static unsigned int BN_STACK_pop(BN_STACK *st)
{
    return st->indexes[--(st->depth)];
}
['BIGNUM *BN_mod_sqrt(BIGNUM *in, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)\n{\n    BIGNUM *ret = in;\n    int err = 1;\n    int r;\n    BIGNUM *A, *b, *q, *t, *x, *y;\n    int e, i, j;\n    if (!BN_is_odd(p) || BN_abs_is_word(p, 1)) {\n        if (BN_abs_is_word(p, 2)) {\n            if (ret == NULL)\n                ret = BN_new();\n            if (ret == NULL)\n                goto end;\n            if (!BN_set_word(ret, BN_is_bit_set(a, 0))) {\n                if (ret != in)\n                    BN_free(ret);\n                return NULL;\n            }\n            bn_check_top(ret);\n            return ret;\n        }\n        BNerr(BN_F_BN_MOD_SQRT, BN_R_P_IS_NOT_PRIME);\n        return NULL;\n    }\n    if (BN_is_zero(a) || BN_is_one(a)) {\n        if (ret == NULL)\n            ret = BN_new();\n        if (ret == NULL)\n            goto end;\n        if (!BN_set_word(ret, BN_is_one(a))) {\n            if (ret != in)\n                BN_free(ret);\n            return NULL;\n        }\n        bn_check_top(ret);\n        return ret;\n    }\n    BN_CTX_start(ctx);\n    A = BN_CTX_get(ctx);\n    b = BN_CTX_get(ctx);\n    q = BN_CTX_get(ctx);\n    t = BN_CTX_get(ctx);\n    x = BN_CTX_get(ctx);\n    y = BN_CTX_get(ctx);\n    if (y == NULL)\n        goto end;\n    if (ret == NULL)\n        ret = BN_new();\n    if (ret == NULL)\n        goto end;\n    if (!BN_nnmod(A, a, p, ctx))\n        goto end;\n    e = 1;\n    while (!BN_is_bit_set(p, e))\n        e++;\n    if (e == 1) {\n        if (!BN_rshift(q, p, 2))\n            goto end;\n        q->neg = 0;\n        if (!BN_add_word(q, 1))\n            goto end;\n        if (!BN_mod_exp(ret, A, q, p, ctx))\n            goto end;\n        err = 0;\n        goto vrfy;\n    }\n    if (e == 2) {\n        if (!BN_mod_lshift1_quick(t, A, p))\n            goto end;\n        if (!BN_rshift(q, p, 3))\n            goto end;\n        q->neg = 0;\n        if (!BN_mod_exp(b, t, q, p, ctx))\n            goto end;\n        if (!BN_mod_sqr(y, b, p, ctx))\n            goto end;\n        if (!BN_mod_mul(t, t, y, p, ctx))\n            goto end;\n        if (!BN_sub_word(t, 1))\n            goto end;\n        if (!BN_mod_mul(x, A, b, p, ctx))\n            goto end;\n        if (!BN_mod_mul(x, x, t, p, ctx))\n            goto end;\n        if (!BN_copy(ret, x))\n            goto end;\n        err = 0;\n        goto vrfy;\n    }\n    if (!BN_copy(q, p))\n        goto end;\n    q->neg = 0;\n    i = 2;\n    do {\n        if (i < 22) {\n            if (!BN_set_word(y, i))\n                goto end;\n        } else {\n            if (!BN_priv_rand(y, BN_num_bits(p), 0, 0))\n                goto end;\n            if (BN_ucmp(y, p) >= 0) {\n                if (!