bhlib-old/src/bigint.c

#include <bh/internal/bigint.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>

static size_t bh_bigint_type_clz(BH_BIGINT_TYPE x)
{
    static const bh_uint8_t lookup[256] = {
        8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
        3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
        2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
        2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
    };

    size_t i, tmp;

    for (i = 0; i < BH_BIGINT_BITS / 8 + 1; i++)
    {
        tmp = (x >> (BH_BIGINT_BITS - 7)) & 0xFF;

        if (tmp)
            return lookup[tmp] + 8 * i - 1;

        x <<= 8;
    }

    return BH_BIGINT_BITS;
}

static size_t bh_bigint_type_log2(BH_BIGINT_TYPE x)
{
    static const bh_uint8_t lookup[256] = {
        0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
        4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
        5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
        5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
        6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
        6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
        6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
        6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
        7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
        7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
        7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
        7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
        7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
        7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
        7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
        7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
    };

    size_t i, tmp;

    for (i = 0; i < BH_BIGINT_BITS / 8 + 1; i++)
    {
        tmp = (x >> (BH_BIGINT_BITS - 7)) & 0xFF;
        if (tmp)
            return ((BH_BIGINT_BITS + 1) - 8 * (i + 1)) + lookup[tmp];

        x <<= 8;
    }

    return 0;
}

bh_bigint_t *bh_bigint_new(void)
{
    bh_bigint_t *result;

    result = malloc(sizeof(*result));
    if (result)
        bh_bigint_init(result);

    return result;
}

void bh_bigint_free(bh_bigint_t *bigint)
{
    bh_bigint_destroy(bigint);
    free(bigint);
}

void bh_bigint_init(bh_bigint_t *bigint)
{
    bigint->data = NULL;
    bigint->capacity = 0;
    bh_bigint_clear(bigint);
}

void bh_bigint_destroy(bh_bigint_t *bigint)
{
    if (bigint->data)
        free(bigint->data);
}

int bh_bigint_block(void)
{
    return BH_BIGINT_BITS;
}

int bh_bigint_clear(bh_bigint_t *bigint)
{
    bigint->error = 0;
    bigint->size = 0;
    bigint->type = 0;

    return BH_OK;
}

int bh_bigint_set(bh_bigint_t* to,
                  bh_bigint_t* from)
{
    /* Shortcut - one of the arguments has error flag set */
    if (from->error)
    {
        to->error = 1;
        return BH_ERROR;
    }

    /* Clear up result error flag */
    to->error = 0;

    /* Reserve space for big integer data */
    if (to->capacity < from->size)
    {
        if (bh_bigint_reserve(to, from->size))
        {
            to->error = 1;
            return BH_OOM;
        }
    }

    /* Copy data */
    memmove(to->data, from->data, sizeof(*from->data) * from->size);

    /* Set fields */
    to->size = from->size;
    to->type = from->type;

    return BH_OK;
}

/*
 * Universal implementation of set.
 *
 * This function:
 *  - determines sign of the input integer
 *  - reserves space in target big integer
 *  - copies data in little-endian like format
 */
#define BH_BIGINT_SET_BODY(to, from) \
    size_t size; \
    bh_bigint_clear((to)); \
    if ((from) < 0) { (to)->type = -1; (from) = -(from); } \
    else if ((from) == 0) { (to)->type = 0; return BH_OK; } \
    else (to)->type = 1; \
    if ((to)->capacity < (64 / BH_BIGINT_BITS + 1)) \
    { \
        if (bh_bigint_reserve((to), (64 / BH_BIGINT_BITS + 1))) \
        { \
            (to)->error = 1; \
            return BH_OOM; \
        } \
    } \
    for (size = 0; (from); size++) \
    { \
        (to)->data[size] = (from) & BH_BIGINT_MASK; \
        (from) >>= BH_BIGINT_BITS; \
    } \
    (to)->size = size; \
    return BH_OK;

/*
 * Universal implementation of get.
 *
 * This function:
 *  - copies blocks from the most to less significant units
 *  - left shifts result by unit bit width - 1
 */
#define BH_BIGINT_GET_BODY(from, rtype) \
    size_t i; \
    rtype result = 0; \
    if ((from)->error) return 0; \
    for (i = (from)->size; i > 0; i--) \
    { \
        result <<= BH_BIGINT_BITS; \
        result += (from)->data[i - 1]; \
    } \
    result *= (from)->type; \
    return result; \

int bh_bigint_set_int(bh_bigint_t *to,
                      int from)
{
    BH_BIGINT_SET_BODY(to, from);
}

int bh_bigint_set_uint(bh_bigint_t *to,
                       unsigned int from)
{
    BH_BIGINT_SET_BODY(to, from);
}

int bh_bigint_get_int(bh_bigint_t *bigint)
{
    BH_BIGINT_GET_BODY(bigint, int);
}

unsigned int bh_bigint_get_uint(bh_bigint_t *bigint)
{
    BH_BIGINT_GET_BODY(bigint, unsigned int);
}

