !Catch::isnan( rhs ) &&
+                "Distance between NaN and number is not meaningful" );
+
+        // We want X == Y to imply 0 ULP distance even if X and Y aren't
+        // bit-equal (-0 and 0), or X - Y != 0 (same sign infinities).
+        if ( lhs == rhs ) { return 0; }
+
+        // We need a properly typed positive zero for type inference.
+        static constexpr FP positive_zero{};
+
+        // We want to ensure that +/- 0 is always represented as positive zero
+        if ( lhs == positive_zero ) { lhs = positive_zero; }
+        if ( rhs == positive_zero ) { rhs = positive_zero; }
+
+        // If arguments have different signs, we can handle them by summing
+        // how far are they from 0 each.
+        if ( std::signbit( lhs ) != std::signbit( rhs ) ) {
+            return ulpDistance( std::abs( lhs ), positive_zero ) +
+                   ulpDistance( std::abs( rhs ), positive_zero );
+        }
+
+        // When both lhs and rhs are of the same sign, we can just
+        // read the numbers bitwise as integers, and then subtract them
+        // (assuming IEEE).
+        uint64_t lc = Detail::convertToBits( lhs );
+        uint64_t rc = Detail::convertToBits( rhs );
+
+        // The ulp distance between two numbers is symmetric, so to avoid
+        // dealing with overflows we want the bigger converted number on the lhs
+        if ( lc < rc ) {
+            std::swap( lc, rc );
+        }
+
+        return lc - rc;
+    }
+
+#if defined( __GNUC__ ) || defined( __clang__ )
+#    pragma GCC diagnostic pop
+#endif
+
+
+} // end namespace Catch
+
+#endif // CATCH_FLOATING_POINT_HELPERS_HPP_INCLUDED