core/conv: use proper filenames

We already have generic convolutional transcoding implementation
written by Sylvain Munaut and named 'conv.c', so 'viterbi_*' names
looked a bit confusing.

Let's use a single naming scheme for Viterbi related code.

Change-Id: I61062a8d1fbf5f5fc85b4fac58dc4e9fa8b5ef90

1 files changed, 207 insertions, 0 deletions

diff --git a/src/conv_acc_generic.c b/src/conv_acc_generic.c
new file mode 100644
index 00000000..60426685
--- /dev/null
+++ b/src/conv_acc_generic.c
@@ -0,0 +1,207 @@
+/*
+ * Viterbi decoder
+ *
+ * Copyright (C) 2013, 2014 Thomas Tsou <tom@tsou.cc>
+ *
+ * All Rights Reserved
+ *
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+
+/* Add-Compare-Select (ACS-Butterfly)
+ * Compute 4 accumulated path metrics and 4 path selections. Note that path
+ * selections are store as -1 and 0 rather than 0 and 1. This is to match
+ * the output format of the SSE packed compare instruction 'pmaxuw'.
+ */
+
+static void acs_butterfly(int state, int num_states,
+	int16_t metric, int16_t *sum,
+	int16_t *new_sum, int16_t *path)
+{
+	int state0, state1;
+	int sum0, sum1, sum2, sum3;
+
+	state0 = *(sum + (2 * state + 0));
+	state1 = *(sum + (2 * state + 1));
+
+	sum0 = state0 + metric;
+	sum1 = state1 - metric;
+	sum2 = state0 - metric;
+	sum3 = state1 + metric;
+
+	if (sum0 >= sum1) {
+		*new_sum = sum0;
+		*path = -1;
+	} else {
+		*new_sum = sum1;
+		*path = 0;
+	}
+
+	if (sum2 >= sum3) {
+		*(new_sum + num_states / 2) = sum2;
+		*(path + num_states / 2) = -1;
+	} else {
+		*(new_sum + num_states / 2) = sum3;
+		*(path + num_states / 2) = 0;
+	}
+}
+
+/* Branch metrics unit N=2 */
+static void gen_branch_metrics_n2(int num_states, const int8_t *seq,
+	const int16_t *out, int16_t *metrics)
+{
+	int i;
+
+	for (i = 0; i < num_states / 2; i++) {
+		metrics[i] = seq[0] * out[2 * i + 0] +
+			seq[1] * out[2 * i + 1];
+	}
+}
+
+/* Branch metrics unit N=3 */
+static void gen_branch_metrics_n3(int num_states, const int8_t *seq,
+	const int16_t *out, int16_t *metrics)
+{
+	int i;
+
+	for (i = 0; i < num_states / 2; i++) {
+		metrics[i] = seq[0] * out[4 * i + 0] +
+			seq[1] * out[4 * i + 1] +
+			seq[2] * out[4 * i + 2];
+	}
+}
+
+/* Branch metrics unit N=4 */
+static void gen_branch_metrics_n4(int num_states, const int8_t *seq,
+	const int16_t *out, int16_t *metrics)
+{
+	int i;
+
+	for (i = 0; i < num_states / 2; i++) {
+		metrics[i] = seq[0] * out[4 * i + 0] +
+			seq[1] * out[4 * i + 1] +
+			seq[2] * out[4 * i + 2] +
+			seq[3] * out[4 * i + 3];
+	}
+}
+
+/* Path metric unit */
+static void gen_path_metrics(int num_states, int16_t *sums,
+	int16_t *metrics, int16_t *paths, int norm)
+{
+	int i;
+	int16_t min;
+	int16_t new_sums[num_states];
+
+	for (i = 0; i < num_states / 2; i++)
+		acs_butterfly(i, num_states, metrics[i],
+			sums, &new_sums[i], &paths[i]);
+
+	if (norm) {
+		min = new_sums[0];
+
+		for (i = 1; i < num_states; i++)
+			if (new_sums[i] < min)
+				min = new_sums[i];
+
+		for (i = 0; i < num_states; i++)
+			new_sums[i] -= min;
+	}
+
+	memcpy(sums, new_sums, num_states * sizeof(int16_t));
+}
+
+/* Not-aligned Memory Allocator */
+__attribute__ ((visibility("hidden")))
+int16_t *osmo_conv_gen_vdec_malloc(size_t n)
+{
+	return (int16_t *) malloc(sizeof(int16_t) * n);
+}
+
+__attribute__ ((visibility("hidden")))
+void osmo_conv_gen_vdec_free(int16_t *ptr)
+{
+	free(ptr);
+}
+
+/* 16-state branch-path metrics units (K=5) */
+__attribute__ ((visibility("hidden")))
+void osmo_conv_gen_metrics_k5_n2(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm)
+{
+	int16_t metrics[8];
+
+	gen_branch_metrics_n2(16, seq, out, metrics);
+	gen_path_metrics(16, sums, metrics, paths, norm);
+}
+
+__attribute__ ((visibility("hidden")))
+void osmo_conv_gen_metrics_k5_n3(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm)
+{
+	int16_t metrics[8];
+
+	gen_branch_metrics_n3(16, seq, out, metrics);
+	gen_path_metrics(16, sums, metrics, paths, norm);
+
+}
+
+__attribute__ ((visibility("hidden")))
+void osmo_conv_gen_metrics_k5_n4(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm)
+{
+	int16_t metrics[8];
+
+	gen_branch_metrics_n4(16, seq, out, metrics);
+	gen_path_metrics(16, sums, metrics, paths, norm);
+
+}
+
+/* 64-state branch-path metrics units (K=7) */
+__attribute__ ((visibility("hidden")))
+void osmo_conv_gen_metrics_k7_n2(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm)
+{
+	int16_t metrics[32];
+
+	gen_branch_metrics_n2(64, seq, out, metrics);
+	gen_path_metrics(64, sums, metrics, paths, norm);
+
+}
+
+__attribute__ ((visibility("hidden")))
+void osmo_conv_gen_metrics_k7_n3(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm)
+{
+	int16_t metrics[32];
+
+	gen_branch_metrics_n3(64, seq, out, metrics);
+	gen_path_metrics(64, sums, metrics, paths, norm);
+
+}
+
+__attribute__ ((visibility("hidden")))
+void osmo_conv_gen_metrics_k7_n4(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm)
+{
+	int16_t metrics[32];
+
+	gen_branch_metrics_n4(64, seq, out, metrics);
+	gen_path_metrics(64, sums, metrics, paths, norm);
+}