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, 728 insertions, 0 deletions

diff --git a/src/conv_acc.c b/src/conv_acc.c
new file mode 100644
index 00000000..308cfe07
--- /dev/null
+++ b/src/conv_acc.c
@@ -0,0 +1,728 @@
+/*
+ * 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 <string.h>
+#include <errno.h>
+
+#include "config.h"
+
+#include <osmocom/core/conv.h>
+
+#define BIT2NRZ(REG,N)	(((REG >> N) & 0x01) * 2 - 1) * -1
+#define NUM_STATES(K)	(K == 7 ? 64 : 16)
+
+#define INIT_POINTERS(simd) \
+{ \
+	osmo_conv_metrics_k5_n2 = osmo_conv_##simd##_metrics_k5_n2; \
+	osmo_conv_metrics_k5_n3 = osmo_conv_##simd##_metrics_k5_n3; \
+	osmo_conv_metrics_k5_n4 = osmo_conv_##simd##_metrics_k5_n4; \
+	osmo_conv_metrics_k7_n2 = osmo_conv_##simd##_metrics_k7_n2; \
+	osmo_conv_metrics_k7_n3 = osmo_conv_##simd##_metrics_k7_n3; \
+	osmo_conv_metrics_k7_n4 = osmo_conv_##simd##_metrics_k7_n4; \
+	vdec_malloc = &osmo_conv_##simd##_vdec_malloc; \
+	vdec_free = &osmo_conv_##simd##_vdec_free; \
+}
+
+static int init_complete = 0;
+
+__attribute__ ((visibility("hidden"))) int avx2_supported = 0;
+__attribute__ ((visibility("hidden"))) int sse3_supported = 0;
+__attribute__ ((visibility("hidden"))) int sse41_supported = 0;
+
+/**
+ * These pointers are being initialized at runtime by the
+ * osmo_conv_init() depending on supported SIMD extensions.
+ */
+static int16_t *(*vdec_malloc)(size_t n);
+static void (*vdec_free)(int16_t *ptr);
+
+void (*osmo_conv_metrics_k5_n2)(const int8_t *seq,
+	const int16_t *out, int16_t *sums, int16_t *paths, int norm);
+void (*osmo_conv_metrics_k5_n3)(const int8_t *seq,
+	const int16_t *out, int16_t *sums, int16_t *paths, int norm);
+void (*osmo_conv_metrics_k5_n4)(const int8_t *seq,
+	const int16_t *out, int16_t *sums, int16_t *paths, int norm);
+void (*osmo_conv_metrics_k7_n2)(const int8_t *seq,
+	const int16_t *out, int16_t *sums, int16_t *paths, int norm);
+void (*osmo_conv_metrics_k7_n3)(const int8_t *seq,
+	const int16_t *out, int16_t *sums, int16_t *paths, int norm);
+void (*osmo_conv_metrics_k7_n4)(const int8_t *seq,
+	const int16_t *out, int16_t *sums, int16_t *paths, int norm);
+
+/* Forward malloc wrappers */
+int16_t *osmo_conv_gen_vdec_malloc(size_t n);
+void osmo_conv_gen_vdec_free(int16_t *ptr);
+
+#if defined(HAVE_SSE3)
+int16_t *osmo_conv_sse_vdec_malloc(size_t n);
+void osmo_conv_sse_vdec_free(int16_t *ptr);
+#endif
+
+#if defined(HAVE_SSE3) && defined(HAVE_AVX2)
+int16_t *osmo_conv_sse_avx_vdec_malloc(size_t n);
+void osmo_conv_sse_avx_vdec_free(int16_t *ptr);
+#endif
+
+/* Forward Metric Units */
+void osmo_conv_gen_metrics_k5_n2(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+void osmo_conv_gen_metrics_k5_n3(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+void osmo_conv_gen_metrics_k5_n4(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+void osmo_conv_gen_metrics_k7_n2(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+void osmo_conv_gen_metrics_k7_n3(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+void osmo_conv_gen_metrics_k7_n4(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+
+#if defined(HAVE_SSE3)
+void osmo_conv_sse_metrics_k5_n2(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+void osmo_conv_sse_metrics_k5_n3(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+void osmo_conv_sse_metrics_k5_n4(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+void osmo_conv_sse_metrics_k7_n2(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+void osmo_conv_sse_metrics_k7_n3(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+void osmo_conv_sse_metrics_k7_n4(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+#endif
