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/* ir-raw-event.c - handle IR Pulse/Space event
*
* Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com>
*
* 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 version 2 of the License.
*
* 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.
*/
#include <media/ir-core.h>
/* Start time: 4.5 ms */
#define MIN_START_TIME 3900000
#define MAX_START_TIME 5100000
/* Pulse time: 560 us */
#define MIN_PULSE_TIME 460000
#define MAX_PULSE_TIME 660000
/* Bit 1 space time: 2.25ms-560 us */
#define MIN_BIT1_TIME 1490000
#define MAX_BIT1_TIME 1890000
/* Bit 0 space time: 1.12ms-560 us */
#define MIN_BIT0_TIME 360000
#define MAX_BIT0_TIME 760000
/** Decode NEC pulsecode. This code can take up to 76.5 ms to run.
Unfortunately, using IRQ to decode pulse didn't work, since it uses
a pulse train of 38KHz. This means one pulse on each 52 us
*/
int ir_nec_decode(struct input_dev *input_dev,
struct ir_raw_event *evs,
int len)
{
int i, count = -1;
int ircode = 0, not_code = 0;
#if 0
/* Needed only after porting the event code to the decoder */
struct ir_input_dev *ir = input_get_drvdata(input_dev);
#endif
/* Be sure that the first event is an start one and is a pulse */
for (i = 0; i < len; i++) {
if (evs[i].type & (IR_START_EVENT | IR_PULSE))
break;
}
i++; /* First event doesn't contain data */
if (i >= len)
return 0;
/* First space should have 4.5 ms otherwise is not NEC protocol */
if ((evs[i].delta.tv_nsec < MIN_START_TIME) |
(evs[i].delta.tv_nsec > MAX_START_TIME) |
(evs[i].type != IR_SPACE))
goto err;
/*
* FIXME: need to implement the repeat sequence
*/
count = 0;
for (i++; i < len; i++) {
int bit;
if ((evs[i].delta.tv_nsec < MIN_PULSE_TIME) |
(evs[i].delta.tv_nsec > MAX_PULSE_TIME) |
(evs[i].type != IR_PULSE))
goto err;
if (++i >= len)
goto err;
if (evs[i].type != IR_SPACE)
goto err;
if ((evs[i].delta.tv_nsec > MIN_BIT1_TIME) &&
(evs[i].delta.tv_nsec < MAX_BIT1_TIME))
bit = 1;
else if ((evs[i].delta.tv_nsec > MIN_BIT0_TIME) &&
(evs[i].delta.tv_nsec < MAX_BIT0_TIME))
bit = 0;
else
goto err;
if (bit) {
int shift = count;
/* Address first, then command */
if (shift < 8) {
shift += 8;
ircode |= 1 << shift;
} else if (shift < 16) {
not_code |= 1 << shift;
} else if (shift < 24) {
shift -= 16;
ircode |= 1 << shift;
} else {
shift -= 24;
not_code |= 1 << shift;
}
}
if (++count == 32)
break;
}
/*
* Fixme: may need to accept Extended NEC protocol?
*/
if ((ircode & ~not_code) != ircode) {
IR_dprintk(1, "NEC checksum error: code 0x%04x, not-code 0x%04x\n",
ircode, not_code);
return -EINVAL;
}
IR_dprintk(1, "NEC scancode 0x%04x\n", ircode);
return ircode;
err:
IR_dprintk(1, "NEC decoded failed at bit %d while decoding %luus time\n",
count, (evs[i].delta.tv_nsec + 500) / 1000);
return -EINVAL;
}
EXPORT_SYMBOL_GPL(ir_nec_decode);
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