static unsigned int BN_STACK_pop(BN_STACK *st)
{
    return st->indexes[--(st->depth)];
}
['static BIGNUM *rsa_get_public_exp(const BIGNUM *d, const BIGNUM *p,\n                                  const BIGNUM *q, BN_CTX *ctx)\n{\n    BIGNUM *ret = NULL, *r0, *r1, *r2;\n    if (d == NULL || p == NULL || q == NULL)\n        return NULL;\n    BN_CTX_start(ctx);\n    r0 = BN_CTX_get(ctx);\n    r1 = BN_CTX_get(ctx);\n    r2 = BN_CTX_get(ctx);\n    if (r2 == NULL)\n        goto err;\n    if (!BN_sub(r1, p, BN_value_one()))\n        goto err;\n    if (!BN_sub(r2, q, BN_value_one()))\n        goto err;\n    if (!BN_mul(r0, r1, r2, ctx))\n        goto err;\n    ret = BN_mod_inverse(NULL, d, r0, ctx);\n err:\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}', '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}']