![Sean Young](/assets/img/avatar_default.png)
This remote sends a header pulse of 8150us followed by a space of 4000us. Signed-off-by: Sean Young <sean@mess.org> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
228 lines
5.8 KiB
C
228 lines
5.8 KiB
C
/* ir-nec-decoder.c - handle NEC IR Pulse/Space protocol
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*
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* Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/bitrev.h>
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#include <linux/module.h>
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#include "rc-core-priv.h"
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#define NEC_NBITS 32
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#define NEC_UNIT 562500 /* ns */
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#define NEC_HEADER_PULSE (16 * NEC_UNIT)
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#define NECX_HEADER_PULSE (8 * NEC_UNIT) /* Less common NEC variant */
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#define NEC_HEADER_SPACE (8 * NEC_UNIT)
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#define NEC_REPEAT_SPACE (4 * NEC_UNIT)
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#define NEC_BIT_PULSE (1 * NEC_UNIT)
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#define NEC_BIT_0_SPACE (1 * NEC_UNIT)
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#define NEC_BIT_1_SPACE (3 * NEC_UNIT)
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#define NEC_TRAILER_PULSE (1 * NEC_UNIT)
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#define NEC_TRAILER_SPACE (10 * NEC_UNIT) /* even longer in reality */
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#define NECX_REPEAT_BITS 1
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enum nec_state {
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STATE_INACTIVE,
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STATE_HEADER_SPACE,
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STATE_BIT_PULSE,
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STATE_BIT_SPACE,
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STATE_TRAILER_PULSE,
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STATE_TRAILER_SPACE,
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};
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/**
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* ir_nec_decode() - Decode one NEC pulse or space
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* @dev: the struct rc_dev descriptor of the device
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* @duration: the struct ir_raw_event descriptor of the pulse/space
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*
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* This function returns -EINVAL if the pulse violates the state machine
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*/
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static int ir_nec_decode(struct rc_dev *dev, struct ir_raw_event ev)
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{
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struct nec_dec *data = &dev->raw->nec;
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u32 scancode;
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u8 address, not_address, command, not_command;
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bool send_32bits = false;
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if (!(dev->raw->enabled_protocols & RC_TYPE_NEC))
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return 0;
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if (!is_timing_event(ev)) {
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if (ev.reset)
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data->state = STATE_INACTIVE;
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return 0;
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}
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IR_dprintk(2, "NEC decode started at state %d (%uus %s)\n",
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data->state, TO_US(ev.duration), TO_STR(ev.pulse));
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switch (data->state) {
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case STATE_INACTIVE:
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if (!ev.pulse)
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break;
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if (eq_margin(ev.duration, NEC_HEADER_PULSE, NEC_UNIT * 2)) {
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data->is_nec_x = false;
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data->necx_repeat = false;
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} else if (eq_margin(ev.duration, NECX_HEADER_PULSE, NEC_UNIT / 2))
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data->is_nec_x = true;
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else
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break;
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data->count = 0;
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data->state = STATE_HEADER_SPACE;
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return 0;
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case STATE_HEADER_SPACE:
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if (ev.pulse)
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break;
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if (eq_margin(ev.duration, NEC_HEADER_SPACE, NEC_UNIT)) {
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data->state = STATE_BIT_PULSE;
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return 0;
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} else if (eq_margin(ev.duration, NEC_REPEAT_SPACE, NEC_UNIT / 2)) {
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if (!dev->keypressed) {
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IR_dprintk(1, "Discarding last key repeat: event after key up\n");
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} else {
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rc_repeat(dev);
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IR_dprintk(1, "Repeat last key\n");
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data->state = STATE_TRAILER_PULSE;
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}
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return 0;
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}
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break;
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case STATE_BIT_PULSE:
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if (!ev.pulse)
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break;
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if (!eq_margin(ev.duration, NEC_BIT_PULSE, NEC_UNIT / 2))
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break;
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data->state = STATE_BIT_SPACE;
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return 0;
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case STATE_BIT_SPACE:
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if (ev.pulse)
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break;
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if (data->necx_repeat && data->count == NECX_REPEAT_BITS &&
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geq_margin(ev.duration,
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NEC_TRAILER_SPACE, NEC_UNIT / 2)) {
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IR_dprintk(1, "Repeat last key\n");
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rc_repeat(dev);
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data->state = STATE_INACTIVE;
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return 0;
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} else if (data->count > NECX_REPEAT_BITS)
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data->necx_repeat = false;
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data->bits <<= 1;
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if (eq_margin(ev.duration, NEC_BIT_1_SPACE, NEC_UNIT / 2))
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data->bits |= 1;
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else if (!eq_margin(ev.duration, NEC_BIT_0_SPACE, NEC_UNIT / 2))
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break;
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data->count++;
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if (data->count == NEC_NBITS)
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data->state = STATE_TRAILER_PULSE;
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else
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data->state = STATE_BIT_PULSE;
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return 0;
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case STATE_TRAILER_PULSE:
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if (!ev.pulse)
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break;
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if (!eq_margin(ev.duration, NEC_TRAILER_PULSE, NEC_UNIT / 2))
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break;
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data->state = STATE_TRAILER_SPACE;
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return 0;
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case STATE_TRAILER_SPACE:
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if (ev.pulse)
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break;
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if (!geq_margin(ev.duration, NEC_TRAILER_SPACE, NEC_UNIT / 2))
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break;
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address = bitrev8((data->bits >> 24) & 0xff);
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not_address = bitrev8((data->bits >> 16) & 0xff);
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command = bitrev8((data->bits >> 8) & 0xff);
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not_command = bitrev8((data->bits >> 0) & 0xff);
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if ((command ^ not_command) != 0xff) {
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IR_dprintk(1, "NEC checksum error: received 0x%08x\n",
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data->bits);
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send_32bits = true;
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}
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if (send_32bits) {
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/* NEC transport, but modified protocol, used by at
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* least Apple and TiVo remotes */
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scancode = data->bits;
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IR_dprintk(1, "NEC (modified) scancode 0x%08x\n", scancode);
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} else if ((address ^ not_address) != 0xff) {
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/* Extended NEC */
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scancode = address << 16 |
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not_address << 8 |
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command;
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IR_dprintk(1, "NEC (Ext) scancode 0x%06x\n", scancode);
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} else {
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/* Normal NEC */
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scancode = address << 8 | command;
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IR_dprintk(1, "NEC scancode 0x%04x\n", scancode);
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}
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if (data->is_nec_x)
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data->necx_repeat = true;
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rc_keydown(dev, scancode, 0);
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data->state = STATE_INACTIVE;
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return 0;
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}
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IR_dprintk(1, "NEC decode failed at count %d state %d (%uus %s)\n",
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data->count, data->state, TO_US(ev.duration), TO_STR(ev.pulse));
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data->state = STATE_INACTIVE;
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return -EINVAL;
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}
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static struct ir_raw_handler nec_handler = {
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.protocols = RC_TYPE_NEC,
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.decode = ir_nec_decode,
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};
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static int __init ir_nec_decode_init(void)
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{
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ir_raw_handler_register(&nec_handler);
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printk(KERN_INFO "IR NEC protocol handler initialized\n");
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return 0;
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}
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static void __exit ir_nec_decode_exit(void)
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{
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ir_raw_handler_unregister(&nec_handler);
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}
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module_init(ir_nec_decode_init);
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module_exit(ir_nec_decode_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@redhat.com>");
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MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
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MODULE_DESCRIPTION("NEC IR protocol decoder");
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