+
+#if defined(HAVE_SSE3) && defined(HAVE_AVX2)
+void osmo_conv_sse_avx_metrics_k5_n2(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+void osmo_conv_sse_avx_metrics_k5_n3(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+void osmo_conv_sse_avx_metrics_k5_n4(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+void osmo_conv_sse_avx_metrics_k7_n2(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+void osmo_conv_sse_avx_metrics_k7_n3(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+void osmo_conv_sse_avx_metrics_k7_n4(const int8_t *seq, const int16_t *out,
+	int16_t *sums, int16_t *paths, int norm);
+#endif
+
+/* Trellis State
+ * state - Internal lshift register value
+ * prev  - Register values of previous 0 and 1 states
+ */
+struct vstate {
+	unsigned state;
+	unsigned prev[2];
+};
+
+/* Trellis Object
+ * num_states - Number of states in the trellis
+ * sums       - Accumulated path metrics
+ * outputs    - Trellis output values
+ * vals       - Input value that led to each state
+ */
+struct vtrellis {
+	int num_states;
+	int16_t *sums;
+	int16_t *outputs;
+	uint8_t *vals;
+};
+
+/* Viterbi Decoder
+ * n         - Code order
+ * k         - Constraint length
+ * len       - Horizontal length of trellis
+ * recursive - Set to '1' if the code is recursive
+ * intrvl    - Normalization interval
+ * trellis   - Trellis object
+ * punc      - Puncturing sequence
+ * paths     - Trellis paths
+ */
+struct vdecoder {
+	int n;
+	int k;
+	int len;
+	int recursive;
+	int intrvl;
+	struct vtrellis *trellis;
+	int *punc;
+	int16_t **paths;
+
+	void (*metric_func)(const int8_t *, const int16_t *,
+		int16_t *, int16_t *, int);
+};
+
+/* Accessor calls */
+static inline int conv_code_recursive(const struct osmo_conv_code *code)
+{
+	return code->next_term_output ? 1 : 0;
+}
+
+/* Left shift and mask for finding the previous state */
+static unsigned vstate_lshift(unsigned reg, int k, int val)
+{
+	unsigned mask;
+
+	if (k == 5)
+		mask = 0x0e;
+	else if (k == 7)
+		mask = 0x3e;
+	else
+		mask = 0;
+
+	return ((reg << 1) & mask) | val;
+}
+
+/* Bit endian manipulators */
+static inline unsigned bitswap2(unsigned v)
+{
+	return ((v & 0x02) >> 1) | ((v & 0x01) << 1);
+}
+
+static inline unsigned bitswap3(unsigned v)
+{
+	return ((v & 0x04) >> 2) | ((v & 0x02) >> 0) |
+		((v & 0x01) << 2);
+}
+
+static inline unsigned bitswap4(unsigned v)
+{
+	return ((v & 0x08) >> 3) | ((v & 0x04) >> 1) |
+		((v & 0x02) << 1) | ((v & 0x01) << 3);
+}
+
+static inline unsigned bitswap5(unsigned v)
+{
+	return ((v & 0x10) >> 4) | ((v & 0x08) >> 2) | ((v & 0x04) >> 0) |
+		((v & 0x02) << 2) | ((v & 0x01) << 4);
+}
+
+static inline unsigned bitswap6(unsigned v)
+{
+	return ((v & 0x20) >> 5) | ((v & 0x10) >> 3) | ((v & 0x08) >> 1) |
+		((v & 0x04) << 1) | ((v & 0x02) << 3) | ((v & 0x01) << 5);
+}
+
+static unsigned bitswap(unsigned v, unsigned n)
+{
+	switch (n) {
+	case 1:
+		return v;
+	case 2:
+		return bitswap2(v);
+	case 3:
+		return bitswap3(v);
+	case 4:
+		return bitswap4(v);
+	case 5:
+		return bitswap5(v);
+	case 6:
+		return bitswap6(v);
+	default:
+		return 0;
+	}
+}
+
+/* Generate non-recursive state output from generator state table
+ * Note that the shift register moves right (i.e. the most recent bit is
+ * shifted into the register at k-1 bit of the register), which is typical
+ * textbook representation. The API transition table expects the most recent
+ * bit in the low order bit, or left shift. A bitswap operation is required
+ * to accommodate the difference.