(p->neg ? BN_add : BN_sub) (y, y, p))\n                    goto end;\n            }\n            if (BN_is_zero(y))\n                if (!BN_set_word(y, i))\n                    goto end;\n        }\n        r = BN_kronecker(y, q, ctx);\n        if (r < -1)\n            goto end;\n        if (r == 0) {\n            BNerr(BN_F_BN_MOD_SQRT, BN_R_P_IS_NOT_PRIME);\n            goto end;\n        }\n    }\n    while (r == 1 && ++i < 82);\n    if (r != -1) {\n        BNerr(BN_F_BN_MOD_SQRT, BN_R_TOO_MANY_ITERATIONS);\n        goto end;\n    }\n    if (!BN_rshift(q, q, e))\n        goto end;\n    if (!BN_mod_exp(y, y, q, p, ctx))\n        goto end;\n    if (BN_is_one(y)) {\n        BNerr(BN_F_BN_MOD_SQRT, BN_R_P_IS_NOT_PRIME);\n        goto end;\n    }\n    if (!BN_rshift1(t, q))\n        goto end;\n    if (BN_is_zero(t)) {\n        if (!BN_nnmod(t, A, p, ctx))\n            goto end;\n        if (BN_is_zero(t)) {\n            BN_zero(ret);\n            err = 0;\n            goto end;\n        } else if (!BN_one(x))\n            goto end;\n    } else {\n        if (!BN_mod_exp(x, A, t, p, ctx))\n            goto end;\n        if (BN_is_zero(x)) {\n            BN_zero(ret);\n            err = 0;\n            goto end;\n        }\n    }\n    if (!BN_mod_sqr(b, x, p, ctx))\n        goto end;\n    if (!BN_mod_mul(b, b, A, p, ctx))\n        goto end;\n    if (!BN_mod_mul(x, x, A, p, ctx))\n        goto end;\n    while (1) {\n        if (BN_is_one(b)) {\n            if (!BN_copy(ret, x))\n                goto end;\n            err = 0;\n            goto vrfy;\n        }\n        i = 1;\n        if (!BN_mod_sqr(t, b, p, ctx))\n            goto end;\n        while (!BN_is_one(t)) {\n            i++;\n            if (i == e) {\n                BNerr(BN_F_BN_MOD_SQRT, BN_R_NOT_A_SQUARE);\n                goto end;\n            }\n            if (!BN_mod_mul(t, t, t, p, ctx))\n                goto end;\n        }\n        if (!BN_copy(t, y))\n            goto end;\n        for (j = e - i - 1; j > 0; j--) {\n            if (!BN_mod_sqr(t, t, p, ctx))\n                goto end;\n        }\n        if (!BN_mod_mul(y, t, t, p, ctx))\n            goto end;\n        if (!BN_mod_mul(x, x, t, p, ctx))\n            goto end;\n        if (!BN_mod_mul(b, b, y, p, ctx))\n            goto end;\n        e = i;\n    }\n vrfy:\n    if (!err) {\n        if (!BN_mod_sqr(x, ret, p, ctx))\n            err = 1;\n        if (!err && 0 != BN_cmp(x, A)) {\n            BNerr(BN_F_BN_MOD_SQRT, BN_R_NOT_A_SQUARE);\n            err = 1;\n        }\n    }\n end:\n    if (err) {\n        if (ret != in)\n            BN_clear_free(ret);\n        ret = NULL;\n    }\n    BN_CTX_end(ctx);\n    bn_check_top(ret);\n    return ret;\n}', 'void BN_CTX_start(BN_CTX *ctx)\n{\n    CTXDBG("ENTER BN_CTX_start()", ctx);\n    if (ctx->err_stack || ctx->too_many)\n        ctx->err_stack++;\n    else if (!BN_STACK_push(&ctx->stack, ctx->used)) {\n        BNerr(BN_F_BN_CTX_START, BN_R_TOO_MANY_TEMPORARY_VARIABLES);\n        ctx->err_stack++;\n    }\n    CTXDBG("LEAVE BN_CTX_start()", ctx);\n}', 'BIGNUM *BN_CTX_get(BN_CTX *ctx)\n{\n    BIGNUM *ret;\n    CTXDBG("ENTER BN_CTX_get()", ctx);\n    if (ctx->err_stack || ctx->too_many)\n        return NULL;\n    if ((ret = BN_POOL_get(&ctx->pool, ctx->flags)) == NULL) {\n        ctx->too_many = 1;\n        BNerr(BN_F_BN_CTX_GET, BN_R_TOO_MANY_TEMPORARY_VARIABLES);\n        return NULL;\n    }\n    BN_zero(ret);\n    ret->flags &= (~BN_FLG_CONSTTIME);\n    ctx->used++;\n    CTXDBG("LEAVE BN_CTX_get()", ctx);\n    return ret;\n}', 'int BN_nnmod(BIGNUM *r, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx)\n{\n    if (!