X-Git-Url: https://git.cryptolib.org/?p=avr-crypto-lib.git;a=blobdiff_plain;f=bigint2%2Fbigint2.c;fp=bigint2%2Fbigint2.c;h=449070b3c9e117636683d8e0b899ab971da5cfd4;hp=0000000000000000000000000000000000000000;hb=cda2e9d578a68a57f3bd95c3ddbc5db78c7e3b36;hpb=55113fbb49edbc607a5ea5657be14e35296102c4 diff --git a/bigint2/bigint2.c b/bigint2/bigint2.c new file mode 100644 index 0000000..449070b --- /dev/null +++ b/bigint2/bigint2.c @@ -0,0 +1,956 @@ +/* + * bigint2.c + * + * Created on: 09.04.2014 + * Author: bg + */ + +#include +#include +#include +#include + +#define CHECKS 1 + +#define E_PARAM -1; +#define E_OOM -2; +#define E_VALUE -3; + + +#define MAX(a,b) ((a) > (b) ? (a) : (b)) +#define MIN(a,b) ((a) < (b) ? (a) : (b)) + +void *(*int_realloc)(void *ptr, size_t size); +void (*int_free)(void *ptr); + +/** + * \brief used to check if bigint is large enough + * Checks if the memory of a is large enough to hold min_size + * words, and if this is not the case tries to increase the allocated memory + * amount (conserving the memory content). + * If the allocated memory insufficient and the buffer could not be enlarged + * E_OOM is returned, otherwise 0 is returned. + */ +static +int check_size(bigint_t *a, bigint_length_t min_size) { + bigint_word_t *tmp; + if (a->allocated_W >= min_size) { + return 0; + } + tmp = int_realloc(a->wordv, min_size * sizeof(bigint_word_t)); + if (!tmp) { + return E_OOM; + } + a->wordv = tmp; + a->allocated_W = min_size; + return 0; +} + +int bigint_copy(bigint_t *dest, const bigint_t *a) { + int r; + if (dest == a) { + return 0; + } + r = check_size(dest, a->length_W); + if (r) { + return r; + } + dest->info = a->info; + dest->length_W = a->length_W; + memcpy(dest->wordv, a->wordv, a->length_W * sizeof(bigint_word_t)); + + return 0; +} + +int bigint_free(bigint_t *a) { + if(a->allocated_W) { + int_free(a->wordv); + } + memset(a, 0, sizeof(bigint_t)); + return 0; +} + +/** + * \brief dest = |a| + |b| + * Adds the bigints a and b and stores the result in dest. + * Signs are ignored. + */ +int bigint_add_u(bigint_t *dest, const bigint_t *a, const bigint_t *b) { + bigint_word_t t, c1, c2, c = 0; + bigint_length_t i, j; + int r; +#if CHECKS + if (!dest || !a || !b) { + return E_PARAM; + } +#endif +#if CHECKS + if ((r = check_size(dest, a->length_W))) { + return r; + } +#endif + j = MIN(a->length_W, b->length_W); + for (i = 0; i < j; ++i) { + t = a->wordv[i] + b->wordv[i]; + c1 = t < a->wordv[i]; + dest->wordv[i] = t + c; + c2 = dest->wordv[i] < t; + c = c1 | c2; + } + for (; i < a->length_W; ++i) { + t = a->wordv[i]; + dest->wordv[i] = t + c; + c = dest->wordv[i] < t; + } + dest->length_W = i; + return 0; +} + +/** UNSAFE!!! + * \brief dest = |a| + |b| + * Adds the bigints a and b and stores the result in dest. + * Signs are ignored. + */ +int bigint_add_auto_u(bigint_t *dest, const