static unsigned int BN_STACK_pop(BN_STACK *st)
{
    return st->indexes[--(st->depth)];
}
['static int ec_mul_consttime(const EC_GROUP *group, EC_POINT *r,\n                            const BIGNUM *scalar, const EC_POINT *point,\n                            BN_CTX *ctx)\n{\n    int i, cardinality_bits, group_top, kbit, pbit, Z_is_one;\n    EC_POINT *s = NULL;\n    BIGNUM *k = NULL;\n    BIGNUM *lambda = NULL;\n    BIGNUM *cardinality = NULL;\n    BN_CTX *new_ctx = NULL;\n    int ret = 0;\n    if (ctx == NULL && (ctx = new_ctx = BN_CTX_secure_new()) == NULL)\n        return 0;\n    BN_CTX_start(ctx);\n    s = EC_POINT_new(group);\n    if (s == NULL)\n        goto err;\n    if (point == NULL) {\n        if (!EC_POINT_copy(s, group->generator))\n            goto err;\n    } else {\n        if (!EC_POINT_copy(s, point))\n            goto err;\n    }\n    EC_POINT_BN_set_flags(s, BN_FLG_CONSTTIME);\n    cardinality = BN_CTX_get(ctx);\n    lambda = BN_CTX_get(ctx);\n    k = BN_CTX_get(ctx);\n    if (k == NULL || !BN_mul(cardinality, group->order, group->cofactor, ctx))\n        goto err;\n    cardinality_bits = BN_num_bits(cardinality);\n    group_top = bn_get_top(cardinality);\n    if ((bn_wexpand(k, group_top + 1) == NULL)\n        || (bn_wexpand(lambda, group_top + 1) == NULL))\n        goto err;\n    if (!BN_copy(k, scalar))\n        goto err;\n    BN_set_flags(k, BN_FLG_CONSTTIME);\n    if ((BN_num_bits(k) > cardinality_bits) || (BN_is_negative(k))) {\n        if (!BN_nnmod(k, k, cardinality, ctx))\n            goto err;\n    }\n    if (!BN_add(lambda, k, cardinality))\n        goto err;\n    BN_set_flags(lambda, BN_FLG_CONSTTIME);\n    if (!BN_add(k, lambda, cardinality))\n        goto err;\n    kbit = BN_is_bit_set(lambda, cardinality_bits);\n    BN_consttime_swap(kbit, k, lambda, group_top + 1);\n    group_top = bn_get_top(group->field);\n    if ((bn_wexpand(s->X, group_top) == NULL)\n        || (bn_wexpand(s->Y, group_top) == NULL)\n        || (bn_wexpand(s->Z, group_top) == NULL)\n        || (bn_wexpand(r->X, group_top) == NULL)\n        || (bn_wexpand(r->Y, group_top) == NULL)\n        || (bn_wexpand(r->Z, group_top) == NULL))\n        goto err;\n    if (!ec_point_blind_coordinates(group, s, ctx))\n        goto err;\n    if (!EC_POINT_copy(r, s))\n        goto err;\n    EC_POINT_BN_set_flags(r, BN_FLG_CONSTTIME);\n    if (!EC_POINT_dbl(group, s, s, ctx))\n        goto err;\n    pbit = 0;\n#define EC_POINT_CSWAP(c, a, b, w, t) do {         \\\n        BN_consttime_swap(c, (a)->X, (b)->X, w);   \\\n        BN_consttime_swap(c, (a)->Y, (b)->Y, w);   \\\n        BN_consttime_swap(c, (a)->Z, (b)->Z, w);   \\\n        t = ((a)->Z_is_one ^ (b)->Z_is_one) & (c); \\\n        (a)->Z_is_one ^= (t);                      \\\n        (b)->Z_is_one ^= (t);                      \\\n} while(0)\n    for (i = cardinality_bits - 1; i >= 0; i--) {\n        kbit = BN_is_bit_set(k, i) ^ pbit;\n        EC_POINT_CSWAP(kbit, r, s, group_top, Z_is_one);\n        if (!EC_POINT_add(group, s, r, s, ctx))\n            goto err;\n        if (!EC_POINT_dbl(group, r, r, ctx))\n            goto err;\n        pbit ^= kbit;\n    }\n    EC_POINT_CSWAP(pbit, r, s, group_top, Z_is_one);\n#undef