static unsigned int BN_STACK_pop(BN_STACK *st)
{
    return st->indexes[--(st->depth)];
}
['int rsa_check_private_exponent(const RSA *rsa, int nbits, BN_CTX *ctx)\n{\n    int ret;\n    BIGNUM *r, *p1, *q1, *lcm, *p1q1, *gcd;\n    if (BN_num_bits(rsa->d) <= (nbits >> 1))\n        return 0;\n    BN_CTX_start(ctx);\n    r = BN_CTX_get(ctx);\n    p1 = BN_CTX_get(ctx);\n    q1 = BN_CTX_get(ctx);\n    lcm = BN_CTX_get(ctx);\n    p1q1 = BN_CTX_get(ctx);\n    gcd = BN_CTX_get(ctx);\n    ret = (gcd != NULL\n          && (rsa_get_lcm(ctx, rsa->p, rsa->q, lcm, gcd, p1, q1, p1q1) == 1)\n          && (BN_cmp(rsa->d, lcm) < 0)\n          && BN_mod_mul(r, rsa->e, rsa->d, lcm, ctx)\n          && BN_is_one(r));\n    BN_clear(p1);\n    BN_clear(q1);\n    BN_clear(lcm);\n    BN_clear(gcd);\n    BN_CTX_end(ctx);\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}', '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}']