+ */
+static unsigned gen_output(struct vstate *state, int val,
+	const struct osmo_conv_code *code)
+{
+	unsigned out, prev;
+
+	prev = bitswap(state->prev[0], code->K - 1);
+	out = code->next_output[prev][val];
+	out = bitswap(out, code->N);
+
+	return out;
+}
+
+/* Populate non-recursive trellis state
+ * For a given state defined by the k-1 length shift register, find the
+ * value of the input bit that drove the trellis to that state. Also
+ * generate the N outputs of the generator polynomial at that state.
+ */
+static int gen_state_info(uint8_t *val, unsigned reg,
+	int16_t *output, const struct osmo_conv_code *code)
+{
+	int i;
+	unsigned out;
+	struct vstate state;
+
+	/* Previous '0' state */
+	state.state = reg;
+	state.prev[0] = vstate_lshift(reg, code->K, 0);
+	state.prev[1] = vstate_lshift(reg, code->K, 1);
+
+	*val = (reg >> (code->K - 2)) & 0x01;
+
+	/* Transition output */
+	out = gen_output(&state, *val, code);
+
+	/* Unpack to NRZ */
+	for (i = 0; i < code->N; i++)
+		output[i] = BIT2NRZ(out, i);
+
+	return 0;
+}
+
+/* Generate recursive state output from generator state table */
+static unsigned gen_recursive_output(struct vstate *state,
+	uint8_t *val, unsigned reg,
+	const struct osmo_conv_code *code, int pos)
+{
+	int val0, val1;
+	unsigned out, prev;
+
+	/* Previous '0' state */
+	prev = vstate_lshift(reg, code->K, 0);
+	prev = bitswap(prev, code->K - 1);
+
+	/* Input value */
+	val0 = (reg >> (code->K - 2)) & 0x01;
+	val1 = (code->next_term_output[prev] >> pos) & 0x01;
+	*val = val0 == val1 ? 0 : 1;
+
+	/* Wrapper for osmocom state access */
+	prev = bitswap(state->prev[0], code->K - 1);
+
+	/* Compute the transition output */
+	out = code->next_output[prev][*val];
+	out = bitswap(out, code->N);
+
+	return out;
+}
+
+/* Populate recursive trellis state
+ * The bit position of the systematic bit is not explicitly marked by the
+ * API, so it must be extracted from the generator table. Otherwise,
+ * populate the trellis similar to the non-recursive version.
+ * Non-systematic recursive codes are not supported.