int bh_bigint_set_int8(bh_bigint_t *to,
                       bh_int8_t from)
{
    BH_BIGINT_SET_BODY(to, from);
}

int bh_bigint_set_uint8(bh_bigint_t *to,
                        bh_uint8_t from)
{
    BH_BIGINT_SET_BODY(to, from);
}

bh_int8_t bh_bigint_get_int8(bh_bigint_t *bigint)
{
    BH_BIGINT_GET_BODY(bigint, bh_int8_t);
}

bh_uint8_t bh_bigint_get_uint8(bh_bigint_t *bigint)
{
    BH_BIGINT_GET_BODY(bigint, bh_uint8_t);
}

int bh_bigint_set_int16(bh_bigint_t *to,
                        bh_int16_t from)
{
    BH_BIGINT_SET_BODY(to, from);
}

int bh_bigint_set_uint16(bh_bigint_t *to,
                         bh_uint16_t from)
{
    BH_BIGINT_SET_BODY(to, from);
}

bh_int16_t bh_bigint_get_int16(bh_bigint_t *bigint)
{
    BH_BIGINT_GET_BODY(bigint, bh_int16_t);
}

bh_uint16_t bh_bigint_get_uint16(bh_bigint_t *bigint)
{
    BH_BIGINT_GET_BODY(bigint, bh_uint16_t);
}

int bh_bigint_set_int32(bh_bigint_t *to,
                         bh_int32_t from)
{
    BH_BIGINT_SET_BODY(to, from);
}

int bh_bigint_set_uint32(bh_bigint_t *to,
                         bh_uint32_t from)
{
    BH_BIGINT_SET_BODY(to, from);
}

bh_int32_t bh_bigint_get_int32(bh_bigint_t *bigint)
{
    BH_BIGINT_GET_BODY(bigint, bh_int32_t);
}

bh_uint32_t bh_bigint_get_uint32(bh_bigint_t *bigint)
{
    BH_BIGINT_GET_BODY(bigint, bh_uint32_t);
}

int bh_bigint_set_int64(bh_bigint_t *to,
                        bh_int64_t from)
{
    BH_BIGINT_SET_BODY(to, from);
}

int bh_bigint_set_uint64(bh_bigint_t *to,
                         bh_uint64_t from)
{
    BH_BIGINT_SET_BODY(to, from);
}

bh_int64_t bh_bigint_get_int64(bh_bigint_t *bigint)
{
    BH_BIGINT_GET_BODY(bigint, bh_int64_t);
}

bh_uint64_t bh_bigint_get_uint64(bh_bigint_t *bigint)
{
    BH_BIGINT_GET_BODY(bigint, bh_uint64_t);
}

size_t bh_bigint_capacity(bh_bigint_t *bigint)
{
    return bigint->capacity;
}

size_t bh_bigint_length(bh_bigint_t *bigint)
{
    return bigint->size;
}

int bh_bigint_reserve(bh_bigint_t *bigint,
                      size_t size)
{
    void *data;

    /* Initialize variables */
    data = NULL;

    /* New capacity can't be lower than current big integer size */
    if (size < bigint->size)
        size = bigint->size;

    /* Prevent same size reallocation */
    if (size == bigint->size)
        return BH_OK;

    if (size)
    {
        /* Allocate memory for the new digit storage */
        data = malloc(sizeof(*bigint->data) * size);
        if (!data)
            return BH_OOM;

        /* Copy existing data */
        if (bigint->size)
            memmove(data, bigint->data, sizeof(*bigint->data) * bigint->size);
    }

    /* If big integer had existing data - free it */
    if (bigint->data)
        free(bigint->data);

    /* Update fields */
    bigint->data = data;
    bigint->capacity = size;

    return BH_OK;
}

static int bh_bigint_add_base(bh_bigint_t *to,
                              bh_bigint_t *most,
                              bh_bigint_t *least)
{
    BH_BIGINT_TYPE carry, tmp;
    size_t i;

    /* Clear up result error flag */
    to->error = 0;

    /* Reserve space for output */
    if (to->capacity < most->size + 1)
    {
        if (bh_bigint_reserve(to, most->size + 1))
        {
            to->error = 1;
            return BH_OOM;
        }
    }

    /* Reset carry value */
    carry = 0;

    /* Main addition loop */
    for (i = 0; i < least->size; i++)
    {
        tmp = most->data[i] + least->data[i] + carry;
        carry = tmp >> BH_BIGINT_BITS;
        to->data[i] = tmp & BH_BIGINT_MASK;
    }

    /* Carry propogation loop */
    for (; i < most->size; i++)
    {
        tmp = most->data[i] + carry;
        carry = tmp >> BH_BIGINT_BITS;
        to->data[i] = tmp & BH_BIGINT_MASK;
    }

