ir-jvc-decoder.c

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/* ir-jvc-decoder.c - handle JVC IR Pulse/Space protocol
 *
 * Copyright (C) 2010 by David Härdeman <[email protected]>
 *
 * 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,
};

static int ir_jvc_decode(struct rc_dev *dev, struct ir_raw_event ev)
{
    struct jvc_dec *data = &dev->raw->jvc;

    if (!(dev->raw->enabled_protocols & RC_TYPE_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_TYPE_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 <[email protected]>");
MODULE_DESCRIPTION("JVC IR protocol decoder");