+ */
+static int gen_recursive_state_info(uint8_t *val,
+	unsigned reg, int16_t *output, const struct osmo_conv_code *code)
+{
+	int i, j, pos = -1;
+	int ns = NUM_STATES(code->K);
+	unsigned out;
+	struct vstate state;
+
+	/* Previous '0' and '1' states */
+	state.state = reg;
+	state.prev[0] = vstate_lshift(reg, code->K, 0);
+	state.prev[1] = vstate_lshift(reg, code->K, 1);
+
+	/* Find recursive bit location */
+	for (i = 0; i < code->N; i++) {
+		for (j = 0; j < ns; j++) {
+			if ((code->next_output[j][0] >> i) & 0x01)
+				break;
+		}
+
+		if (j == ns) {
+			pos = i;
+			break;
+		}
+	}
+
+	/* Non-systematic recursive code not supported */
+	if (pos < 0)
+		return -EPROTO;
+
+	/* Transition output */
+	out = gen_recursive_output(&state, val, reg, code, pos);
+
+	/* Unpack to NRZ */
+	for (i = 0; i < code->N; i++)
+		output[i] = BIT2NRZ(out, i);
+
+	return 0;
+}
+
+/* Release the trellis */
+static void free_trellis(struct vtrellis *trellis)
+{
+	if (!trellis)
+		return;
+
+	vdec_free(trellis->outputs);
+	vdec_free(trellis->sums);
+	free(trellis->vals);
+	free(trellis);
+}
+
+/* Allocate and initialize the trellis object
+ * Initialization consists of generating the outputs and output value of a
+ * given state. Due to trellis symmetry and anti-symmetry, only one of the
+ * transition paths is utilized by the butterfly operation in the forward
+ * recursion, so only one set of N outputs is required per state variable.
+ */
+static struct vtrellis *generate_trellis(const struct osmo_conv_code *code)
+{
+	int i, rc = -1;
+	struct vtrellis *trellis;
+	int16_t *outputs;
+
+	int ns = NUM_STATES(code->K);
+	int recursive = conv_code_recursive(code);
+	int olen = (code->N == 2) ? 2 : 4;
+
+	trellis = (struct vtrellis *) calloc(1, sizeof(struct vtrellis));
+	if (!trellis)
+		goto fail;
+
+	trellis->num_states = ns;
+	trellis->sums =	vdec_malloc(ns);
+	trellis->outputs = vdec_malloc(ns * olen);
+	trellis->vals = (uint8_t *) malloc(ns * sizeof(uint8_t));
+
+	if (!trellis->sums || !trellis->outputs || !trellis->vals)
+		goto fail;
+
+	/* Populate the trellis state objects */
+	for (i = 0; i < ns; i++) {
+		outputs = &trellis->outputs[olen * i];
+		if (recursive) {
+			rc = gen_recursive_state_info(&trellis->vals[i],
+				i, outputs, code);
+		} else {
+			rc = gen_state_info(&trellis->vals[i],
+				i, outputs, code);
+		}
+	}
+
+	if (rc < 0)
+		goto fail;
+
+	return trellis;
+
+fail:
+	free_trellis(trellis);
+	return NULL;
+}
+
+/* Reset decoder
+ * Set accumulated path metrics to zero. For termination other than
+ * tail-biting, initialize the zero state as the encoder starting state.
+ * Initialize with the maximum accumulated sum at length equal to the
+ * constraint length.
+ */
+static void reset_decoder(struct vdecoder *dec, int term)
+{
+	int ns = dec->trellis->num_states;
+
+	memset(dec->trellis->sums, 0, sizeof(int16_t) * ns);
+
+	if (term != CONV_TERM_TAIL_BITING)
+		dec->trellis->sums[0] = INT8_MAX * dec->n * dec->k;
+}
+
+static void _traceback(struct vdecoder *dec,
+	unsigned state, uint8_t *out, int len)
+{
+	int i;
+	unsigned path;
+
+	for (i = len - 1; i >= 0; i--) {
+		path = dec->paths[i][state] + 1;
+		out[i] = dec->trellis->vals[state];
+		state = vstate_lshift(state, dec->k, path);
+	}
+}
+
+static void _traceback_rec(struct vdecoder *dec,
+	unsigned state, uint8_t *out, int len)
+{
+	int i;
+	unsigned path;
+
+	for (i = len - 1; i >= 0; i--) {
+		path = dec->paths[i][state] + 1;
+		out[i] = path ^ dec->trellis->vals[state];
+		state = vstate_lshift(state, dec->k, path);
+	}
+}
+
+/* Traceback and generate decoded output
+ * Find the largest accumulated path metric at the final state except for
+ * the zero terminated case, where we assume the final state is always zero.
