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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
commit | 26a029d407be480d791972afb5975cf62c9360a6 (patch) | |
tree | f435a8308119effd964b339f76abb83a57c29483 /js/src/builtin/temporal/Int96.cpp | |
parent | Initial commit. (diff) | |
download | firefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz firefox-26a029d407be480d791972afb5975cf62c9360a6.zip |
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'js/src/builtin/temporal/Int96.cpp')
-rw-r--r-- | js/src/builtin/temporal/Int96.cpp | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/js/src/builtin/temporal/Int96.cpp b/js/src/builtin/temporal/Int96.cpp new file mode 100644 index 0000000000..73ea5ce90e --- /dev/null +++ b/js/src/builtin/temporal/Int96.cpp @@ -0,0 +1,81 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- + * vim: set ts=8 sts=2 et sw=2 tw=80: + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include "builtin/temporal/Int96.h" + +#include "mozilla/Assertions.h" +#include "mozilla/Casting.h" +#include "mozilla/FloatingPoint.h" +#include "mozilla/Maybe.h" + +#include <cmath> +#include <stddef.h> +#include <stdint.h> + +#include "jsnum.h" + +using namespace js; +using namespace js::temporal; + +mozilla::Maybe<Int96> Int96::fromInteger(double value) { + MOZ_ASSERT(IsInteger(value)); + + // Fast path for the common case. + int64_t intValue; + if (mozilla::NumberEqualsInt64(value, &intValue)) { + return mozilla::Some(Int96{intValue}); + } + + // First double integer which requires more than three digits. + constexpr double maximum = 0x1p+96; + + // Reject if the value needs more than 96 bits. + if (std::abs(value) >= maximum) { + return mozilla::Nothing(); + } + + // Inlined version of |BigInt::createFromDouble()| for DigitBits=32. See the + // comments in |BigInt::createFromDouble()| for how this code works. + constexpr size_t DigitBits = 32; + + // The number can't have more than three digits when it's below |maximum|. + Int96::Digits digits = {}; + + int exponent = mozilla::ExponentComponent(value); + MOZ_ASSERT(0 <= exponent && exponent <= 95, + "exponent is lower than exponent of 0x1p+96"); + + int length = exponent / DigitBits + 1; + MOZ_ASSERT(1 <= length && length <= 3); + + using Double = mozilla::FloatingPoint<double>; + uint64_t mantissa = + mozilla::BitwiseCast<uint64_t>(value) & Double::kSignificandBits; + + // Add implicit high bit. + mantissa |= 1ull << Double::kSignificandWidth; + + // 0-indexed position of the double's most significant bit within the `msd`. + int msdTopBit = exponent % DigitBits; + + // First, build the MSD by shifting the mantissa appropriately. + int remainingMantissaBits = Double::kSignificandWidth - msdTopBit; + digits[--length] = mantissa >> remainingMantissaBits; + + // Fill in digits containing mantissa contributions. + mantissa = mantissa << (64 - remainingMantissaBits); + if (mantissa) { + MOZ_ASSERT(length > 0); + digits[--length] = uint32_t(mantissa >> 32); + + if (uint32_t(mantissa)) { + MOZ_ASSERT(length > 0); + digits[--length] = uint32_t(mantissa); + } + } + + return mozilla::Some(Int96{digits, value < 0}); +} |