bigint_t *a, const bigint_t *b) { + bigint_word_t t, c1, c2, c = 0; + bigint_length_t i, j; + int r; +#if CHECKS + if (!dest || !a || !b) { + return E_PARAM; + } +#endif + if (a->length_W < b->length_W) { + const bigint_t *t; + t = a; + a = b; + b = t; + } +#if CHECKS + if ((r = check_size(dest, a->length_W + 1))) { + return r; + } +#endif + j = MIN(a->length_W, b->length_W); + for (i = 0; i < j; ++i) { + t = a->wordv[i] + b->wordv[i]; + c1 = t < a->wordv[i]; + dest->wordv[i] = t + c; + c2 = dest->wordv[i] < t; + c = c1 | c2; + } + for (; i < a->length_W; ++i) { + t = a->wordv[i]; + dest->wordv[i] = t + c; + c = dest->wordv[i] < t; + } + if (c) { + dest->wordv[i++] = c; + } + dest->length_W = i; + return 0; +} + + +/** + * \brief dest = ~a + */ +int bigint_invert(bigint_t *dest, const bigint_t *a) { + bigint_length_t i; + int r; +#if CHECKS + if ((r = check_size(dest, a->length_W))) { + return r; + } +#endif + i = a->length_W; + while(i--) { + dest->wordv[i] = ~a->wordv[i]; + } + dest->length_W = a->length_W; + return 0; +} + +/** + * \brief dest = a + 1 + */ +int bigint_add_one(bigint_t *dest, const bigint_t *a) { + bigint_t one = { + .wordv = (bigint_word_t*)"\x01", + .length_W = 1, + .allocated_W = 1, + .info = 0 + }; + return bigint_add_u(dest, a, &one); +} + +/** + * \brief dest = -a + */ +int bigint_negate(bigint_t *dest, const bigint_t *a) { + int r = 0; +#if CHECKS + if ((r = check_size(dest, a->length_W))) { + return r; + } +#endif + r |= bigint_invert(dest, a); + r |= bigint_add_one(dest, dest); + return r; +} + +/** + * \brief dest = |a| - |b| + * Subtracts b from a and stores the result in dest. + * Signs are ignored + */ +int bigint_sub_u(bigint_t *dest, const bigint_t *a, const bigint_t *b) { + bigint_length_t i, j; + bigint_word_t t, c1, c2, c = 0; + int r; +#if CHECKS + if (!dest || !a || !b) { + return E_PARAM; + } +#endif +#if CHECKS + if ((r = check_size(dest, MAX(a->length_W, b->length_W)))) { + return r; + } + +#endif + j = MIN(a->length_W, b->length_W); + for (i = 0; i < j; ++i) { + t = a->wordv[i] - b->wordv[i]; + c1 = t > a->wordv[i]; + dest->wordv[i] = t - c; + c2 = dest->wordv[i] > t; + c = c1 | c2; + } + for (; i < a->length_W; ++i) { + t = a->wordv[i]; + dest->wordv[i] = t - c; + c = dest->wordv[i] > t; + } + dest->length_W = a->length_W; + return 0; +} + +/** + * \brief a <<= 1 + */ +int bigint_shiftleft_words(bigint_t *dest, const bigint_t *a, bigint_length_t s) { +#if CHECKS + if (!a) { + return E_PARAM; + } +#endif + if (s == 0) { + bigint_copy(dest, a); + return 0; + } + int r; + if ((r = check_size(dest, a->length_W + s))) { + return r; + } + memmove(&dest->wordv[s], &a->wordv[0], a->length_W * sizeof(bigint_word_t)); + memset(&dest->wordv[0], 0, s * sizeof(bigint_word_t)); + dest->length_W = a->length_W + s; + return 0; +} + + +/** + * \brief a <<= 1 + */ +int