// 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_BIT_WRITER_H_

#define LIB_JPEGLI_BIT_WRITER_H_

#include <stdint.h>

#include <string.h>

#include "lib/jpegli/common.h"

#include "lib/jxl/base/byte_order.h"

#include "lib/jxl/base/compiler_specific.h"

namespace jpegli {

// Handles the packing of bits into output bytes.

struct JpegBitWriter {

  j_compress_ptr cinfo;

  uint8_t* data;

  size_t len;

  size_t pos;

  size_t output_pos;

  uint64_t put_buffer;

  int free_bits;

  bool healthy;

};

void JpegBitWriterInit(j_compress_ptr cinfo);

bool EmptyBitWriterBuffer(JpegBitWriter* bw);

void JumpToByteBoundary(JpegBitWriter* bw);

// Returns non-zero if and only if x has a zero byte, i.e. one of

// x & 0xff, x & 0xff00, ..., x & 0xff00000000000000 is zero.

static JXL_INLINE uint64_t HasZeroByte(uint64_t x) {

  return (x - 0x0101010101010101ULL) & ~x & 0x8080808080808080ULL;

}

Unexecuted instantiation: common.cc:jpegli::HasZeroByte(unsigned long)

Unexecuted instantiation: color_transform.cc:jpegli::HasZeroByte(unsigned long)

/**

 * Writes the given byte to the output, writes an extra zero if byte is 0xFF.

 *

 * This method is "careless" - caller must make sure that there is enough

 * space in the output buffer. Emits up to 2 bytes to buffer.

 */

static JXL_INLINE void EmitByte(JpegBitWriter* bw, int byte) {

  bw->data[bw->pos++] = byte;

  if (byte == 0xFF) bw->data[bw->pos++] = 0;

}

Unexecuted instantiation: common.cc:jpegli::EmitByte(jpegli::JpegBitWriter*, int)

Unexecuted instantiation: color_transform.cc:jpegli::EmitByte(jpegli::JpegBitWriter*, int)

static JXL_INLINE void DischargeBitBuffer(JpegBitWriter* bw) {

  // At this point we are ready to emit the bytes of put_buffer to the output.

  // The JPEG format requires that after every 0xff byte in the entropy

  // coded section, there is a zero byte, therefore we first check if any of

  // the bytes of put_buffer is 0xFF.

  if (HasZeroByte(~bw->put_buffer)) {

    // We have a 0xFF byte somewhere, examine each byte and append a zero

    // byte if necessary.

    EmitByte(bw, (bw->put_buffer >> 56) & 0xFF);

    EmitByte(bw, (bw->put_buffer >> 48) & 0xFF);

    EmitByte(bw, (bw->put_buffer >> 40) & 0xFF);

    EmitByte(bw, (bw->put_buffer >> 32) & 0xFF);

    EmitByte(bw, (bw->put_buffer >> 24) & 0xFF);

    EmitByte(bw, (bw->put_buffer >> 16) & 0xFF);

    EmitByte(bw, (bw->put_buffer >> 8) & 0xFF);

    EmitByte(bw, (bw->put_buffer >> 0) & 0xFF);

  } else {

    // We don't have any 0xFF bytes, output all 8 bytes without checking.

    StoreBE64(bw->put_buffer, bw->data + bw->pos);

    bw->pos += 8;

  }

}

Unexecuted instantiation: common.cc:jpegli::DischargeBitBuffer(jpegli::JpegBitWriter*)

Unexecuted instantiation: color_transform.cc:jpegli::DischargeBitBuffer(jpegli::JpegBitWriter*)

static JXL_INLINE void WriteBits(JpegBitWriter* bw, int nbits, uint64_t bits) {

  // This is an optimization; if everything goes well,

  // then |nbits| is positive; if non-existing Huffman symbol is going to be

  // encoded, its length should be zero; later encoder could check the

  // "health" of JpegBitWriter.

  if (nbits == 0) {

    bw->healthy = false;

    return;

  }

  bw->free_bits -= nbits;

  if (bw->free_bits < 0) {

    bw->put_buffer <<= (bw->free_bits + nbits);

    bw->put_buffer |= (bits >> -bw->free_bits);

    DischargeBitBuffer(bw);

    bw->free_bits += 64;

    bw->put_buffer = nbits;

  }

  bw->put_buffer <<= nbits;

  bw->put_buffer |= bits;

}

Unexecuted instantiation: common.cc:jpegli::WriteBits(jpegli::JpegBitWriter*, int, unsigned long)

Unexecuted instantiation: color_transform.cc:jpegli::WriteBits(jpegli::JpegBitWriter*, int, unsigned long)

}  // namespace jpegli

#endif  // LIB_JPEGLI_BIT_WRITER_H_