    /* Write carry value and update result size */
    to->data[i] = carry;

    if (carry)
        to->size = most->size + 1;
    else
        to->size = most->size;

    return BH_OK;
}

static int bh_bigint_sub_base(bh_bigint_t *to,
                              bh_bigint_t *most,
                              bh_bigint_t *least)
{
    BH_BIGINT_TYPE carry, tmp;
    size_t size, i;

    /* Clear up result error flag */
    to->error = 0;

    /* Reserve space for output */
    if (to->capacity < most->size)
    {
        if (bh_bigint_reserve(to, most->size))
        {
            to->error = 1;
            return BH_OOM;
        }
    }

    /* Reset carry and size value */
    carry = 0;
    size = 0;

    /* Main subtraction loop */
    for (i = 0; i < least->size; i++)
    {
        tmp = most->data[i] - least->data[i] - carry;
        carry = tmp >> BH_BIGINT_BITS;
        to->data[i] = tmp & BH_BIGINT_MASK;

        if (to->data[i])
            size = i + 1;
    }

    /* Carry propogation loop */
    for (; i < most->size; i++)
    {
        tmp = most->data[i] - carry;
        carry = tmp >> BH_BIGINT_BITS;
        to->data[i] = tmp & BH_BIGINT_MASK;

        if (to->data[i])
            size = i + 1;
    }

    /* Update result size */
    to->size = size;
    to->error = 0;

    return BH_OK;
}

int bh_bigint_add(bh_bigint_t *to,
                  bh_bigint_t *left,
                  bh_bigint_t *right)
{
    bh_bigint_t *least, *most;
    int type, code;

    /* Shortcut - one of the arguments has error flag set */
    if (left->error || right->error)
    {
        to->error = 1;
        return BH_ERROR;
    }

    /* Determine most and least numbers */
    if (bh_bigint_equal_mod(left, right) >= 0)
    {
        most = left;
        least = right;
        type = left->type;
    }
    else
    {
        most = right;
        least = left;
        type = right->type;
    }

    /* Perform addition or subtraction */
    if (most->type == least->type)
        code = bh_bigint_add_base(to, most, least);
    else
        code = bh_bigint_sub_base(to, most, least);

    if (!code)
    {
        /* Set result sign or zero */
        if (to->size)
            to->type = type;
        else
            to->type = 0;
    }

    /* Return result code */
    return code;
}

int bh_bigint_sub(bh_bigint_t *to,
                  bh_bigint_t *left,
                  bh_bigint_t *right)
{
    bh_bigint_t *least, *most;
    int type, code;

    /* Shortcut - one of the arguments has error flag set */
    if (left->error || right->error)
    {
        to->error = 1;
        return BH_ERROR;
    }

    /* Determine most and least numbers */
    if (bh_bigint_equal_mod(left, right) >= 0)
    {
        most = left;
        least = right;
        type = left->type;
    }
    else
    {
        most = right;
        least = left;
        type = right->type * -1;
    }

    /* Perform addition or subtraction */
    if (most->type == least->type)
        code = bh_bigint_sub_base(to, most, least);
    else
        code = bh_bigint_add_base(to, most, least);

    if (!code)
    {
        /* Set result sign or zero */
        if (to->size)
            to->type = type;
        else
            to->type = 0;
    }

    /* Return result code */
    return code;
}

int bh_bigint_mul(bh_bigint_t *to,
                  bh_bigint_t *left,
                  bh_bigint_t *right)
{
    bh_bigint_t *result;
    BH_BIGINT_TYPE carry;
    BH_BIGINT_TMP tmp;
    size_t i, j, size;

    /* Shortcut - one of the arguments has error flag set */
    if (left->error || right->error)
    {
        to->error = 1;
        return BH_ERROR;
    }

    /* Clear up result error flag */
    to->error = 0;

    /* Shortcut - multiplication by zero */
    if (left->type == 0 || right->type == 0)
    {
        to->type = 0;
        to->size = 0;
        return BH_OK;
    }

    /* If to is left or right argument - allocate temporary storage */
    result = to;
    if (to == left || to == right)
    {
        result = bh_bigint_new();
        if (!result)
        {
            to->error = 1;
            return BH_OOM;
        }
    }

    /* Reserve space for result */
    if (result->capacity < (left->size + right->size + 1))
    {
        if (bh_bigint_reserve(result, left->size + right->size + 1))
        {
            to->error = 1;
            return BH_OOM;
        }
    }

    /* Clear the result array */
    memset(result->data, 0, sizeof(*result->data) * (left->size + right->size));

    /* Prepare variables */
    size = 0;

    /* Multiplication loop */
    for (i = 0; i < left->size; i++)
    {
        carry = 0;
        for (j = 0; j < right->size; j++)
        {
            tmp = (BH_BIGINT_TMP)left->data[i] * (BH_BIGINT_TMP)right->data[j];
            tmp += carry + result->data[j + i];
            carry = tmp >> BH_BIGINT_BITS;
            result->data[j + i] = tmp & BH_BIGINT_MASK;
        }

        result->data[j + i] = carry;
    }

    /* Truncate multiplication result size */
    size = left->size + right->size;
    while (size && !result->data[size - 1]) size--;