(BN_mod(r, m, d, ctx)))\n        return 0;\n    if (!r->neg)\n        return 1;\n    return (d->neg ? BN_sub : BN_add) (r, r, d);\n}', 'int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,\n           BN_CTX *ctx)\n{\n    int ret;\n    if (BN_is_zero(divisor)) {\n        BNerr(BN_F_BN_DIV, BN_R_DIV_BY_ZERO);\n        return 0;\n    }\n    if (divisor->d[divisor->top - 1] == 0) {\n        BNerr(BN_F_BN_DIV, BN_R_NOT_INITIALIZED);\n        return 0;\n    }\n    ret = bn_div_fixed_top(dv, rm, num, divisor, ctx);\n    if (ret) {\n        if (dv != NULL)\n            bn_correct_top(dv);\n        if (rm != NULL)\n            bn_correct_top(rm);\n    }\n    return ret;\n}', 'int BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,\n               BN_CTX *ctx)\n{\n    int ret;\n    bn_check_top(a);\n    bn_check_top(p);\n    bn_check_top(m);\n#define MONT_MUL_MOD\n#define MONT_EXP_WORD\n#define RECP_MUL_MOD\n#ifdef MONT_MUL_MOD\n    if (BN_is_odd(m)) {\n# ifdef MONT_EXP_WORD\n        if (a->top == 1 && !a->neg\n            && (BN_get_flags(p, BN_FLG_CONSTTIME) == 0)\n            && (BN_get_flags(a, BN_FLG_CONSTTIME) == 0)\n            && (BN_get_flags(m, BN_FLG_CONSTTIME) == 0)) {\n            BN_ULONG A = a->d[0];\n            ret = BN_mod_exp_mont_word(r, A, p, m, ctx, NULL);\n        } else\n# endif\n            ret = BN_mod_exp_mont(r, a, p, m, ctx, NULL);\n    } else\n#endif\n#ifdef RECP_MUL_MOD\n    {\n        ret = BN_mod_exp_recp(r, a, p, m, ctx);\n    }\n#else\n    {\n        ret = BN_mod_exp_simple(r, a, p, m, ctx);\n    }\n#endif\n    bn_check_top(r);\n    return ret;\n}', 'int BN_mod_exp_mont_word(BIGNUM *rr, BN_ULONG a, const BIGNUM *p,\n                         const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)\n{\n    BN_MONT_CTX *mont = NULL;\n    int b, bits, ret = 0;\n    int r_is_one;\n    BN_ULONG w, next_w;\n    BIGNUM *r, *t;\n    BIGNUM *swap_tmp;\n#define BN_MOD_MUL_WORD(r, w, m) \\\n                (BN_mul_word(r, (w)) && \\\n                (   \\\n                        (BN_mod(t, r, m, ctx) && (swap_tmp = r, r = t, t = swap_tmp, 1))))\n#define BN_TO_MONTGOMERY_WORD(r, w, mont) \\\n                (BN_set_word(r, (w)) && BN_to_montgomery(r, r, (mont), ctx))\n    if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0\n            || BN_get_flags(m, BN_FLG_CONSTTIME) != 0) {\n        BNerr(BN_F_BN_MOD_EXP_MONT_WORD, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);\n        return 0;\n    }\n    bn_check_top(p);\n    bn_check_top(m);\n    if (!BN_is_odd(m)) {\n        BNerr(BN_F_BN_MOD_EXP_MONT_WORD, BN_R_CALLED_WITH_EVEN_MODULUS);\n        return 0;\n    }\n    if (m->top == 1)\n        a %= m->d[0];\n    bits = BN_num_bits(p);\n    