bitwriter_buffer.c 1.45 KB
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/*
 *  Copyright (c) 2013 The WebM 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 in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

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#include <limits.h>
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#include <stdlib.h>
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#include "./vpx_config.h"
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#include "./bitwriter_buffer.h"
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size_t vpx_wb_bytes_written(const struct vpx_write_bit_buffer *wb) {
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  return wb->bit_offset / CHAR_BIT + (wb->bit_offset % CHAR_BIT > 0);
}

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void vpx_wb_write_bit(struct vpx_write_bit_buffer *wb, int bit) {
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  const int off = (int)wb->bit_offset;
  const int p = off / CHAR_BIT;
  const int q = CHAR_BIT - 1 - off % CHAR_BIT;
  if (q == CHAR_BIT -1) {
    wb->bit_buffer[p] = bit << q;
  } else {
    wb->bit_buffer[p] &= ~(1 << q);
    wb->bit_buffer[p] |= bit << q;
  }
  wb->bit_offset = off + 1;
}

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void vpx_wb_write_literal(struct vpx_write_bit_buffer *wb, int data, int bits) {
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  int bit;
  for (bit = bits - 1; bit >= 0; bit--)
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    vpx_wb_write_bit(wb, (data >> bit) & 1);
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}
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void vpx_wb_write_inv_signed_literal(struct vpx_write_bit_buffer *wb,
                                     int data, int bits) {
#if CONFIG_MISC_FIXES
  vpx_wb_write_literal(wb, data, bits + 1);
#else
  vpx_wb_write_literal(wb, abs(data), bits);
  vpx_wb_write_bit(wb, data < 0);
#endif
}