ir-jvc-decoder.c
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/* ir-jvc-decoder.c - handle JVC IR Pulse/Space protocol
*
* Copyright (C) 2010 by David Härdeman <david@hardeman.nu>
*
* 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 <linux/bitrev.h>
#include <linux/module.h>
#include "rc-core-priv.h"
#define JVC_NBITS 16 /* dev(8) + func(8) */
#define JVC_UNIT 525000 /* ns */
#define JVC_HEADER_PULSE (16 * JVC_UNIT) /* lack of header -> repeat */
#define JVC_HEADER_SPACE (8 * JVC_UNIT)
#define JVC_BIT_PULSE (1 * JVC_UNIT)
#define JVC_BIT_0_SPACE (1 * JVC_UNIT)
#define JVC_BIT_1_SPACE (3 * JVC_UNIT)
#define JVC_TRAILER_PULSE (1 * JVC_UNIT)
#define JVC_TRAILER_SPACE (35 * JVC_UNIT)
enum jvc_state {
STATE_INACTIVE,
STATE_HEADER_SPACE,
STATE_BIT_PULSE,
STATE_BIT_SPACE,
STATE_TRAILER_PULSE,
STATE_TRAILER_SPACE,
STATE_CHECK_REPEAT,
};
/**
* ir_jvc_decode() - Decode one JVC pulse or space
* @dev: the struct rc_dev descriptor of the device
* @duration: the struct ir_raw_event descriptor of the pulse/space
*
* This function returns -EINVAL if the pulse violates the state machine
*/
static int ir_jvc_decode(struct rc_dev *dev, struct ir_raw_event ev)
{
struct jvc_dec *data = &dev->raw->jvc;
if (!(dev->enabled_protocols & RC_BIT_JVC))
return 0;
if (!is_timing_event(ev)) {
if (ev.reset)
data->state = STATE_INACTIVE;
return 0;
}
if (!geq_margin(ev.duration, JVC_UNIT, JVC_UNIT / 2))
goto out;
IR_dprintk(2, "JVC decode started at state %d (%uus %s)\n",
data->state, TO_US(ev.duration), TO_STR(ev.pulse));
again:
switch (data->state) {
case STATE_INACTIVE:
if (!ev.pulse)
break;
if (!eq_margin(ev.duration, JVC_HEADER_PULSE, JVC_UNIT / 2))
break;
data->count = 0;
data->first = true;
data->toggle = !data->toggle;
data->state = STATE_HEADER_SPACE;
return 0;
case STATE_HEADER_SPACE:
if (ev.pulse)
break;
if (!eq_margin(ev.duration, JVC_HEADER_SPACE, JVC_UNIT / 2))
break;
data->state = STATE_BIT_PULSE;
return 0;
case STATE_BIT_PULSE:
if (!ev.pulse)
break;
if (!eq_margin(ev.duration, JVC_BIT_PULSE, JVC_UNIT / 2))
break;
data->state = STATE_BIT_SPACE;
return 0;
case STATE_BIT_SPACE:
if (ev.pulse)
break;
data->bits <<= 1;
if (eq_margin(ev.duration, JVC_BIT_1_SPACE, JVC_UNIT / 2)) {
data->bits |= 1;
decrease_duration(&ev, JVC_BIT_1_SPACE);
} else if (eq_margin(ev.duration, JVC_BIT_0_SPACE, JVC_UNIT / 2))
decrease_duration(&ev, JVC_BIT_0_SPACE);
else
break;
data->count++;
if (data->count == JVC_NBITS)
data->state = STATE_TRAILER_PULSE;
else
data->state = STATE_BIT_PULSE;
return 0;
case STATE_TRAILER_PULSE:
if (!ev.pulse)
break;
if (!eq_margin(ev.duration, JVC_TRAILER_PULSE, JVC_UNIT / 2))
break;
data->state = STATE_TRAILER_SPACE;
return 0;
case STATE_TRAILER_SPACE:
if (ev.pulse)
break;
if (!geq_margin(ev.duration, JVC_TRAILER_SPACE, JVC_UNIT / 2))
break;
if (data->first) {
u32 scancode;
scancode = (bitrev8((data->bits >> 8) & 0xff) << 8) |
(bitrev8((data->bits >> 0) & 0xff) << 0);
IR_dprintk(1, "JVC scancode 0x%04x\n", scancode);
rc_keydown(dev, scancode, data->toggle);
data->first = false;
data->old_bits = data->bits;
} else if (data->bits == data->old_bits) {
IR_dprintk(1, "JVC repeat\n");
rc_repeat(dev);
} else {
IR_dprintk(1, "JVC invalid repeat msg\n");
break;
}
data->count = 0;
data->state = STATE_CHECK_REPEAT;
return 0;
case STATE_CHECK_REPEAT:
if (!ev.pulse)
break;
if (eq_margin(ev.duration, JVC_HEADER_PULSE, JVC_UNIT / 2))
data->state = STATE_INACTIVE;
else
data->state = STATE_BIT_PULSE;
goto again;
}
out:
IR_dprintk(1, "JVC decode failed at state %d (%uus %s)\n",
data->state, TO_US(ev.duration), TO_STR(ev.pulse));
data->state = STATE_INACTIVE;
return -EINVAL;
}
static struct ir_raw_handler jvc_handler = {
.protocols = RC_BIT_JVC,
.decode = ir_jvc_decode,
};
static int __init ir_jvc_decode_init(void)
{
ir_raw_handler_register(&jvc_handler);
printk(KERN_INFO "IR JVC protocol handler initialized\n");
return 0;
}
static void __exit ir_jvc_decode_exit(void)
{
ir_raw_handler_unregister(&jvc_handler);
}
module_init(ir_jvc_decode_init);
module_exit(ir_jvc_decode_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
MODULE_DESCRIPTION("JVC IR protocol decoder");