    /* Determine sign */
    if (left->type != right->type)
        result->type = -1;
    else
        result->type = 1;

    /* Update size */
    result->size = size;

    /* If tmp is temporary storage - copy data back and deallocate */
    if (result != to)
    {
        bh_bigint_set(to, result);
        bh_bigint_free(result);
    }

    return BH_OK;
}

int bh_bigint_mul_digit(bh_bigint_t *to,
                        bh_bigint_t *left,
                        bh_int16_t right)
{
    BH_BIGINT_TYPE carry;
    BH_BIGINT_TMP tmp;
    size_t i, size;

    /* Shortcut - one of the arguments has error flag set */
    if (left->error)
    {
        to->error = 1;
        return BH_ERROR;
    }

    /* Clear up result error flag */
    to->error = 0;

    /* Shortcut - multiplication by zero */
    if (left->type == 0 || right == 0)
    {
        to->type = 0;
        to->size = 0;
        return BH_OK;
    }

    /* Reserve space for result */
    if (to->capacity < (left->size + 1))
    {
        if (bh_bigint_reserve(to, left->size + 1))
        {
            to->error = 1;
            return BH_OOM;
        }
    }

    /* Determine sign */
    if ((left->type > 0 && right < 0) || (left->type < 0 && right > 0))
        to->type = -1;
    else
        to->type = 1;

    if (right < 0)
        right = -right;

    /* Prepare variables */
    carry = 0;

    /* Multiplication loop */
    for (i = 0; i < left->size; i++)
    {
        tmp = (BH_BIGINT_TMP)left->data[i] * (BH_BIGINT_TMP)right + carry;
        carry = tmp >> BH_BIGINT_BITS;
        to->data[i] = tmp & BH_BIGINT_MASK;
    }
    to->data[i] = carry;

    /* Truncate multiplication result size */
    size = left->size + 1;
    while (size && !to->data[size - 1]) size--;

    /* Update size */
    to->size = size;

    return BH_OK;
}

int bh_bigint_pow(bh_bigint_t *to,
                  bh_bigint_t *from,
                  bh_uint32_t power)
{
    bh_bigint_t *base;
    int code, type;

    /* Initialize variables */
    base = NULL;
    code = BH_OK;

    /* Shortcut - one of the arguments has error flag set */
    if (from->error)
    {
        to->error = 1;
        return BH_ERROR;
    }

    /* Clear up result error flag */
    to->error = 0;

    /* Shortcut - power is equal to 0 */
    if (!power)
        return bh_bigint_set_int(to, 1);

    /* Shortcut - value is 0 */
    if (bh_bigint_is_zero(from))
        return bh_bigint_clear(to);

    /* Determine sign */
    if (from->type < 0 && power & 0x1)
        type = -1;
    else
        type = 1;

    /* Setup base variable */
    base = bh_bigint_new();
    if (!base || bh_bigint_set(base, from))
    {
        to->error = 1;
        code = BH_OOM;
        goto finish;
    }

    if (bh_bigint_set_int(to, 1))
    {
        to->error = 1;
        code = BH_OOM;
        goto finish;
    }

    /* Perform exponentiation by squaring */
    while (power)
    {
        if (power & 0x1)
            bh_bigint_mul(to, to, base);

        bh_bigint_mul(base, base, base);
        power >>= 1;

        /* Stop if error occured */
        if (base->error || to->error)
        {
            to->error = 1;
            code = BH_ERROR;
            break;
        }
    }

    /* Fix the sign */
    to->type = type;

finish:
    /* Free internal variables */
    if (base)
        bh_bigint_free(base);

    return code;
}

int bh_bigint_powm(bh_bigint_t *to,
                   bh_bigint_t *left,
                   bh_bigint_t *right,
                   bh_bigint_t *mod)
{
    bh_bigint_t *result, *base, *exponent;
    int code, type;

    /* Initialize variables */
    result = NULL; base = NULL; exponent = NULL;
    code = BH_OK;

    /* Shortcut - one of the arguments has error flag set */
    if (left->error || right->error || mod->error)
    {
        to->error = 1;
        return BH_ERROR;
    }

    /* Clear up result error flag */
    to->error = 0;

    /* Shortcut - power is equal to 0 */
    if (bh_bigint_is_zero(right))
        return bh_bigint_set_int(to, 1);

    /* Shortcut - value is 0 */
    if (bh_bigint_is_zero(left))
        return bh_bigint_clear(to);

    /* Shortcut - power is negative */
    if (bh_bigint_is_negative(right))
        return bh_bigint_clear(to);

    /* Figure out result sign */
    if (left->type < 0 && right->data[0] & 0x1)
        type = -1;
    else
        type = 1;

    /* Setup result variable */
    result = to;
    if (to == mod)
    {
        result = bh_bigint_new();
        if (!result)
        {
            to->error = 1;
            code = BH_OOM;
            goto finish;
        }
    }