bigint_shiftleft_1bit(bigint_t *a) { + uint8_t c1 = 0, c2; + bigint_word_t t; + bigint_length_t i; +#if CHECKS + if (!a) { + return E_PARAM; + } +#endif + + for(i = 0; i < a->length_W; ++i) { + t = a->wordv[i]; + c2 = t >> (BIGINT_WORD_SIZE - 1); + t <<= 1; + t |= c1; + a->wordv[i] = t; + c1 = c2; + } + + return 0; +} + +/** + * \brief a <<= s + */ +static +int bigint_shiftleft_small(bigint_t *dest, const bigint_t *a, uint_fast8_t s) { + bigint_wordplus_t t = 0; + bigint_length_t i, l; +#if CHECKS + if (!a) { + return E_PARAM; + } +#endif + l = bigint_get_first_set_bit(a) + BIGINT_WORD_SIZE; +#if CHECKS + int r; + if ((r = check_size(dest, (l + s ) / BIGINT_WORD_SIZE))) { + return r; + } + +#endif + dest->length_W = (l + s ) / BIGINT_WORD_SIZE; + l /= BIGINT_WORD_SIZE; + for(i = 0; i < l; ++i) { + t |= (bigint_wordplus_t)a->wordv[i] << s; + dest->wordv[i] = t; + t >>= BIGINT_WORD_SIZE; + } + if (t) { + dest->wordv[i] = t; + } + return 0; +} + +/** + * \brief dest = a << s + */ +int bigint_shiftleft(bigint_t *dest, const bigint_t *a, bigint_length_t s) { + int r; + if((r = bigint_shiftleft_small(dest, a, s % BIGINT_WORD_SIZE))) { + return r; + } + if ((r = bigint_shiftleft_words(dest, dest, s / BIGINT_WORD_SIZE))) { + return r; + } + return 0; +} + +/** + * \brief a >>= 1 + */ +int bigint_shiftright_1bit(bigint_t *a) { + uint8_t c1 = 0, c2; + bigint_word_t t; + bigint_length_t i; +#if CHECKS + if (!a) { + return E_PARAM; + } +#endif + + for(i = a->length_W; i != 0; --i) { + t = a->wordv[i - 1]; + c2 = t & 1; + t >>= 1; + t |= c1 << (BIGINT_WORD_SIZE - 1); + a->wordv[i - 1] = t; + c1 = c2; + } + + return 0; +} + +/** + * \brief dest = a ** 2 + */ +int bigint_square(bigint_t *dest, const bigint_t *a) { + bigint_word_t c1, c2; + bigint_wordplus_t uv; + bigint_word_t q; + bigint_length_t i, j; +#if CHECKS + int r; + if (!dest || !a) { + return E_PARAM; + } + if ((r = check_size(dest, a->length_W * 2))) { + return r; + } +#endif + if (dest == a) { + bigint_t t = {NULL, 0, 0, 0}; + bigint_copy(&t, a); + r = bigint_square(dest, &t); + bigint_free(&t); + return r; + } + memset(dest->wordv, 0, 2 * a->length_W * sizeof(bigint_word_t)); + for(i = 0; i < a->length_W; ++i) { + uv = (bigint_wordplus_t)dest->wordv[2 * i] + + (bigint_wordplus_t)a->wordv[i] + * (bigint_wordplus_t)a->wordv[i]; + dest->wordv[2 * i] = uv; + c1 = uv >> BIGINT_WORD_SIZE; + c2 = 0; + for (j = i + 1; j < a->length_W; ++j) { + uv = (bigint_wordplus_t)a->wordv[i] + * (bigint_wordplus_t)a->wordv[j]; + q = uv >> (2 * BIGINT_WORD_SIZE - 1); + uv <<= 1; + uv += dest->wordv[i + j]; + q += (uv < dest->wordv[i + j]); /* this might be dangerous! XXX */ + uv += c1; + q += (uv < c1); /* this might be dangerous! XXX */ + dest->wordv[i + j] = uv; + c1 = c2 + (uv >> BIGINT_WORD_SIZE); + c2 = q + (c1 < c2); /* this might be dangerous! XXX */ + } + dest->wordv[i + a->length_W] += c1; + dest->wordv[i + a->length_W + 1] = c2 + (dest->wordv[i + a->length_W] < c1); /* this might be dangerous! XXX */ + } + dest->length_W = a->length_W * 2; + return 0; +} + + +/** + * \brief dest = |a * b| + * unsigned multiply a bigint (a) by a word (b) + */ +int bigint_mul_word(bigint_t *dest, const bigint_t *a, const bigint_word_t b) { + bigint_wordplus_t c1 = 0; + bigint_length_t i; +#if CHECKS + int r; + if (!dest || !a || !b) { + return E_PARAM; + } + if ((r = check_size(dest, a->length_W + 1))) { + return r; + } +#endif + for(i = 0; i < a->length_W; ++i) { + c1 += (bigint_wordplus_t)b * (bigint_wordplus_t)a->wordv[i]; + dest->wordv[i] = c1; + c1 >>= BIGINT_WORD_SIZE; + } + dest->wordv[i++] = c1; + dest->length_W = i; + BIGINT_SET_POS(dest); + return 0; +} + +/** + * \brief dest = a * b + */ +int bigint_mul_schoolbook(bigint_t *dest, const bigint_t *a, const bigint_t *b) { + bigint_wordplus_t v; + bigint_word_t c; + bigint_length_t i, j; + int r; +#if CHECKS + if (!dest || !a || !b) { + return E_PARAM; + } + if ((r = check_size(dest, a->length_W + b->length_W))) { + return r; + } +#endif + if (dest == a) { + bigint_t t = {NULL, 0, 0, 0}; + bigint_copy(&t, a); + r = bigint_mul_schoolbook(dest, &t, b); + bigint_free(&t); + return r; + } + if (dest == b) { + bigint_t t = {NULL, 0, 0, 0}; + bigint_copy(&t, b); + r = bigint_mul_schoolbook(dest, a, &t); + bigint_free(&t); + return r; + } + memset(dest->wordv, 0, (a->length_W + b->length_W) * sizeof(bigint_word_t)); + for(i = 0; i < b->length_W; ++i) { + c = 0; + for(j = 0; j < a->length_W; ++j) { + v = (bigint_wordplus_t)a->wordv[j] + * (bigint_wordplus_t)b->wordv[i]; + v += (bigint_wordplus_t)dest->wordv[i + j]; + v += (bigint_wordplus_t)c; + dest->wordv[i + j] = v; + c = v >> BIGINT_WORD_SIZE; + } + dest->wordv[i + j] = c; + } + + dest->length_W = a->length_W + b->length_W; + dest->info &= ~BIGINT_SIGN_MASK; + dest->info |= (a->info ^ b->info) & BIGINT_SIGN_MASK; + return 0; +} + +/* + * UNSAFE!!! + */ +int8_t bigint_cmp_u(const bigint_t *a, const bigint_t *b) { + int8_t r = 1; + bigint_length_t i; + if (a->length_W == 0 && b->length_W == 0) { + return 0; + } + if (b->length_W == 0) { + return 1; + } + if (a->length_W == 0) { + return -1; + } + if (a->length_W < b->length_W) { + const bigint_t *t; + t = a; + a = b; + b = t; + r = -1; + } + for (i = a->length_W - 1; i > b->length_W - 1; --i) { + if (a->wordv[i]) { + return r; + } + } + ++i; + do { + --i; + if (a->wordv[i] != b->wordv[i]) { + return a->wordv[i] > b->wordv[i] ? r : -r; + } + } while (i); + return 0; +} + +int8_t bigint_cmp_s(const bigint_t *a, const bigint_t *b) { + if ( bigint_get_first_set_bit(a) == (bigint_length_t)-1 && + bigint_get_first_set_bit(b) == (bigint_length_t)-1 ) { + return 0; + } + if ((a->info & BIGINT_SIGN_MASK) ^ (b->info & BIGINT_SIGN_MASK)) { + return (a->info & BIGINT_SIGN_MASK) ? -1 : 1; + } else { + int r; + r = bigint_cmp_u(a, b); + return (a->info & BIGINT_SIGN_MASK) ? -r : r; + } + return 0; +} + +/* + * UNSAFE!!! + * a <=> b * (B ** s) + */ +int8_t bigint_cmp_scale(const bigint_t *a, const bigint_t *b, bigint_length_t s) { + bigint_length_t i; + if (s == 0) { + return bigint_cmp_u(a, b); + } + if (a->length_W == 0 && b->length_W == 0) { + return 0; + } + if (b->length_W == 0) { + return 1; + } + if (a->length_W == 0) { + return -1; + } + if (s > a->length_W) { + return -1; + } + for (i = a->length_W - 1; i > b->length_W + s - 1; --i) { + if (a->wordv[i]) { + return 1; + } + } + for (; i > s - 1; --i) { + if (a->wordv[i] != b->wordv[i + s]){ + return a->wordv[i] > b->wordv[i + s] ? 1 : -1; + } + } + ++i; + do { + --i; + if (a->wordv[i]) { + return 1; + } + } while (i); + return 0; +} + +/** + * XXXXXXXXXXXX + * \brief dest = |a| - |b| * B ** s + * Subtracts b from a and stores the result in dest. + * Signs are ignored + */ +int bigint_sub_scale(bigint_t *dest, const bigint_t *a, const bigint_t *b, bigint_length_t s) { + bigint_length_t i, j; + bigint_word_t t, c1, c2, c = 0; + int r; +#if CHECKS + if (!dest || !a || !b) { + return E_PARAM; + } +#endif +#if CHECKS + if ((r = check_size(dest, MAX(a->length_W, b->length_W)))) { + return r; + } + +#endif + j = MIN(a->length_W, b->length_W); + for (i = 0; i < j; ++i) { + t = a->wordv[i + s] - b->wordv[i]; + c1 = t > a->wordv[i + s]; + dest->wordv[i + s] = t - c; + c2 = dest->wordv[i + s] > t; + c = c1 | c2; + } + for (; i < a->length_W; ++i) { + t = a->wordv[i + s]; + dest->wordv[i + s] = t - c; + c = dest->wordv[i + s] > t; + } + dest->length_W = a->length_W; + return 0; +} + +/* + * UNSAFE!!! + */ +int bigint_adjust_length(bigint_t *a) { +#if CHECKS + if (!a) { + return E_PARAM; + } +#endif + while (a->length_W) { + if (a->wordv[a->length_W - 1]) { + return 0; + } + a->length_W--; + } + return 0; +} + +bigint_length_t bigint_get_first_set_bit(const bigint_t *a) { + bigint_length_t r; + bigint_word_t t; + if (!a) { + return (bigint_length_t)-1; + } + if (a->length_W == 0) { + return (bigint_length_t)-1; + } + r = a->length_W - 1; + while (r && a->wordv[r] == 0) { + --r; + } + t = a->wordv[r]; + if (!t) { + return (bigint_length_t)-1; + } + r *= BIGINT_WORD_SIZE; + t >>= 1; + while (t) { + t >>= 1; + ++r; + } + return r; +} + +/* + * UNSAFE!!! + * a = q * b + r + */ +int bigint_divide(bigint_t *q, bigint_t *r, const bigint_t *a, const bigint_t *b) { + bigint_t a_ = {NULL, 0, 0, 0}, x_ = {NULL, 0, 0, 0}; + bigint_length_t i, la, lb; + int ret; +#if CHECKS + if (!a || !b || (!q && !r)) { + return E_PARAM; + } +#endif + la = bigint_get_first_set_bit(a); + lb = bigint_get_first_set_bit(b); + if (lb == (bigint_length_t)-1) { + return E_VALUE; + } + if (la == (bigint_length_t)-1) { + if (q) { + q->length_W = 0; + } + if (r) { + r->length_W = 0; + } + return 0; + } + if (la < lb) { + if (q) { + q->length_W = 0; + } + if (r) { + bigint_copy(r, a); + } + return 0; + } + i = la - lb; + if (q) { + if ((ret = check_size(q, (i + BIGINT_WORD_SIZE - 1) / BIGINT_WORD_SIZE))) { + return ret; + } + memset(q->wordv, 0, q->allocated_W * sizeof(bigint_word_t)); + } + if (r) { + if ((ret = check_size(q, (lb + BIGINT_WORD_SIZE - 1) / BIGINT_WORD_SIZE))) { + return ret; + } + } + if ((ret = bigint_copy(&a_, a))) { + return ret; + } + if ((ret = bigint_shiftleft(&x_, b, i))) { + bigint_free(&a_); + return ret; + } +#if 0 + printf("DBG: x' = "); + bigint_print_hex(&x_); + printf("; b = "); + bigint_print_hex(b); + printf("; la = %d; lb = %d; i = %d\n", la, lb, i); +#endif + do { + if (bigint_cmp_u(&a_, &x_) >= 0) { + bigint_sub_u(&a_, &a_, &x_); + if (q) { + q->wordv[i / BIGINT_WORD_SIZE] |= 1 << (i % BIGINT_WORD_SIZE); + } + } + bigint_shiftright_1bit(&x_); + } while (i--); + if (r) { + bigint_copy(r, &a_); + } + bigint_free(&x_); + bigint_free(&a_); + return 0; +} + +/** + * UNSAFE!!! + */ +int bigint_sub_s(bigint_t *dest, const bigint_t *a, const bigint_t *b) { + int8_t s; + int r; + if (a->length_W == 0) { + bigint_copy(dest, b); + dest->info ^= BIGINT_SIGN_MASK; + return 0; + } + if ((a->info ^ b->info) & BIGINT_SIGN_MASK) { + /* different signs */ + if ((r = bigint_add_auto_u(dest, a, b))) { + return r; + } + dest->info = a->info; + } else { + s = bigint_cmp_u(a, b); + if (s >= 0) { + if (( r = bigint_sub_u(dest, a, b))) { + return r; + } + dest->info = a->info; + } else { + if (( r = bigint_sub_u(dest, b, a))) { + return r; + } + dest->info = (~a->info) & BIGINT_SIGN_MASK; + } + } + return 0; +} + +/** + * UNSAFE!!! + */ +int bigint_add_s(bigint_t *dest, const bigint_t *a, const bigint_t *b) { + int8_t s; + int r; + if ((a->info ^ b->info) & BIGINT_SIGN_MASK) { + /* different signs */ + s = bigint_cmp_u(a, b); + if (s >= 0) { + if (( r = bigint_sub_u(dest, a, b))) { + return r; + } + dest->info = a->info; + } else { + if (( r = bigint_sub_u(dest, b, a))) { + return r; + } + dest->info = (~a->info) & BIGINT_SIGN_MASK; + } + } else { + if ((r = bigint_add_auto_u(dest, a, b))) { + return r; + } + dest->info = a->info; + } + return 0; +} + +int8_t bigint_is_even(const bigint_t *a) { + if (!a) { + return E_VALUE; + } + if (a->length_W == 0 || (a->wordv[0] & 1) == 0) { + return 1; + } + return 0; +} + +int8_t bigint_is_odd(const bigint_t *a) { + if (!a) { + return E_VALUE; + } + if (a->length_W > 0 && (a->wordv[0] & 1) == 1) { + return 1; + } + return 0; +} + +/** + * UNSAFE!!! + * (a, b) -> (x, y, v) + * v = gcd(a,b) + * x * a + y * b = v + */ +int bigint_gcdext(bigint_t *gcd, bigint_t *x, bigint_t *y, const bigint_t *a, const bigint_t *b) { + bigint_length_t g = 0; + bigint_t u = {NULL, 0, 0, 0}, v = {NULL, 