l1/interleave: Add interleaving primitives (intra-burst only so far)

As described in GMR-1 05.003 Section 4.8

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

1 files changed, 82 insertions, 0 deletions

diff --git a/src/l1/interleave.c b/src/l1/interleave.c
new file mode 100644
index 0000000..38ef6c9
--- /dev/null
+++ b/src/l1/interleave.c
@@ -0,0 +1,82 @@
+/* GMR-1 interleaving */
+/* See GMR-1 05.003 (ETSI TS 101 376-5-3 V1.2.1) - Section 4.8 */
+
+/* (C) 2011 by Sylvain Munaut <tnt@246tNt.com>
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*! \addtogroup interleave
+ *  @{
+ */
+
+/*! \file interleave.c
+ *  \file Osmocom GMR-1 interleaving implementation
+ */
+
+#include <stdint.h>
+
+
+/*! \brief GMR-1 intra burst inteleaver
+ *  \param[out] out Interleaved bit array to write to
+ *  \param[in] in Original bit array to read from
+ *  \param[in] N Dimension of the interleaving matrix
+ *
+ * Both arrays need to have a length of (8*N).
+ * This routine works for any type that has the same size as uint8_t like
+ * sbit_t or ubit_t.
+ */
+void
+gmr1_interleave_intra(void *out, void *in, int N)
+{
+	const uint8_t *inb = (uint8_t *)in;
+	uint8_t *outb = (uint8_t *)out;
+	int len = N << 3;
+	int kc, kep, i, j;
+
+	for (kc=0; kc<len; kc++) {
+		i = kc >> 3;
+		j = (5 * kc) & 7;
+		kep = N * j + i;
+		outb[kep] = inb[kc];
+	}
+}
+
+/*! \brief GMR-1 intra burst de-interleaver
+ *  \param[out] out Deinterleaved bit array to write to
+ *  \param[in] in Interleaved bit array to read from
+ *  \param[in] N Dimension of the interleaving matrix
+ *
+ * Both arrays need to have a length of (8*N).
+ * This routine works for any type that has the same size as uint8_t like
+ * sbit_t or ubit_t.
+ */
+void
+gmr1_deinterleave_intra(void *out, void *in, int N)
+{
+	const uint8_t *inb = (uint8_t *)in;
+	uint8_t *outb = (uint8_t *)out;
+	int len = N << 3;
+	int kc, kep, i, j;
+
+	for (kc=0; kc<len; kc++) {
+		i = kc >> 3;
+		j = (5 * kc) & 7;
+		kep = N * j + i;
+		outb[kc] = inb[kep];
+	}
+}
+
+/*! }@ */