if (bits == 0) {\n        if (BN_abs_is_word(m, 1)) {\n            ret = 1;\n            BN_zero(rr);\n        } else {\n            ret = BN_one(rr);\n        }\n        return ret;\n    }\n    if (a == 0) {\n        BN_zero(rr);\n        ret = 1;\n        return ret;\n    }\n    BN_CTX_start(ctx);\n    r = BN_CTX_get(ctx);\n    t = BN_CTX_get(ctx);\n    if (t == NULL)\n        goto err;\n    if (in_mont != NULL)\n        mont = in_mont;\n    else {\n        if ((mont = BN_MONT_CTX_new()) == NULL)\n            goto err;\n        if (!BN_MONT_CTX_set(mont, m, ctx))\n            goto err;\n    }\n    r_is_one = 1;\n    w = a;\n    for (b = bits - 2; b >= 0; b--) {\n        next_w = w * w;\n        if ((next_w / w) != w) {\n            if (r_is_one) {\n                if (!BN_TO_MONTGOMERY_WORD(r, w, mont))\n                    goto err;\n                r_is_one = 0;\n            } else {\n                if (!BN_MOD_MUL_WORD(r, w, m))\n                    goto err;\n            }\n            next_w = 1;\n        }\n        w = next_w;\n        if (!r_is_one) {\n            if (!BN_mod_mul_montgomery(r, r, r, mont, ctx))\n                goto err;\n        }\n        if (BN_is_bit_set(p, b)) {\n            next_w = w * a;\n            if ((next_w / a) != w) {\n                if (r_is_one) {\n                    if (!BN_TO_MONTGOMERY_WORD(r, w, mont))\n                        goto err;\n                    r_is_one = 0;\n                } else {\n                    if (!BN_MOD_MUL_WORD(r, w, m))\n                        goto err;\n                }\n                next_w = a;\n            }\n            w = next_w;\n        }\n    }\n    if (w != 1) {\n        if (r_is_one) {\n            if (!BN_TO_MONTGOMERY_WORD(r, w, mont))\n                goto err;\n            r_is_one = 0;\n        } else {\n            if (!BN_MOD_MUL_WORD(r, w, m))\n                goto err;\n        }\n    }\n    if (r_is_one) {\n        if (!BN_one(rr))\n            goto err;\n    } else {\n        if (!BN_from_montgomery(rr, r, mont, ctx))\n            goto err;\n    }\n    ret = 1;\n err:\n    if (in_mont == NULL)\n        BN_MONT_CTX_free(mont);\n    BN_CTX_end(ctx);\n    bn_check_top(rr);\n    return ret;\n}', 'int BN_mod_sqr(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx)\n{\n    if (!BN_sqr(r, a, ctx))\n        return 0;\n    return BN_mod(r, r, m, ctx);\n}', 'int BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)\n{\n    int ret = bn_sqr_fixed_top(r, a, ctx);\n    bn_correct_top(r);\n    bn_check_top(r);\n    return ret;\n}', 'int bn_sqr_fixed_top(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)\n{\n    int max, al;\n    int ret = 0;\n    BIGNUM *tmp, *rr;\n    bn_check_top(a);\n    al = a->top;\n    if (al <= 0) {\n        r->top = 0;\n        r->neg = 0;\n        return 1;\n    }\n    BN_CTX_start(ctx);\n    rr = (a != r) ? r : BN_CTX_get(ctx);\n    tmp = BN_CTX_get(ctx);\n    if (rr == NULL || tmp == NULL)\n        goto err;\n    max = 2 * al;\n    if (bn_wexpand(rr, max) == NULL)\n        goto err;\n    