sba: Move the sba code to a dedicated file

Move the code around and then turn it into an object...
diff --git a/src/sba.cpp b/src/sba.cpp
new file mode 100644
index 0000000..f002649
--- /dev/null
+++ b/src/sba.cpp
@@ -0,0 +1,121 @@
+/* sba.cpp
+ *
+ * Copyright (C) 2012 Ivan Klyuchnikov
+ * Copyright (C) 2012 Andreas Eversberg <jolly@eversberg.eu>
+ * Copyright (C) 2013 by Holger Hans Peter Freyther
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+
+#include <gprs_rlcmac.h>
+#include <gprs_debug.h>
+#include <bts.h>
+
+extern "C" {
+#include <osmocom/core/talloc.h>
+}
+
+#include <errno.h>
+
+extern void *tall_pcu_ctx;
+
+/* starting time for assigning single slot
+ * This offset must be a multiple of 13. */
+#define AGCH_START_OFFSET 52
+
+LLIST_HEAD(gprs_rlcmac_sbas);
+
+int sba_alloc(struct gprs_rlcmac_bts *bts,
+		uint8_t *_trx, uint8_t *_ts, uint32_t *_fn, uint8_t ta)
+{
+
+	struct gprs_rlcmac_pdch *pdch;
+	struct gprs_rlcmac_sba *sba;
+	uint8_t trx, ts;
+	uint32_t fn;
+
+	sba = talloc_zero(tall_pcu_ctx, struct gprs_rlcmac_sba);
+	if (!sba)
+		return -ENOMEM;
+
+	for (trx = 0; trx < 8; trx++) {
+		for (ts = 0; ts < 8; ts++) {
+			pdch = &bts->trx[trx].pdch[ts];
+			if (!pdch->is_enabled())
+				continue;
+			break;
+		}
+		if (ts < 8)
+			break;
+	}
+	if (trx == 8) {
+		LOGP(DRLCMAC, LOGL_NOTICE, "No PDCH available.\n");
+		talloc_free(sba);
+		return -EINVAL;
+	}
+
+	fn = (pdch->last_rts_fn + AGCH_START_OFFSET) % 2715648;
+
+	sba->trx = trx;
+	sba->ts = ts;
+	sba->fn = fn;
+	sba->ta = ta;
+
+	llist_add(&sba->list, &gprs_rlcmac_sbas);
+
+	*_trx = trx;
+	*_ts = ts;
+	*_fn = fn;
+	return 0;
+}
+
+struct gprs_rlcmac_sba *sba_find(uint8_t trx, uint8_t ts, uint32_t fn)
+{
+	struct gprs_rlcmac_sba *sba;
+
+	llist_for_each_entry(sba, &gprs_rlcmac_sbas, list) {
+		if (sba->trx == trx && sba->ts == ts && sba->fn == fn)
+			return sba;
+	}
+
+	return NULL;
+}
+
+uint32_t sched_sba(uint8_t trx, uint8_t ts, uint32_t fn, uint8_t block_nr)
+{
+	uint32_t sba_fn;
+	struct gprs_rlcmac_sba *sba;
+
+	/* check special TBF for events */
+	sba_fn = fn + 4;
+	if ((block_nr % 3) == 2)
+		sba_fn ++;
+	sba_fn = sba_fn % 2715648;
+	sba = sba_find(trx, ts, sba_fn);
+	if (sba)
+		return sba_fn;
+
+	return 0xffffffff;
+}
+
+int gprs_rlcmac_sba_timeout(struct gprs_rlcmac_sba *sba)
+{
+	LOGP(DRLCMAC, LOGL_NOTICE, "Poll timeout for SBA\n");
+	llist_del(&sba->list);
+	talloc_free(sba);
+
+	return 0;
+}
+