    /* Reserve space for result */
    if (bh_bigint_reserve(result, mod->size * 2 + 1) || bh_bigint_set_int(result, 1))
    {
        to->error = 1;
        code = BH_OOM;
        goto finish;
    }

    /* Setup base variable */
    base = bh_bigint_new();
    if (!base || bh_bigint_reserve(base, mod->size * 2 + 1))
    {
        to->error = 1;
        code = BH_OOM;
        goto finish;
    }

    if (bh_bigint_mod(base, left, mod))
    {
        to->error = 1;
        code = BH_OOM;
        goto finish;
    }

    /* Setup exponent variable */
    exponent = bh_bigint_new();
    if (!exponent || bh_bigint_set(exponent, right))
    {
        to->error = 1;
        code = BH_OOM;
        goto finish;
    }

    /* Perform exponentiation by squaring */
    while (!bh_bigint_is_zero(exponent))
    {
        if (exponent->data[0] & 0x1)
        {
            bh_bigint_mul(result, result, base);
            bh_bigint_mod(result, result, mod);
        }
        bh_bigint_mul(base, base, base);
        bh_bigint_mod(base, base, mod);
        bh_bigint_rsh(exponent, exponent, 1);

        /* Stop if error occured */
        if (base->error || result->error)
        {
            to->error = 1;
            code = BH_ERROR;
            break;
        }
    }

    /* Fix the sign */
    result->type = type;

finish:
    /* Free internal variables */
    if (base)
        bh_bigint_free(base);
    if (exponent)
        bh_bigint_free(exponent);
    if (result && result != to)
    {
        bh_bigint_set(to, result);
        bh_bigint_free(result);
    }

    return code;
}

static BH_BIGINT_TYPE bh_bigint_div_guess(bh_bigint_t *left,
                                          bh_bigint_t *right)
{
    BH_BIGINT_TMP tmp;

    /* Left is bigger then right */
    if (bh_bigint_equal_mod(left, right) < 0)
        return 0;

    /* Make a guess */
    tmp = left->data[left->size - 1];

    if (left->size != right->size)
        tmp = (tmp << BH_BIGINT_BITS) + left->data[left->size - 2];

    return tmp / right->data[right->size - 1];
}

static int bh_bigint_div_base(bh_bigint_t *quotient,
                              bh_bigint_t *remainder,
                              bh_bigint_t *left,
                              bh_bigint_t *right,
                              int *shift)
{
    bh_bigint_t *nleft, *nright, *tmp;
    BH_BIGINT_TYPE q;
    int code;

    /* Initialize variables */
    nleft = NULL; nright = NULL; tmp = NULL;
    code = BH_OK;

    /* Clear up result error flags */
    if (quotient)
        quotient->error = 0;
    remainder->error = 0;

    /* Allocate space for normilized versions of integers and temporary */
    nleft = bh_bigint_new();
    if (!nleft || bh_bigint_reserve(nleft, left->size + 1))
    {
        if (quotient)
            quotient->error = 1;
        remainder->error = 1;
        code = BH_OOM;
        goto finish;
    }

    nright = bh_bigint_new();
    if (!nright || bh_bigint_reserve(nright, right->size + 1))
    {
        if (quotient)
            quotient->error = 1;
        remainder->error = 1;
        code = BH_OOM;
        goto finish;
    }

    tmp = bh_bigint_new();
    if (!tmp || bh_bigint_reserve(tmp, left->size))
    {
        if (quotient)
            quotient->error = 1;
        remainder->error = 1;
        code = BH_OOM;
        goto finish;
    }

    /* Allocate space for remainder and quotient */
    if (quotient && (quotient->capacity < left->size + 1))
    {
        if (bh_bigint_reserve(quotient, left->size + 1))
        {
            if (quotient)
                quotient->error = 1;
            remainder->error = 1;
            code = BH_OOM;
            goto finish;
        }
    }

    if (remainder->capacity < left->size + 1)
    {
        if (bh_bigint_reserve(remainder, left->size + 1))
        {
            if (quotient)
                quotient->error = 1;
            remainder->error = 1;
            code = BH_OOM;
            goto finish;
        }
    }

    /* Normilize integers */
    *shift = bh_bigint_type_clz(right->data[right->size - 1]);
    bh_bigint_lsh(nleft, left, *shift);
    bh_bigint_lsh(nright, right, *shift);

    /* Reset quotient and remainder. */
    if (quotient)
        bh_bigint_set_int(quotient, 0);
    bh_bigint_set_int(remainder, 0);

    /* Get as many digits from nleft so that remainder >= right */
    while (bh_bigint_equal_mod(remainder, nright) < 0)
    {
        bh_bigint_lsh(remainder, remainder, BH_BIGINT_BITS);
        remainder->data[0] = nleft->data[nleft->size - 1];
        if (!remainder->size)
        {
            remainder->size = 1;
            remainder->type = 1;
        }
        nleft->size--;
    }

    while (1)
    {
        /* Make a guess at what first digit of quotient should be */
        q = bh_bigint_div_guess(remainder, nright);

        tmp->size = 1;
        tmp->type = 1;
        tmp->data[0] = q;
        bh_bigint_mul(tmp, nright, tmp);

