[PATCH] libosmocore[master]: core/conv/conv_acc.c: use static allocation for trellis

[Vadim Yanitskiy]

Hello Jenkins Builder,

I'd like you to reexamine a change.  Please visit

    https://gerrit.osmocom.org/2969

to look at the new patch set (#2).

core/conv/conv_acc.c: use static allocation for trellis

Allocation of a new memory is an expensive operation, which
takes place when it's initially unknown, how much memory will
we need, or in order to decrease total memory usage.

The trellis struct wasn't require dynamic allocation itself,
so let's allocate one statically inside the vdecoder structure.

Change-Id: Ib8e448823ca5548a05a45824b0b1c06743dfe5a4
---
M src/conv_acc.c
1 file changed, 23 insertions(+), 27 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/69/2969/2

diff --git a/src/conv_acc.c b/src/conv_acc.c
index f45d50f..13b220b 100644
--- a/src/conv_acc.c
+++ b/src/conv_acc.c
@@ -164,7 +164,7 @@
 	int len;
 	int recursive;
 	int intrvl;
-	struct vtrellis *trellis;
+	struct vtrellis trellis;
 	int16_t **paths;
 
 	void (*metric_func)(const int8_t *, const int16_t *,
@@ -372,41 +372,38 @@
 	vdec_free(trellis->outputs);
 	vdec_free(trellis->sums);
 	free(trellis->vals);
-	free(trellis);
 }
 
-/* Allocate and initialize the trellis object
+/* 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)
+static int generate_trellis(struct vdecoder *dec,
+	const struct osmo_conv_code *code)
 {
-	int i, rc = -1;
-	struct vtrellis *trellis;
+	struct vtrellis *trellis = &dec->trellis;
 	int16_t *outputs;
+	int i, rc;
 
 	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)
+	if (!trellis->sums || !trellis->outputs || !trellis->vals) {
+		rc = -ENOMEM;
 		goto fail;
+	}
 
 	/* Populate the trellis state objects */
 	for (i = 0; i < ns; i++) {
 		outputs = &trellis->outputs[olen * i];
-		if (recursive) {
+		if (dec->recursive) {
 			rc = gen_recursive_state_info(&trellis->vals[i],
 				i, outputs, code);
 		} else {
@@ -429,11 +426,11 @@
 	if (code->term != CONV_TERM_TAIL_BITING)
 		trellis->sums[0] = INT8_MAX * code->N * code->K;
 
-	return trellis;
+	return 0;
 
 fail:
 	free_trellis(trellis);
-	return NULL;
+	return rc;
 }
 
 static void _traceback(struct vdecoder *dec,
@@ -444,7 +441,7 @@
 
 	for (i = len - 1; i >= 0; i--) {
 		path = dec->paths[i][state] + 1;
-		out[i] = dec->trellis->vals[state];
+		out[i] = dec->trellis.vals[state];
 		state = vstate_lshift(state, dec->k, path);
 	}
 }
@@ -457,7 +454,7 @@
 
 	for (i = len - 1; i >= 0; i--) {
 		path = dec->paths[i][state] + 1;
-		out[i] = path ^ dec->trellis->vals[state];
+		out[i] = path ^ dec->trellis.vals[state];
 		state = vstate_lshift(state, dec->k, path);
 	}
 }
@@ -472,8 +469,8 @@
 	unsigned path, state = 0;
 
 	if (term != CONV_TERM_FLUSH) {
-		for (i = 0; i < dec->trellis->num_states; i++) {
-			sum = dec->trellis->sums[i];
+		for (i = 0; i < dec->trellis.num_states; i++) {
+			sum = dec->trellis.sums[i];
 			if (sum > max) {
 				max = sum;
 				state = i;
@@ -503,7 +500,7 @@
 	if (!dec)
 		return;
 
-	free_trellis(dec->trellis);
+	free_trellis(&dec->trellis);
 
 	if (dec->paths != NULL) {
 		vdec_free(dec->paths[0]);
@@ -517,7 +514,7 @@
  */
 static int vdec_init(struct vdecoder *dec, const struct osmo_conv_code *code)
 {
-	int i, ns;
+	int i, ns, rc;
 
 	ns = NUM_STATES(code->K);
 
@@ -563,9 +560,9 @@
 	else
 		dec->len = code->len;
 
-	dec->trellis = generate_trellis(code);
-	if (!dec->trellis)
-		goto enomem;
+	rc = generate_trellis(dec, code);
+	if (rc)
+		return rc;
 
 	dec->paths = (int16_t **) malloc(sizeof(int16_t *) * dec->len);
 	if (!dec->paths)
@@ -610,13 +607,12 @@
  */
 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->trellis.outputs,
+			dec->trellis.sums,
 			dec->paths[i],
 			!(i % dec->intrvl));
 	}

-- 
To view, visit https://gerrit.osmocom.org/2969
To unsubscribe, visit https://gerrit.osmocom.org/settings

Gerrit-MessageType: newpatchset
Gerrit-Change-Id: Ib8e448823ca5548a05a45824b0b1c06743dfe5a4
Gerrit-PatchSet: 2
Gerrit-Project: libosmocore
Gerrit-Branch: master
Gerrit-Owner: Vadim Yanitskiy <axilirator at gmail.com>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: Tom Tsou <tom at tsou.cc>