EC_POINT_CSWAP\n    ret = 1;\n err:\n    EC_POINT_free(s);\n    BN_CTX_end(ctx);\n    BN_CTX_free(new_ctx);\n    return ret;\n}', 'void BN_CTX_start(BN_CTX *ctx)\n{\n    CTXDBG_ENTRY("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_EXIT(ctx);\n}', 'int BN_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)\n{\n    int ret = 0;\n    int top, al, bl;\n    BIGNUM *rr;\n#if defined(BN_MUL_COMBA) || defined(BN_RECURSION)\n    int i;\n#endif\n#ifdef BN_RECURSION\n    BIGNUM *t = NULL;\n    int j = 0, k;\n#endif\n    bn_check_top(a);\n    bn_check_top(b);\n    bn_check_top(r);\n    al = a->top;\n    bl = b->top;\n    if ((al == 0) || (bl == 0)) {\n        BN_zero(r);\n        return 1;\n    }\n    top = al + bl;\n    BN_CTX_start(ctx);\n    if ((r == a) || (r == b)) {\n        if ((rr = BN_CTX_get(ctx)) == NULL)\n            goto err;\n    } else\n        rr = r;\n#if defined(BN_MUL_COMBA) || defined(BN_RECURSION)\n    i = al - bl;\n#endif\n#ifdef BN_MUL_COMBA\n    if (i == 0) {\n# if 0\n        if (al == 4) {\n            if (bn_wexpand(rr, 8) == NULL)\n                goto err;\n            rr->top = 8;\n            bn_mul_comba4(rr->d, a->d, b->d);\n            goto end;\n        }\n# endif\n        if (al == 8) {\n            if (bn_wexpand(rr, 16) == NULL)\n                goto err;\n            rr->top = 16;\n            bn_mul_comba8(rr->d, a->d, b->d);\n            goto end;\n        }\n    }\n#endif\n#ifdef BN_RECURSION\n    if ((al >= BN_MULL_SIZE_NORMAL) && (bl >= BN_MULL_SIZE_NORMAL)) {\n        if (i >= -1 && i <= 1) {\n            if (i >= 0) {\n                j = BN_num_bits_word((BN_ULONG)al);\n            }\n            if (i == -1) {\n                j = BN_num_bits_word((BN_ULONG)bl);\n            }\n            j = 1 << (j - 1);\n            assert(j <= al || j <= bl);\n            k = j + j;\n            t = BN_CTX_get(ctx);\n            if (t == NULL)\n                goto err;\n            if (al > j || bl > j) {\n                if (bn_wexpand(t, k * 4) == NULL)\n                    goto err;\n                if (bn_wexpand(rr, k * 4) == NULL)\n                    goto err;\n                bn_mul_part_recursive(rr->d, a->d, b->d,\n                                      j, al - j, bl - j, t->d);\n            } else {\n                if (bn_wexpand(t, k * 2) == NULL)\n                    goto err;\n                if (bn_wexpand(rr, k * 2) == NULL)\n                    goto err;\n                bn_mul_recursive(rr->d, a->d, b->d, j, al - j, bl - j, t->d);\n            }\n            rr->top = top;\n            goto end;\n        }\n    }\n#endif\n    if (bn_wexpand(rr, top) == NULL)\n        goto err;\n    rr->top = top;\n    bn_mul_normal(rr->d, a->d, al, b->d, bl);\n#if defined(BN_MUL_COMBA) || defined(BN_RECURSION)\n end:\n#endif\n    rr->neg = a->neg ^ b->neg;\n    bn_correct_top(rr);\n    if (r != rr && BN_copy(r, rr) == NULL)\n        goto err;\n    ret = 1;\n err:\n    bn_check_top(r);\n    BN_CTX_end(ctx);\n    return ret;\n}', 'void BN_CTX_end(BN_CTX *ctx)\n{\n    CTXDBG_ENTRY("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_EXIT(ctx);\n}', 'static unsigned int BN_STACK_pop(BN_STACK *st)\n{\n    return st->indexes[--(st->depth)];\n}']