        /* Decriment quotient digit if our guess was wrong */
        while (bh_bigint_equal_mod(remainder, tmp) < 0)
        {
            q--;
            tmp->size = 1;
            tmp->type = 1;
            tmp->data[0] = q;
            bh_bigint_mul(tmp, nright, tmp);
        }

        /* Append guessed digit to quotient (if needed) */
        if (quotient)
        {
            bh_bigint_lsh(quotient, quotient, BH_BIGINT_BITS);
            quotient->data[0] = q;
            if (!quotient->size)
            {
                quotient->size = 1;
                quotient->type = 1;
            }
        }

        /* Calculate remainder */
        /* Prevent using addition logic and use subtraction */
        bh_bigint_sub_base(remainder, remainder, tmp);

        if (!nleft->size)
            break;

        /* Fetch remaining digit from nleft */
        bh_bigint_lsh(remainder, remainder, BH_BIGINT_BITS);
        remainder->data[0] = nleft->data[nleft->size - 1];
        if (!remainder->size)
        {
            remainder->size = 1;
            remainder->type = 1;
        }
        nleft->size--;
    }

finish:
    if (nleft)
        bh_bigint_free(nleft);
    if (nright)
        bh_bigint_free(nright);
    if (tmp)
        bh_bigint_free(tmp);

    return code;
}

/**
 * This follows C99 model (a/b)*b + a%b
 */
int bh_bigint_divmod(bh_bigint_t *quotient,
                     bh_bigint_t *remainder,
                     bh_bigint_t *left,
                     bh_bigint_t *right)
{
    int shift, code, type;
    bh_bigint_t *tmp;

    /* Shortcut - one of the arguments has error flag set */
    if (left->error || right->error)
    {
        if (quotient)
            quotient->error = 1;
        if (remainder)
            remainder->error = 1;
        return BH_ERROR;
    }

    /* Clear up result error flags */
    if (quotient)
        quotient->error = 0;
    if (remainder)
        remainder->error = 0;

    /* Shortcut - left is zero - result is zero */
    if (left->type == 0)
    {
        if (quotient)
            bh_bigint_clear(quotient);
        if (remainder)
            bh_bigint_clear(remainder);

        return BH_OK;
    }

    /* Shortcut - division by zero */
    if (right->type == 0)
    {
        if (quotient)
            quotient->error = 1;
        if (remainder)
            remainder->error = 1;
        return BH_ERROR;
    }

    /* Shortcut - left is less then right - quotient is zero, remainder is left */
    if (bh_bigint_equal_mod(left, right) < 0)
    {
        if (remainder && bh_bigint_set(remainder, left))
        {
            if (quotient)
                quotient->error = 1;
            remainder->error = 1;
            return BH_OOM;
        }

        if (quotient && bh_bigint_clear(quotient))
        {
            quotient->error = 1;
            if (remainder)
                remainder->error = 1;
            return BH_OOM;
        }

        return BH_OK;
    }

    /* Figure out result sign */
    if (left->type != right->type)
        type = -1;
    else
        type = 1;

    /* Make sure we have remainder as our working buffer */
    tmp = remainder;
    if (!remainder)
    {
        tmp = bh_bigint_new();
        if (!tmp)
        {
            if (quotient)
                quotient->error = 1;
            if (remainder)
                remainder->error = 1;
            return BH_OOM;
        }
    }

    code = bh_bigint_div_base(quotient, tmp, left, right, &shift);
    if (!code)
    {
        /* Remainder should use sign of the left operand */
        tmp->type = left->type;

        /* If remainder required - normilize it */
        if (tmp == remainder)
            bh_bigint_rsh(remainder, remainder, shift);

        /* Fix the sign */
        if (quotient)
            quotient->type = type;
    }

    if (tmp != remainder)
        bh_bigint_free(tmp);

    return code;
}

int bh_bigint_div(bh_bigint_t *to,
                  bh_bigint_t *left,
                  bh_bigint_t *right)
{
    return bh_bigint_divmod(to, NULL, left, right);
}

int bh_bigint_mod(bh_bigint_t *to,
                  bh_bigint_t *left,
                  bh_bigint_t *right)
{
    return bh_bigint_divmod(NULL, to, left, right);
}

int bh_bigint_lsh(bh_bigint_t *to,
                  bh_bigint_t *left,
                  bh_uint32_t shift)
{
    size_t i, bits, blocks;
    BH_BIGINT_TYPE tmp;

    /* Shortcut - one of the arguments has error flag set */
    if (left->error)
    {
        to->error = 1;
        return BH_ERROR;
    }

    /* Clear up result error flag */
    to->error = 0;

