Introducing scheduler to process transmission of blocks

The scheduler is triggered at ready-to-send-requesst. It schedules
control blocks, data block and dummy blocks, depending on priority.

It provides upstream ressource by setting USF. The ressources are
assigned, if required. The ressources are dispatched round-robin.

In case of polling, the upstream ressource is given to MS at the
time it will respond to polling request.

1 files changed, 176 insertions, 0 deletions

diff --git a/src/gprs_rlcmac_sched.cpp b/src/gprs_rlcmac_sched.cpp
new file mode 100644
index 00000000..6ccb26c7
--- /dev/null
+++ b/src/gprs_rlcmac_sched.cpp
@@ -0,0 +1,176 @@
+/* PDCH scheduler
+ *
+ * Copyright (C) 2012 Andreas Eversberg <jolly@eversberg.eu>
+ *
+ * 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_bssgp_pcu.h>
+#include <gprs_rlcmac.h>
+#include <pcu_l1_if.h>
+
+extern struct llist_head block_queue;
+
+static uint8_t rlcmac_dl_idle[23] = {
+	0x47, /* control without optional header octets, no polling, USF=111 */
+	0x94, /* dummy downlink control message, paging mode 00 */
+	0x2b, /* no persistance level, 7 bits spare pattern */
+	0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b,
+	0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b
+};
+
+int gprs_rlcmac_rcv_rts_block(uint8_t trx, uint8_t ts, uint16_t arfcn,
+        uint32_t fn, uint8_t block_nr)
+{
+	struct gprs_rlcmac_bts *bts = gprs_rlcmac_bts;
+	struct gprs_rlcmac_pdch *pdch;
+	struct gprs_rlcmac_tbf *tbf;
+	uint8_t usf = 0x7;
+	struct msgb *msg = NULL;
+	uint32_t poll_fn;
+	uint8_t i, tfi;
+
+	if (trx >= 8 || ts >= 8)
+		return -EINVAL;
+	pdch = &bts->trx[trx].pdch[ts];
+
+	if (!pdch->enable) {
+		LOGP(DRLCMACSCHED, LOGL_ERROR, "Received RTS on disabled PDCH: "
+			"TRX=%d TS=%d\n", trx, ts);
+		return -EIO;
+	}
+
+	/* check uplink ressource for polling */
+	poll_fn = fn + 4;
+	if ((block_nr % 3) == 2)
+		poll_fn ++;
+	poll_fn = poll_fn % 2715648;
+	for (tfi = 0; tfi < 32; tfi++) {
+		tbf = pdch->tbf[tfi];
+		/* no TBF for this tfi, go next */
+		if (!tbf)
+			continue;
+		/* no polling */
+		if (tbf->poll_state != GPRS_RLCMAC_POLL_SCHED)
+			continue;
+		/* polling for next uplink block */
+		if (tbf->poll_fn == poll_fn)
+			break;
+	}
+	/* found uplink where a block is polled */
+	if (tfi < 32) {
+		LOGP(DRLCMACSCHED, LOGL_DEBUG, "Received RTS for PDCH: TRX=%d "
+			"TS=%d FN=%d block_nr=%d scheduling free USF for "
+			"polling at FN=%d of TFI=%d\n", trx, ts, fn, block_nr,
+			poll_fn, tfi);
+		/* reset poll state */
+		tbf->poll_state = GPRS_RLCMAC_POLL_NONE;
+		/* use free USF */
+	/* else, we search for uplink ressource */
+	} else {
+		/* select uplink ressource */
+		for (i = 0, tfi = pdch->next_ul_tfi; i < 32;
+		     i++, tfi = (tfi + 1) & 31) {
+			tbf = pdch->tbf[tfi];
+			/* no TBF for this tfi, go next */
+			if (!tbf)
+				continue;
+			/* no UL TBF, go next */
+			if (tbf->direction != GPRS_RLCMAC_UL_TBF)
+				continue;
+			/* no UL ressources needed, go next */
+			if (tbf->state != GPRS_RLCMAC_FLOW)
+				continue;
+			break;
+		}
+		if (i < 32) {
+			/* use this USF */
+			usf = tbf->dir.ul.usf;
+			LOGP(DRLCMACSCHED, LOGL_DEBUG, "Received RTS for PDCH: "
+				"TRX=%d TS=%d FN=%d block_nr=%d scheduling "
+				"USF=%d for required uplink ressource of "
+				"TFB=%d\n", trx, ts, fn, block_nr, usf, tfi);
+			/* next TFB to handle ressource is the next one */
+			pdch->next_ul_tfi = (tfi + 1) & 31;
+		}
+	}
+
+	/* Prio 1: select control message */
+	if (!msg) {
+		for (tfi = 0; tfi < 32; tfi++) {
+			tbf = pdch->tbf[tfi];
+			/* no TBF for this tfi, go next */
+			if (!tbf)
+				continue;
+			/* no UL TBF, go next */
+			if (tbf->direction != GPRS_RLCMAC_UL_TBF)
+				continue;
+			if (tbf->dir.ul.substate == GPRS_RLCMAC_UL_SEND_ACK)
+				break;
+		}
+		if (tfi < 32) {
+			LOGP(DRLCMACSCHED, LOGL_DEBUG, "Scheduling control "
+				"message at RTS for TFB=%d\n", tfi);
+			/* generate ack message */
+			msg = gprs_rlcmac_send_uplink_ack(tbf, fn);
+		}
+	}
+
+	/* Prio 2: select data message for downlink */
+	if (!msg) {
+		/* select downlink ressource */
+		for (i = 0, tfi = pdch->next_dl_tfi; i < 32;
+		     i++, tfi = (tfi + 1) & 31) {
+			tbf = pdch->tbf[tfi];
+			/* no TBF for this tfi, go next */
+			if (!tbf)
+				continue;
+			/* no DD TBF, go next */
+			if (tbf->direction != GPRS_RLCMAC_DL_TBF)
+				continue;
+			/* FIXME: */
+		}
+		if (i < 32) {
+			LOGP(DRLCMACSCHED, LOGL_DEBUG, "Scheduling data "
+				"message at RTS for TFB=%d\n", tfi);
+			/* next TFB to handle ressource is the next one */
+			pdch->next_dl_tfi = (tfi + 1) & 31;
+			/* generate ack message */
+			/* FIXME: */
+		}
+/* FIXME: remove that when DL TBF is finished */
+set_current_fn(fn);
+msg = msgb_dequeue(&block_queue);
+	}
+
+	/* Prio 3: send dummy contol message */
+	if (!msg) {
+		msg = msgb_alloc(23, "rlcmac_dl_idle");
+		if (!msg)
+			return -ENOMEM;
+		memcpy(msgb_put(msg, 23), rlcmac_dl_idle, 23);
+	}
+	/* msg is now available */
+
+	/* set USF */
+	msg->data[0] = (msg->data[0] & 0xf8) | usf;
+
+//	printf("len=%d, date=%s\n", msg->len, osmo_hexdump(msg->data, msg->len));
+
+	/* send PDTCH/PACCH to L1 */
+	pcu_l1if_tx_pdtch(msg, trx, ts, arfcn, fn, block_nr);
+
+	return 0;
+}