+ */
+static int traceback(struct vdecoder *dec, uint8_t *out, int term, int len)
+{
+	int i, sum, max = -1;
+	unsigned path, state = 0;
+
+	if (term != CONV_TERM_FLUSH) {
+		for (i = 0; i < dec->trellis->num_states; i++) {
+			sum = dec->trellis->sums[i];
+			if (sum > max) {
+				max = sum;
+				state = i;
+			}
+		}
+
+		if (max < 0)
+			return -EPROTO;
+	}
+
+	for (i = dec->len - 1; i >= len; i--) {
+		path = dec->paths[i][state] + 1;
+		state = vstate_lshift(state, dec->k, path);
+	}
+
+	if (dec->recursive)
+		_traceback_rec(dec, state, out, len);
+	else
+		_traceback(dec, state, out, len);
+
+	return 0;
+}
+
+/* Release decoder object */
+static void free_vdec(struct vdecoder *dec)
+{
+	if (!dec)
+		return;
+
+	free_trellis(dec->trellis);
+
+	if (dec->paths != NULL) {
+		vdec_free(dec->paths[0]);
+		free(dec->paths);
+	}
+
+	free(dec);
+}
+
+/* Allocate decoder object
+ * Subtract the constraint length K on the normalization interval to
+ * accommodate the initialization path metric at state zero.
+ */
+static struct vdecoder *alloc_vdec(const struct osmo_conv_code *code)
+{
+	int i, ns;
+	struct vdecoder *dec;
+
+	ns = NUM_STATES(code->K);
+
+	dec = (struct vdecoder *) calloc(1, sizeof(struct vdecoder));
+	dec->n = code->N;
+	dec->k = code->K;
+	dec->recursive = conv_code_recursive(code);
+	dec->intrvl = INT16_MAX / (dec->n * INT8_MAX) - dec->k;
+
+	if (dec->k == 5) {
+		switch (dec->n) {
+		case 2:
+			dec->metric_func = osmo_conv_metrics_k5_n2;
+			break;
+		case 3:
+			dec->metric_func = osmo_conv_metrics_k5_n3;
+			break;
+		case 4:
+			dec->metric_func = osmo_conv_metrics_k5_n4;
+			break;
+		default:
+			goto fail;
+		}
+	} else if (dec->k == 7) {
+		switch (dec->n) {
+		case 2:
+			dec->metric_func = osmo_conv_metrics_k7_n2;
+			break;
+		case 3:
+			dec->metric_func = osmo_conv_metrics_k7_n3;
+			break;
+		case 4:
+			dec->metric_func = osmo_conv_metrics_k7_n4;
+			break;
+		default:
+			goto fail;
+		}
+	} else {
+		goto fail;
+	}
+
+	if (code->term == CONV_TERM_FLUSH)
+		dec->len = code->len + code->K - 1;
+	else
+		dec->len = code->len;
+
+	dec->trellis = generate_trellis(code);
+	if (!dec->trellis)
+		goto fail;
+
+	dec->paths = (int16_t **) malloc(sizeof(int16_t *) * dec->len);
+	if (!dec->paths)
+		goto fail;
+
+	dec->paths[0] = vdec_malloc(ns * dec->len);
+	if (!dec->paths[0])
+		goto fail;
+
+	for (i = 1; i < dec->len; i++)
+		dec->paths[i] = &dec->paths[0][i * ns];
+
+	return dec;
+
+fail:
+	free_vdec(dec);
+	return NULL;
+}
+
+/* Depuncture sequence with nagative value terminated puncturing matrix */
+static int depuncture(const int8_t *in, const int *punc, int8_t *out, int len)
+{
+	int i, n = 0, m = 0;
+
+	for (i = 0; i < len; i++) {
+		if (i == punc[n]) {
+			out[i] = 0;
+			n++;
+			continue;
+		}
+
+		out[i] = in[m++];
+	}
+
+	return 0;
+}
+
+/* Forward trellis recursion
+ * Generate branch metrics and path metrics with a combined function. Only
+ * accumulated path metric sums and path selections are stored. Normalize on
+ * the interval specified by the decoder.