    /* Calculate distance in blocks and bits */
    blocks = shift / BH_BIGINT_BITS;
    bits = shift % BH_BIGINT_BITS;

    /* Shortcut - initial value is zero */
    if (left->type == 0)
    {
        to->type = 0;
        to->size = 0;
        return BH_OK;
    }

    /* Check if shift is block aligned */
    if (bits)
    {
        /* Shift is not block aligned - reserve space for 1 additional block */
        if (to->capacity < left->size + blocks + 1)
        {
            if (bh_bigint_reserve(to, left->size + blocks + 1))
            {
                to->error = 1;
                return BH_OOM;
            }
        }

        /* Main shift loop for unaligned shift */
        for (i = left->size + blocks + 1; i > blocks; i--)
        {
            tmp = 0;

            if (i - blocks - 1 < left->size)
                tmp |= left->data[i - blocks - 1] << bits;
            if (i - blocks - 2 < left->size)
                tmp |= left->data[i - blocks - 2] >> (BH_BIGINT_BITS - bits);

            to->data[i - 1] = tmp & BH_BIGINT_MASK;
        }

        /* Zero out shifted in blocks */
        for (; i > 0; i--)
            to->data[i - 1] = 0;

        /* Trim size to nearest block */
        i = left->size + blocks + 1;
        while (i && !to->data[i - 1]) i--;
    }
    else
    {
        /* Shift is block aligned */
        if (to->capacity < left->size + blocks)
        {
            if (bh_bigint_reserve(to, left->size + blocks))
            {
                to->error = 1;
                return BH_OOM;
            }
        }

        /* Main loop for aligned shift */
        for (i = left->size + blocks; i > blocks; i--)
            to->data[i - 1] = left->data[i - blocks - 1];

        /* Zero out shifted in blocks */
        for (; i > 0; i--)
            to->data[i - 1] = 0;

        /* Trim size to nearest block */
        i = left->size + blocks;
        while (i && !to->data[i - 1]) i--;
    }

    /* Update fields */
    to->size = i;
    to->type = left->type;

    return BH_OK;
}

int bh_bigint_rsh(bh_bigint_t *to,
                  bh_bigint_t *left,
                  bh_uint32_t shift)
{
    size_t i, bits, blocks;
    BH_BIGINT_TYPE tmp;

    /* Shortcut - one of the arguments has error flag set */
    if (left->error)
    {
        to->error = 1;
        return BH_ERROR;
    }

    /* Clear up result error flag */
    to->error = 0;

    /* Calculate distance in blocks and bits */
    blocks = shift / BH_BIGINT_BITS;
    bits = shift % BH_BIGINT_BITS;

    /* Shortcut - shift is bigger than value or value is 0 */
    if (left->type == 0 || left->size < blocks)
    {
        to->type = 0;
        to->size = 0;
        return BH_OK;
    }

    /* Check if shift is block aligned */
    if (bits)
    {
        /* Shift is not block aligned */
        if (to->capacity < left->size - blocks)
        {
            if (bh_bigint_reserve(to, left->size - blocks))
            {
                to->error = 1;
                return BH_OOM;
            }
        }

        /* Main loop for unaligned shift */
        for (i = 0; i < left->size - blocks; i++)
        {
            tmp = 0;

            if (i + blocks < left->size)
                tmp |= left->data[i + blocks] >> bits;
            if (i + blocks + 1 < left->size)
                tmp |= left->data[i + blocks + 1] << (BH_BIGINT_BITS - bits);

            tmp &= BH_BIGINT_MASK;
            to->data[i] = tmp;
        }
    }
    else
    {
        /* Shift is block aligned */
        if (to->capacity < left->size - blocks)
        {
            if (bh_bigint_reserve(to, left->size - blocks))
            {
                to->error = 1;
                return BH_OOM;
            }
        }

        /* Main loop for aligned shift */
        for (i = 0; i < left->size - blocks; i++)
            to->data[i] = left->data[i + blocks];
    }

    /* Trim remaining blocks */
    i = left->size - blocks;
    while (i && !to->data[i - 1]) i--;

    /* Update fields */
    to->size = i;
    to->type = left->type;

    if (!to->size)
        to->type = 0;

    return BH_OK;
}

int bh_bigint_or(bh_bigint_t *to,
                 bh_bigint_t *left,
                 bh_bigint_t *right)
{
    size_t i, size;
    BH_BIGINT_TYPE tmp;

    /* Shortcut - one of the arguments has error flag set */
    if (left->error || right->error)
    {
        to->error = 1;
        return BH_ERROR;
    }

    /* Clear up result error flag */
    to->error = 0;

    /* Calculate resulting size and reserve space */
    size = (left->size > right->size) ? (left->size) : (right->size);
    if (to->capacity < size)
    {
        if (bh_bigint_reserve(to, size))
        {
            to->error = 1;
            return BH_OOM;
        }
    }

