/*

 * zlib_compress.c - compress with a zlib wrapper

 *

 * Copyright 2016 Eric Biggers

 *

 * Permission is hereby granted, free of charge, to any person

 * obtaining a copy of this software and associated documentation

 * files (the "Software"), to deal in the Software without

 * restriction, including without limitation the rights to use,

 * copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following

 * conditions:

 *

 * The above copyright notice and this permission notice shall be

 * included in all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES

 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT

 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,

 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR

 * OTHER DEALINGS IN THE SOFTWARE.

 */

#include "deflate_compress.h"

#include "zlib_constants.h"

LIBDEFLATEAPI size_t

libdeflate_zlib_compress(struct libdeflate_compressor *c,

       const void *in, size_t in_nbytes,

       void *out, size_t out_nbytes_avail)

{

  u8 *out_next = out;

  u16 hdr;

  unsigned compression_level;

  unsigned level_hint;

  size_t deflate_size;

  if (out_nbytes_avail <= ZLIB_MIN_OVERHEAD)

    return 0;

  /* 2 byte header: CMF and FLG  */

  hdr = (ZLIB_CM_DEFLATE << 8) | (ZLIB_CINFO_32K_WINDOW << 12);

  compression_level = libdeflate_get_compression_level(c);

  if (compression_level < 2)

    level_hint = ZLIB_FASTEST_COMPRESSION;

  else if (compression_level < 6)

    level_hint = ZLIB_FAST_COMPRESSION;

  else if (compression_level < 8)

    level_hint = ZLIB_DEFAULT_COMPRESSION;

  else

    level_hint = ZLIB_SLOWEST_COMPRESSION;

  hdr |= level_hint << 6;

  hdr |= 31 - (hdr % 31);

  put_unaligned_be16(hdr, out_next);

  out_next += 2;

  /* Compressed data  */

  deflate_size = libdeflate_deflate_compress(c, in, in_nbytes, out_next,

          out_nbytes_avail - ZLIB_MIN_OVERHEAD);

  if (deflate_size == 0)

    return 0;

  out_next += deflate_size;

  /* ADLER32  */

  put_unaligned_be32(libdeflate_adler32(1, in, in_nbytes), out_next);

  out_next += 4;

  return out_next - (u8 *)out;

}

LIBDEFLATEAPI size_t

libdeflate_zlib_compress_bound(struct libdeflate_compressor *c,

             size_t in_nbytes)

{

  return ZLIB_MIN_OVERHEAD +

         libdeflate_deflate_compress_bound(c, in_nbytes);

}