bitstream.c

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/*
 * qrencode - QR Code encoder
 *
 * Binary sequence class.
 * Copyright (C) 2006-2017 Kentaro Fukuchi <kentaro@fukuchi.org>
 *
 * 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 "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "bitstream.h"

#define DEFAULT_BUFSIZE (128)

BitStream *BitStream_new(void)
{
    BitStream *bstream;

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

    bstream->length = 0;
    bstream->data = (unsigned char *)malloc(DEFAULT_BUFSIZE);
    if(bstream->data == NULL) {
        free(bstream);
        return NULL;
    }
    bstream->datasize = DEFAULT_BUFSIZE;

    return bstream;
}

#ifdef WITH_TESTS
BitStream *BitStream_newWithBits(size_t size, unsigned char *bits)
{
    BitStream *bstream;

    if(size == 0) return BitStream_new();

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

    bstream->data = (unsigned char *)malloc(size);
    if(bstream->data == NULL) {
        free(bstream);
        return NULL;
    }

    bstream->length = size;
    bstream->datasize = size;
    memcpy(bstream->data, bits, size);

    return bstream;
}
#endif

static int BitStream_expand(BitStream *bstream)
{
    unsigned char *data;

    data = (unsigned char *)realloc(bstream->data, bstream->datasize * 2);
    if(data == NULL) {
        return -1;
    }

    bstream->data = data;
    bstream->datasize *= 2;

    return 0;
}

static void BitStream_writeNum(unsigned char *dest, size_t bits, unsigned int num)
{
    unsigned int mask;
    size_t i;
    unsigned char *p;

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

static void BitStream_writeBytes(unsigned char *dest, size_t size, unsigned char *data)
{
    unsigned char mask;
    size_t i, j;
    unsigned char *p;

    p = dest;
    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;
        }
    }
}

int BitStream_append(BitStream *bstream, BitStream *arg)
{
    int ret;

    if(arg == NULL) {
        return -1;
    }
    if(arg->length == 0) {
        return 0;
    }

    while(bstream->length + arg->length > bstream->datasize) {
        ret = BitStream_expand(bstream);
        if(ret < 0) return ret;
    }

    memcpy(bstream->data + bstream->length, arg->data, arg->length);
    bstream->length += arg->length;

    return 0;
}

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

    if(bits == 0) return 0;

    while(bstream->datasize - bstream->length < bits) {
        ret = BitStream_expand(bstream);
        if(ret < 0) return ret;
    }
    BitStream_writeNum(bstream->data + bstream->length, bits, num);
    bstream->length += bits;

    return 0;
}

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

    if(size == 0) return 0;

    while(bstream->datasize - bstream->length < size * 8) {
        ret = BitStream_expand(bstream);
        if(ret < 0) return ret;
    }
    BitStream_writeBytes(bstream->data + bstream->length, size, data);
    bstream->length += size * 8;

    return 0;
}

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

    return data;
}

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