mirror of
https://github.com/team-charls/charls
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bb7185254c
By design the benchmark project is not build as it relies on Google Benchmark that is retrieved using vcpkg. Vcpkg is now part of Visual Studio 2022, so building with VS 2022 works. One of the build steps of the CI pipeline build CharLS however with VS 2019 to ensure that VS 2019 still can be used. Enabled benchmark in the solution file for x86 and X64 would break VS 2019. ARM64 build are only support in VS 2022, so enabling that version doesn't break VS 2019.
103 lines
2.4 KiB
C++
103 lines
2.4 KiB
C++
// Copyright (c) Team CharLS.
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// SPDX-License-Identifier: BSD-3-Clause
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#pragma once
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#include "../src/regular_mode_context.hpp"
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#include <cassert>
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#include <cstdint>
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namespace charls {
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// Purpose: a JPEG-LS context with its current statistics.
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struct jls_context_v220 final
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{
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int32_t A{};
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int32_t B{};
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int16_t C{};
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int16_t N{1};
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jls_context_v220() = default;
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explicit jls_context_v220(const int32_t a) noexcept : A{a}
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{
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}
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[[nodiscard]]
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FORCE_INLINE int32_t get_error_correction(const int32_t k) const noexcept
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{
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if (k != 0)
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return 0;
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return bit_wise_sign(2 * B + N - 1);
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}
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/// <summary>Code segment A.12 – Variables update.</summary>
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FORCE_INLINE void update_variables(const int32_t error_value, const int32_t near_lossless, const int32_t reset_threshold)
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{
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ASSERT(N != 0);
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// For performance work on copies of A,B,N (compiler will use registers).
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int a{A + std::abs(error_value)};
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int b{B + error_value * (2 * near_lossless + 1)};
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int n{N};
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if (constexpr int limit{65536 * 256}; UNLIKELY(a >= limit || std::abs(b) >= limit))
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impl::throw_jpegls_error(jpegls_errc::invalid_data);
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if (n == reset_threshold)
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{
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a >>= 1;
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b >>= 1;
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n >>= 1;
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}
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A = a;
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++n;
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N = static_cast<int16_t>(n);
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if (b + n <= 0)
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{
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b = b + n;
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if (b <= -n)
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{
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b = -n + 1;
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}
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C = static_cast<int16_t>(C - static_cast<int16_t>(C > -128));
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}
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else if (b > 0)
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{
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b = b - n;
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if (b > 0)
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{
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b = 0;
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}
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C = static_cast<int16_t>(C + static_cast<int16_t>(C < 127));
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}
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B = b;
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ASSERT(N != 0);
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}
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/// <summary>
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/// <para>Computes the Golomb coding parameter using the algorithm as defined in ISO/IEC 14495-1, code segment A.10
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/// </para> <para>Original algorithm is: for (k = 0; (N[Q] << k) < A[Q]; k++) </para>
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/// </summary>
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[[nodiscard]]
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FORCE_INLINE int32_t get_golomb_coding_parameter() const
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{
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int32_t k{};
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for (; N << k < A && k < max_k_value; ++k)
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{
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}
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if (UNLIKELY(k == max_k_value))
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impl::throw_jpegls_error(jpegls_errc::invalid_data);
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return k;
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}
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};
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} // namespace charls
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