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bitstream.c

/*
 * qrencode - QR Code encoder
 *
 * Binary sequence class.
 * Copyright (C) 2006, 2007, 2008, 2009 Kentaro Fukuchi <fukuchi@megaui.net>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "bitstream.h"

BitStream *BitStream_new(void)
{
      BitStream *bstream;

      bstream = (BitStream *)malloc(sizeof(BitStream));
      if(bstream == NULL) return NULL;

      bstream->length = 0;
      bstream->data = NULL;

      return bstream;
}

static int BitStream_allocate(BitStream *bstream, int length)
{
      unsigned char *data;

      if(bstream == NULL) {
            return -1;
      }

      data = (unsigned char *)malloc(length);
      if(data == NULL) {
            return -1;
      }

      if(bstream->data) {
            free(bstream->data);
      }
      bstream->length = length;
      bstream->data = data;

      return 0;
}

static BitStream *BitStream_newFromNum(int bits, unsigned int num)
{
      unsigned int mask;
      int i;
      unsigned char *p;
      BitStream *bstream;

      bstream = BitStream_new();
      if(bstream == NULL) return NULL;

      if(BitStream_allocate(bstream, bits)) {
            BitStream_free(bstream);
            return NULL;
      }

      p = bstream->data;
      mask = 1 << (bits - 1);
      for(i=0; i<bits; i++) {
            if(num & mask) {
                  *p = 1;
            } else {
                  *p = 0;
            }
            p++;
            mask = mask >> 1;
      }

      return bstream;
}

static BitStream *BitStream_newFromBytes(int size, unsigned char *data)
{
      unsigned char mask;
      int i, j;
      unsigned char *p;
      BitStream *bstream;

      bstream = BitStream_new();
      if(bstream == NULL) return NULL;

      if(BitStream_allocate(bstream, size * 8)) {
            BitStream_free(bstream);
            return NULL;
      }

      p = bstream->data;
      for(i=0; i<size; i++) {
            mask = 0x80;
            for(j=0; j<8; j++) {
                  if(data[i] & mask) {
                        *p = 1;
                  } else {
                        *p = 0;
                  }
                  p++;
                  mask = mask >> 1;
            }
      }

      return bstream;
}

int BitStream_append(BitStream *bstream, BitStream *arg)
{
      unsigned char *data;

      if(arg == NULL) {
            return -1;
      }
      if(arg->length == 0) {
            return 0;
      }
      if(bstream->length == 0) {
            if(BitStream_allocate(bstream, arg->length)) {
                  return -1;
            }
            memcpy(bstream->data, arg->data, arg->length);
            return 0;
      }

      data = (unsigned char *)malloc(bstream->length + arg->length);
      if(data == NULL) {
            return -1;
      }
      memcpy(data, bstream->data, bstream->length);
      memcpy(data + bstream->length, arg->data, arg->length);

      free(bstream->data);
      bstream->length += arg->length;
      bstream->data = data;

      return 0;
}

int BitStream_appendNum(BitStream *bstream, int bits, unsigned int num)
{
      BitStream *b;
      int ret;

      if(bits == 0) return 0;

      b = BitStream_newFromNum(bits, num);
      if(b == NULL) return -1;

      ret = BitStream_append(bstream, b);
      BitStream_free(b);

      return ret;
}

int BitStream_appendBytes(BitStream *bstream, int size, unsigned char *data)
{
      BitStream *b;
      int ret;

      if(size == 0) return 0;

      b = BitStream_newFromBytes(size, data);
      if(b == NULL) return -1;

      ret = BitStream_append(bstream, b);
      BitStream_free(b);

      return ret;
}

unsigned char *BitStream_toByte(BitStream *bstream)
{
      int i, j, size, bytes;
      unsigned char *data, v;
      unsigned char *p;

      size = BitStream_size(bstream);
      if(size == 0) {
            return NULL;
      }
      data = (unsigned char *)malloc((size + 7) / 8);
      if(data == NULL) {
            return NULL;
      }

      bytes = size  / 8;

      p = bstream->data;
      for(i=0; i<bytes; i++) {
            v = 0;
            for(j=0; j<8; j++) {
                  v = v << 1;
                  v |= *p;
                  p++;
            }
            data[i] = v;
      }
      if(size & 7) {
            v = 0;
            for(j=0; j<(size & 7); j++) {
                  v = v << 1;
                  v |= *p;
                  p++;
            }
            data[bytes] = v;
      }

      return data;
}

void BitStream_free(BitStream *bstream)
{
      if(bstream != NULL) {
            free(bstream->data);
            free(bstream);
      }
}

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