0, 0, 0}; + bigint_t x_ = {NULL, 0, 0, 0}, y_ = {NULL, 0, 0, 0}; + bigint_t A = {NULL, 0, 0, 0}, B = {NULL, 0, 0, 0}; + bigint_t C = {NULL, 0, 0, 0}, D = {NULL, 0, 0, 0}; + int r; + if ((r = bigint_copy(&x_, a))) { + return r; + } + if ((r = bigint_copy(&y_, b))) { + bigint_free(&x_); + return r; + } + bigint_adjust_length(&x_); + bigint_adjust_length(&y_); + if (x_.length_W == 0 || y_.length_W == 0) { + bigint_free(&y_); + bigint_free(&x_); + return E_VALUE; + } + while (((x_.wordv[0] | y_.wordv[0]) & 1) == 0) { + ++g; + bigint_shiftright_1bit(&x_); + bigint_shiftright_1bit(&y_); + } + if ((r = check_size(&A, 1 + (bigint_get_first_set_bit(&y_) + BIGINT_WORD_SIZE) / BIGINT_WORD_SIZE))) { + bigint_free(&y_); + bigint_free(&x_); + return r; + } + if ((r = check_size(&C, 1 + (bigint_get_first_set_bit(&y_) + BIGINT_WORD_SIZE) / BIGINT_WORD_SIZE))) { + bigint_free(&A); + bigint_free(&y_); + bigint_free(&x_); + return r; + } + if ((r = check_size(&B, 1 + (bigint_get_first_set_bit(&x_) + BIGINT_WORD_SIZE) / BIGINT_WORD_SIZE))) { + bigint_free(&C); + bigint_free(&A); + bigint_free(&y_); + bigint_free(&x_); + return r; + } + if ((r = check_size(&D, 1 + (bigint_get_first_set_bit(&x_) + BIGINT_WORD_SIZE) / BIGINT_WORD_SIZE))) { + bigint_free(&B); + bigint_free(&C); + bigint_free(&A); + bigint_free(&y_); + bigint_free(&x_); + return r; + } + if ((r = bigint_copy(&u, &x_))) { + bigint_free(&D); + bigint_free(&B); + bigint_free(&C); + bigint_free(&A); + bigint_free(&y_); + bigint_free(&x_); + return r; + } + if ((r = bigint_copy(&v, &y_))) { + bigint_free(&u); + bigint_free(&D); + bigint_free(&B); + bigint_free(&C); + bigint_free(&A); + bigint_free(&y_); + bigint_free(&x_); + return r; + } + A.wordv[0] = D.wordv[0] = 1; + A.length_W = D.length_W = 1; + C.length_W = B.length_W = 0; + + do { + while ((u.wordv[0] & 1) == 0) { + bigint_shiftright_1bit(&u); + if (bigint_is_odd(&A) || bigint_is_odd(&B)) { + bigint_add_s(&A, &A, &y_); + bigint_sub_s(&B, &B, &x_); + } + bigint_shiftright_1bit(&A); + bigint_shiftright_1bit(&B); + } + while ((v.wordv[0] & 1) == 0) { + bigint_shiftright_1bit(&v); + if (bigint_is_odd(&C) || bigint_is_odd(&D)) { + bigint_add_s(&C, &C, &y_); + bigint_sub_s(&D, &D, &x_); + } + bigint_shiftright_1bit(&C); + bigint_shiftright_1bit(&D); + } + if (bigint_cmp_s(&u, &v) >= 0) { + bigint_sub_s(&u, &u, &v); + bigint_sub_s(&A, &A, &C); + bigint_sub_s(&B, &B, &D); + } else { + bigint_sub_s(&v, &v, &u); + bigint_sub_s(&C, &C, &A); + bigint_sub_s(&D, &D, &B); + } + bigint_adjust_length(&u); + } while (u.length_W != 0); + if (gcd) { + bigint_shiftleft(gcd, &v, g); + } + if (x) { + bigint_copy(x, &C); + } + if (y) { + bigint_copy(y, &D); + } + bigint_free(&v); + bigint_free(&u); + bigint_free(&D); + bigint_free(&B); + bigint_free(&C); + bigint_free(&A); + bigint_free(&y_); + bigint_free(&x_); + return 0; +}