/src/libjxl/lib/jpegli/common_internal.h

Source
// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

#ifndef LIB_JPEGLI_COMMON_INTERNAL_H_
#define LIB_JPEGLI_COMMON_INTERNAL_H_

#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <hwy/aligned_allocator.h>

#include "lib/jpegli/memory_manager.h"
#include "lib/jpegli/simd.h"

namespace jpegli {

enum State {
  kDecNull,
  kDecStart,
  kDecInHeader,
  kDecHeaderDone,
  kDecProcessMarkers,
  kDecProcessScan,
  kEncNull,
  kEncStart,
  kEncHeader,
  kEncReadImage,
  kEncWriteCoeffs,
};

template <typename T1, typename T2>
constexpr inline T1 DivCeil(T1 a, T2 b) {
  return (a + b - 1) / b;
}

template <typename T1, typename T2>
constexpr inline T1 RoundUpTo(T1 a, T2 b) {
  return DivCeil(a, b) * b;
}

constexpr size_t kDCTBlockSize = 64;
// This is set to the same value as MAX_COMPS_IN_SCAN, because that is the
// maximum number of channels the libjpeg-turbo decoder can decode.
constexpr int kMaxComponents = 4;
constexpr int kMaxQuantTables = 4;
constexpr int kJpegPrecision = 8;
constexpr int kMaxHuffmanTables = 4;
constexpr size_t kJpegHuffmanMaxBitLength = 16;
constexpr int kJpegHuffmanAlphabetSize = 256;
constexpr int kJpegDCAlphabetSize = 12;
constexpr int kMaxDHTMarkers = 512;
constexpr int kMaxDimPixels = 65535;
constexpr uint8_t kApp1 = 0xE1;
constexpr uint8_t kApp2 = 0xE2;
const uint8_t kIccProfileTag[12] = "ICC_PROFILE";
const uint8_t kExifTag[6] = "Exif\0";
const uint8_t kXMPTag[29] = "http://ns.adobe.com/xap/1.0/";

/* clang-format off */
constexpr uint32_t kJPEGNaturalOrder[80] = {
  0,   1,  8, 16,  9,  2,  3, 10,
  17, 24, 32, 25, 18, 11,  4,  5,
  12, 19, 26, 33, 40, 48, 41, 34,
  27, 20, 13,  6,  7, 14, 21, 28,
  35, 42, 49, 56, 57, 50, 43, 36,
  29, 22, 15, 23, 30, 37, 44, 51,
  58, 59, 52, 45, 38, 31, 39, 46,
  53, 60, 61, 54, 47, 55, 62, 63,
  // extra entries for safety in decoder
  63, 63, 63, 63, 63, 63, 63, 63,
  63, 63, 63, 63, 63, 63, 63, 63
};

constexpr uint32_t kJPEGZigZagOrder[64] = {
  0,   1,  5,  6, 14, 15, 27, 28,
  2,   4,  7, 13, 16, 26, 29, 42,
  3,   8, 12, 17, 25, 30, 41, 43,
  9,  11, 18, 24, 31, 40, 44, 53,
  10, 19, 23, 32, 39, 45, 52, 54,
  20, 22, 33, 38, 46, 51, 55, 60,
  21, 34, 37, 47, 50, 56, 59, 61,
  35, 36, 48, 49, 57, 58, 62, 63
};
/* clang-format on */

template <typename T>
class RowBuffer {
 public:
  template <typename CInfoType>
  void Allocate(CInfoType cinfo, size_t num_rows, size_t rowsize) {
    static_assert(sizeof(T) == 4, "4-byte T is assumed");
    size_t vec_size = std::max(VectorSize(), sizeof(T));
    size_t alignment = std::max<size_t>(HWY_ALIGNMENT, vec_size);
    size_t min_memstride = alignment + rowsize * sizeof(T) + vec_size;
    size_t memstride = RoundUpTo(min_memstride, alignment);
    xsize_ = rowsize;
    ysize_ = num_rows;
    stride_ = memstride / sizeof(T);
    offset_ = alignment / sizeof(T);
    data_ = ::jpegli::Allocate<T>(cinfo, ysize_ * stride_, JPOOL_IMAGE_ALIGNED);
  }

  T* Row(ptrdiff_t y) const {
    return &data_[((ysize_ + y) % ysize_) * stride_ + offset_];
  }

  size_t xsize() const { return xsize_; };
  size_t ysize() const { return ysize_; };
  size_t stride() const { return stride_; }

  void PadRow(size_t y, size_t from, int border) {
    float* row = Row(y);
    for (int offset = -border; offset < 0; ++offset) {
      row[offset] = row[0];
    }
    float last_val = row[from - 1];
    for (size_t x = from; x < xsize_ + border; ++x) {
      row[x] = last_val;
    }
  }

  void CopyRow(ptrdiff_t dst_row, ptrdiff_t src_row, int border) {
    memcpy(Row(dst_row) - border, Row(src_row) - border,
           (xsize_ + 2 * border) * sizeof(T));
  }

  void FillRow(ptrdiff_t y, T val, size_t len) {
    T* row = Row(y);
    for (size_t x = 0; x < len; ++x) {
      row[x] = val;
    }
  }

 private:
  size_t xsize_;
  size_t ysize_;
  size_t stride_;
  size_t offset_;
  T* data_;
};

}  // namespace jpegli

#endif  // LIB_JPEGLI_COMMON_INTERNAL_H_

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Created: 2025-11-16 07:14