    /* Apply OR for each block */
    for (i = 0; i < size; i++)
    {
        tmp = (i < left->size) ? (left->data[i]) : (0);
        tmp |= (i < right->size) ? (right->data[i]) : (0);
        to->data[i] = tmp;
    }

    /* Shrink size */
    while (size && !to->data[size - 1]) size--;

    /* Update fields */
    to->type = 1;
    to->size = size;

    if (!size)
        to->type = 0;

    return BH_OK;
}

int bh_bigint_and(bh_bigint_t *to,
                  bh_bigint_t *left,
                  bh_bigint_t *right)
{
    size_t i, size;
    BH_BIGINT_TYPE tmp;

    /* Shortcut - one of the arguments has error flag set */
    if (left->error || right->error)
    {
        to->error = 1;
        return BH_ERROR;
    }

    /* Clear up result error flag */
    to->error = 0;

    /* Calculate resulting size and reserve space */
    size = (left->size > right->size) ? (left->size) : (right->size);
    if (to->capacity < size)
    {
        if (bh_bigint_reserve(to, size))
        {
            to->error = 1;
            return BH_OOM;
        }
    }

    /* Apply AND for each block */
    for (i = 0; i < size; i++)
    {
        tmp = (i < left->size) ? (left->data[i]) : (0);
        tmp &= (i < right->size) ? (right->data[i]) : (0);
        to->data[i] = tmp;
    }

    /* Shrink size */
    while (size && !to->data[size - 1]) size--;

    /* Update fields */
    to->type = 1;
    to->size = size;

    if (!size)
        to->type = 0;

    return BH_OK;
}

int bh_bigint_xor(bh_bigint_t *to,
                  bh_bigint_t *left,
                  bh_bigint_t *right)
{
    size_t i, size;
    BH_BIGINT_TYPE tmp;

    /* Shortcut - one of the arguments has error flag set */
    if (left->error || right->error)
    {
        to->error = 1;
        return BH_ERROR;
    }

    /* Clear up result error flag */
    to->error = 0;

    /* Calculate resulting size and reserve space */
    size = (left->size > right->size) ? (left->size) : (right->size);
    if (to->capacity < size)
    {
        if (bh_bigint_reserve(to, size))
        {
            to->error = 1;
            return BH_OOM;
        }
    }

    /* Apply XOR for each block */
    for (i = 0; i < size; i++)
    {
        tmp = (i < left->size) ? (left->data[i]) : (0);
        tmp ^= (i < right->size) ? (right->data[i]) : (0);
        to->data[i] = tmp;
    }

    /* Shrink size */
    while (size && !to->data[size - 1]) size--;

    /* Update fields */
    to->type = 1;
    to->size = size;

    if (!size)
        to->type = 0;

    return BH_OK;
}

int bh_bigint_negate(bh_bigint_t *to,
                     bh_bigint_t *from)
{
    /* Shortcut - one of the arguments has error flag set */
    if (from->error)
    {
        to->error = 1;
        return BH_ERROR;
    }

    /* Clear up result error flag */
    to->error = 0;

    /* If to and from are not the same - copy data */
    if (to != from && bh_bigint_set(to, from))
    {
        to->error = 1;
        return BH_OOM;
    }

    /* Change the sign */
    to->type = 0 - to->type;

    return BH_OK;
}

int bh_bigint_equal(bh_bigint_t *left,
                    bh_bigint_t *right)
{
    /* Shortcut - one of the arguments have error flag set */
    if (left->error || right->error)
        return 0;

    /* Shortcut - check for sign */
    if (left->type - right->type)
        return left->type - right->type;

    /* Same sign - check contents */
    return bh_bigint_equal_mod(left, right);
}

int bh_bigint_equal_mod(bh_bigint_t *left,
                        bh_bigint_t *right)
{
    size_t i;

    /* Shortcut - one of the arguments have error flag set */
    if (left->error || right->error)
        return 0;

    /* Shortcut - check for length */
    if (left->size < right->size)
        return -1;
    else if (left->size > right->size)
        return 1;

    /* Equal length - compare unit by unit from the most significant */
    for (i = 0; i < left->size; i++)
    {
        size_t index = left->size - i - 1;

        if (left->data[index] < right->data[index])
            return -1;
        else if (left->data[index] > right->data[index])
            return 1;
    }

    /* Units are equal */
    return 0;
}

int bh_bigint_is_negative(bh_bigint_t *bigint)
{
    if (bigint->error)
        return 1;

    return bigint->type < 0;
}

int bh_bigint_is_zero(bh_bigint_t *bigint)
{
    if (bigint->error)
        return 1;

    return bigint->type == 0;
}

int bh_bigint_is_error(bh_bigint_t *bigint)
{
    return bigint->error;
}

size_t bh_bigint_log2(bh_bigint_t *bigint)
{
    size_t result;

    if (bigint->size == 0 || bigint->type == 0)
        return 0;

    result = bh_bigint_type_log2(bigint->data[bigint->size - 1]);
    return result + (bigint->size - 1) * BH_BIGINT_BITS;
}