if (al == 4) {\n#ifndef BN_SQR_COMBA\n        BN_ULONG t[8];\n        bn_sqr_normal(rr->d, a->d, 4, t);\n#else\n        bn_sqr_comba4(rr->d, a->d);\n#endif\n    } else if (al == 8) {\n#ifndef BN_SQR_COMBA\n        BN_ULONG t[16];\n        bn_sqr_normal(rr->d, a->d, 8, t);\n#else\n        bn_sqr_comba8(rr->d, a->d);\n#endif\n    } else {\n#if defined(BN_RECURSION)\n        if (al < BN_SQR_RECURSIVE_SIZE_NORMAL) {\n            BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL * 2];\n            bn_sqr_normal(rr->d, a->d, al, t);\n        } else {\n            int j, k;\n            j = BN_num_bits_word((BN_ULONG)al);\n            j = 1 << (j - 1);\n            k = j + j;\n            if (al == j) {\n                if (bn_wexpand(tmp, k * 2) == NULL)\n                    goto err;\n                bn_sqr_recursive(rr->d, a->d, al, tmp->d);\n            } else {\n                if (bn_wexpand(tmp, max) == NULL)\n                    goto err;\n                bn_sqr_normal(rr->d, a->d, al, tmp->d);\n            }\n        }\n#else\n        if (bn_wexpand(tmp, max) == NULL)\n            goto err;\n        bn_sqr_normal(rr->d, a->d, al, tmp->d);\n#endif\n    }\n    rr->neg = 0;\n    rr->top = max;\n    rr->flags |= BN_FLG_FIXED_TOP;\n    if (r != rr && BN_copy(r, rr) == NULL)\n        goto err;\n    ret = 1;\n err:\n    bn_check_top(rr);\n    bn_check_top(tmp);\n    BN_CTX_end(ctx);\n    return ret;\n}', 'int bn_div_fixed_top(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num,\n                     const BIGNUM *divisor, BN_CTX *ctx)\n{\n    int norm_shift, i, j, loop;\n    BIGNUM *tmp, *snum, *sdiv, *res;\n    BN_ULONG *resp, *wnum, *wnumtop;\n    BN_ULONG d0, d1;\n    int num_n, div_n;\n    assert(divisor->top > 0 && divisor->d[divisor->top - 1] != 0);\n    bn_check_top(num);\n    bn_check_top(divisor);\n    bn_check_top(dv);\n    bn_check_top(rm);\n    BN_CTX_start(ctx);\n    res = (dv == NULL) ? BN_CTX_get(ctx) : dv;\n    tmp = BN_CTX_get(ctx);\n    snum = BN_CTX_get(ctx);\n    sdiv = BN_CTX_get(ctx);\n    if (sdiv == NULL)\n        goto err;\n    if (!BN_copy(sdiv, divisor))\n        goto err;\n    norm_shift = bn_left_align(sdiv);\n    sdiv->neg = 0;\n    if (!(bn_lshift_fixed_top(snum, num, norm_shift)))\n        goto err;\n    div_n = sdiv->top;\n    num_n = snum->top;\n    if (num_n <= div_n) {\n        if (bn_wexpand(snum, div_n + 1) == NULL)\n            goto err;\n        memset(&(snum->d[num_n]), 0, (div_n - num_n + 1) * sizeof(BN_ULONG));\n        snum->top = num_n = div_n + 1;\n    }\n    loop = num_n - div_n;\n    wnum = &(snum->d[loop]);\n    wnumtop = &(snum->d[num_n - 1]);\n    d0 = sdiv->d[div_n - 1];\n    d1 = (div_n == 1) ? 0 : sdiv->d[div_n - 2];\n    if (!bn_wexpand(res, loop))\n        goto err;\n    res->neg = (num->neg ^ divisor->neg);\n    res->top = loop;\n    res->flags |= BN_FLG_FIXED_TOP;\n    resp = &(res->d[loop]);\n    if (!bn_wexpand(tmp, (div_n + 1)))\n        goto err;\n    for (i = 0; i < loop; i++, wnumtop--) {\n        BN_ULONG q, l0;\n# if defined(BN_DIV3W)\n        q = bn_div_3_words(wnumtop, d1, d0);\n# else\n        BN_ULONG n0, n1, rem = 0;\n        n0 = wnumtop[0];\n        n1 = wnumtop[-1];\n        if (n0 == d0)\n            q = BN_MASK2;\n        else {\n            BN_ULONG n2 = (wnumtop == wnum) ? 