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/*
* 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
*
* Copyright (C) 2008 by Openmoko, Inc.
* Author: Nelson Castillo <arhuaco@freaks-unidos.net>
* All rights reserved.
*
* This filter is useful to reject samples that are not reliable. We consider
* that a sample is not reliable if it deviates form the Majority.
*
* 1) We collect S samples.
*
* 2) For each dimension:
*
* - We sort the points.
* - Points that are "close enough" are considered to be in the same set.
* - We choose the set with more elements. If more than "threshold"
* points are in this set we use the first and the last point of the set
* to define the valid range for this dimension [min, max], otherwise we
* discard all the points and go to step 1.
*
* 3) We consider the unsorted S samples and try to feed them to the next
* filter in the chain. If one of the points of each sample
* is not in the allowed range for its dimension, we discard the sample.
*
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/sort.h>
#include "ts_filter_group.h"
static void ts_filter_group_clear_internal(struct ts_filter_group *tsfg,
int attempts)
{
tsfg->N = 0;
tsfg->tries_left = attempts;
}
static void ts_filter_group_clear(struct ts_filter *tsf)
{
struct ts_filter_group *tsfg = (struct ts_filter_group *)tsf;
ts_filter_group_clear_internal(tsfg, tsfg->config->attempts);
if (tsf->next) /* chain */
(tsf->next->api->clear)(tsf->next);
}
static struct ts_filter *ts_filter_group_create(struct platform_device *pdev,
void *conf, int count_coords)
{
struct ts_filter_group *tsfg;
int i;
BUG_ON((count_coords < 1) || (count_coords > MAX_TS_FILTER_COORDS));
tsfg = kzalloc(sizeof(struct ts_filter_group), GFP_KERNEL);
if (!tsfg)
return NULL;
tsfg->config = (struct ts_filter_group_configuration *)conf;
tsfg->tsf.count_coords = count_coords;
BUG_ON(tsfg->config->attempts <= 0);
tsfg->samples[0] = kmalloc((2 + count_coords) * sizeof(int) *
tsfg->config->extent, GFP_KERNEL);
if (!tsfg->samples[0]) {
kfree(tsfg);
return NULL;
}
for (i = 1; i < count_coords; ++i)
tsfg->samples[i] = tsfg->samples[0] + i * tsfg->config->extent;
tsfg->sorted_samples = tsfg->samples[0] + count_coords *
tsfg->config->extent;
tsfg->group_size = tsfg->samples[0] + (1 + count_coords) *
tsfg->config->extent;
ts_filter_group_clear_internal(tsfg, tsfg->config->attempts);
printk(KERN_INFO" Created group ts filter len %d depth %d close %d "
"thresh %d\n", tsfg->config->extent, count_coords,
tsfg->config->close_enough, tsfg->config->threshold);
return &tsfg->tsf;
}
static void ts_filter_group_destroy(struct platform_device *pdev,
struct ts_filter *tsf)
{
struct ts_filter_group *tsfg = (struct ts_filter_group *)tsf;
kfree(tsfg->samples[0]); /* first guy has pointer from kmalloc */
kfree(tsf);
}
static void ts_filter_group_scale(struct ts_filter *tsf, int *coords)
{
if (tsf->next)
(tsf->next->api->scale)(tsf->next, coords);
}
static int int_cmp(const void *_a, const void *_b)
{
const int *a = _a;
const int *b = _b;
if (*a > *b)
return 1;
if (*a < *b)
return -1;
return 0;
}
static int ts_filter_group_process(struct ts_filter *tsf, int *coords)
{
struct ts_filter_group *tsfg = (struct ts_filter_group *)tsf;
int n;
int i;
int ret = 0; /* ask for more samples by default */
BUG_ON(tsfg->N >= tsfg->config->extent);
for (n = 0; n < tsf->count_coords; n++)
tsfg->samples[n][tsfg->N] = coords[n];
if (++tsfg->N < tsfg->config->extent)
return 0; /* we meed more samples */
for (n = 0; n < tsfg->tsf.count_coords; n++) {
int *v = tsfg->sorted_samples;
int ngroups = 0;
int best_size;
int best_idx = 0;
int idx = 0;
memcpy(v, tsfg->samples[n], tsfg->N * sizeof(int));
sort(v, tsfg->N, sizeof(int), int_cmp, NULL);
tsfg->group_size[0] = 1;
for (i = 1; i < tsfg->N; ++i) {
if (v[i] - v[i - 1] <= tsfg->config->close_enough)
tsfg->group_size[ngroups]++;
else
tsfg->group_size[++ngroups] = 1;
}
ngroups++;
best_size = tsfg->group_size[0];
for (i = 1; i < ngroups; i++) {
idx += tsfg->group_size[i - 1];
if (best_size < tsfg->group_size[i]) {
best_size = tsfg->group_size[i];
best_idx = idx;
}
}
if (best_size < tsfg->config->threshold) {
/* this set is not good enough for us */
if (--tsfg->tries_left) {
ts_filter_group_clear_internal
(tsfg, tsfg->tries_left);
return 0; /* ask for more samples */
}
return -1; /* we give up */
}
tsfg->range_min[n] = v[best_idx];
tsfg->range_max[n] = v[best_idx + best_size - 1];
}
for (i = 0; i < tsfg->N; ++i) {
int r;
for (n = 0; n < tsfg->tsf.count_coords; ++n) {
coords[n] = tsfg->samples[n][i];
if (coords[n] < tsfg->range_min[n] ||
coords[n] > tsfg->range_max[n])
break;
}
if (n != tsfg->tsf.count_coords) /* sample not OK */
continue;
if (tsf->next) {
r = (tsf->next->api->process)(tsf->next, coords);
if (r) {
ret = r;
break;
}
} else if (i == tsfg->N - 1) {
ret = 1;
}
}
ts_filter_group_clear_internal(tsfg, tsfg->config->attempts);
return ret;
}
struct ts_filter_api ts_filter_group_api = {
.create = ts_filter_group_create,
.destroy = ts_filter_group_destroy,
.clear = ts_filter_group_clear,
.process = ts_filter_group_process,
.scale = ts_filter_group_scale,
};
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