+ */
+static void forward_traverse(struct vdecoder *dec, const int8_t *seq)
+{
+	struct vtrellis *trellis = dec->trellis;
+	int i;
+
+	for (i = 0; i < dec->len; i++) {
+		dec->metric_func(&seq[dec->n * i],
+			trellis->outputs,
+			trellis->sums,
+			dec->paths[i],
+			!(i % dec->intrvl));
+	}
+}
+
+/* Convolutional decode with a decoder object
+ * Initial puncturing run if necessary followed by the forward recursion.
+ * For tail-biting perform a second pass before running the backward
+ * traceback operation.
+ */
+static int conv_decode(struct vdecoder *dec, const int8_t *seq,
+	const int *punc, uint8_t *out, int len, int term)
+{
+	int8_t depunc[dec->len * dec->n];
+
+	reset_decoder(dec, term);
+
+	if (punc) {
+		depuncture(seq, punc, depunc, dec->len * dec->n);
+		seq = depunc;
+	}
+
+	/* Propagate through the trellis with interval normalization */
+	forward_traverse(dec, seq);
+
+	if (term == CONV_TERM_TAIL_BITING)
+		forward_traverse(dec, seq);
+
+	return traceback(dec, out, term, len);
+}
+
+static void osmo_conv_init(void)
+{
+	init_complete = 1;
+
+#ifdef HAVE___BUILTIN_CPU_SUPPORTS
+	/* Detect CPU capabilities */
+	#ifdef HAVE_AVX2
+		avx2_supported = __builtin_cpu_supports("avx2");
+	#endif
+
+	#ifdef HAVE_SSE3
+		sse3_supported = __builtin_cpu_supports("sse3");
+	#endif
+
+	#ifdef HAVE_SSE4_1
+		sse41_supported = __builtin_cpu_supports("sse4.1");
+	#endif
+#endif
+
+/**
+ * Usage of curly braces is mandatory,
+ * because we use multi-line define.
+ */
+#if defined(HAVE_SSE3) && defined(HAVE_AVX2)
+	if (sse3_supported && avx2_supported) {
+		INIT_POINTERS(sse_avx);
+	} else if (sse3_supported) {
+		INIT_POINTERS(sse);
+	} else {
+		INIT_POINTERS(gen);
+	}
+#elif defined(HAVE_SSE3)
+	if (sse3_supported) {
+		INIT_POINTERS(sse);
+	} else {
+		INIT_POINTERS(gen);
+	}
+#else
+	INIT_POINTERS(gen);
+#endif
+}
+
+/* All-in-one Viterbi decoding  */
+int osmo_conv_decode_acc(const struct osmo_conv_code *code,
+	const sbit_t *input, ubit_t *output)
+{
+	int rc;
+	struct vdecoder *vdec;
+
+	if (!init_complete)
+		osmo_conv_init();
+
+	if ((code->N < 2) || (code->N > 4) || (code->len < 1) ||
+		((code->K != 5) && (code->K != 7)))
+		return -EINVAL;
+
+	vdec = alloc_vdec(code);
+	if (!vdec)
+		return -EFAULT;
+
+	rc = conv_decode(vdec, input, code->puncture,
+		output, code->len, code->term);
+
+	free_vdec(vdec);
+
+	return rc;
+}