0 : wnumtop[-2];\n#  ifdef BN_LLONG\n            BN_ULLONG t2;\n#   if defined(BN_LLONG) && defined(BN_DIV2W) && !defined(bn_div_words)\n            q = (BN_ULONG)(((((BN_ULLONG) n0) << BN_BITS2) | n1) / d0);\n#   else\n            q = bn_div_words(n0, n1, d0);\n#   endif\n#   ifndef REMAINDER_IS_ALREADY_CALCULATED\n            rem = (n1 - q * d0) & BN_MASK2;\n#   endif\n            t2 = (BN_ULLONG) d1 *q;\n            for (;;) {\n                if (t2 <= ((((BN_ULLONG) rem) << BN_BITS2) | n2))\n                    break;\n                q--;\n                rem += d0;\n                if (rem < d0)\n                    break;\n                t2 -= d1;\n            }\n#  else\n            BN_ULONG t2l, t2h;\n            q = bn_div_words(n0, n1, d0);\n#   ifndef REMAINDER_IS_ALREADY_CALCULATED\n            rem = (n1 - q * d0) & BN_MASK2;\n#   endif\n#   if defined(BN_UMULT_LOHI)\n            BN_UMULT_LOHI(t2l, t2h, d1, q);\n#   elif defined(BN_UMULT_HIGH)\n            t2l = d1 * q;\n            t2h = BN_UMULT_HIGH(d1, q);\n#   else\n            {\n                BN_ULONG ql, qh;\n                t2l = LBITS(d1);\n                t2h = HBITS(d1);\n                ql = LBITS(q);\n                qh = HBITS(q);\n                mul64(t2l, t2h, ql, qh);\n            }\n#   endif\n            for (;;) {\n                if ((t2h < rem) || ((t2h == rem) && (t2l <= n2)))\n                    break;\n                q--;\n                rem += d0;\n                if (rem < d0)\n                    break;\n                if (t2l < d1)\n                    t2h--;\n                t2l -= d1;\n            }\n#  endif\n        }\n# endif\n        l0 = bn_mul_words(tmp->d, sdiv->d, div_n, q);\n        tmp->d[div_n] = l0;\n        wnum--;\n        l0 = bn_sub_words(wnum, wnum, tmp->d, div_n + 1);\n        q -= l0;\n        for (l0 = 0 - l0, j = 0; j < div_n; j++)\n            tmp->d[j] = sdiv->d[j] & l0;\n        l0 = bn_add_words(wnum, wnum, tmp->d, div_n);\n        (*wnumtop) += l0;\n        assert((*wnumtop) == 0);\n        *--resp = q;\n    }\n    snum->neg = num->neg;\n    snum->top = div_n;\n    snum->flags |= BN_FLG_FIXED_TOP;\n    if (rm != NULL)\n        bn_rshift_fixed_top(rm, snum, norm_shift);\n    BN_CTX_end(ctx);\n    return 1;\n err:\n    bn_check_top(rm);\n    BN_CTX_end(ctx);\n    return 0;\n}', 'void BN_CTX_end(BN_CTX *ctx)\n{\n    CTXDBG("ENTER BN_CTX_end()", ctx);\n    if (ctx->err_stack)\n        ctx->err_stack--;\n    else {\n        unsigned int fp = BN_STACK_pop(&ctx->stack);\n        if (fp < ctx->used)\n            BN_POOL_release(&ctx->pool, ctx->used - fp);\n        ctx->used = fp;\n        ctx->too_many = 0;\n    }\n    CTXDBG("LEAVE BN_CTX_end()", ctx);\n}', 'static unsigned int BN_STACK_pop(BN_STACK *st)\n{\n    return st->indexes[--(st->depth)];\n}']