279 lines
6.9 KiB
C
279 lines
6.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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// 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
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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 563 /* us */
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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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* @ev: 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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enum rc_proto rc_proto;
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u8 address, not_address, command, not_command;
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if (!is_timing_event(ev)) {
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if (ev.overflow)
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data->state = STATE_INACTIVE;
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return 0;
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}
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dev_dbg(&dev->dev, "NEC decode started at state %d (%uus %s)\n",
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data->state, 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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data->state = STATE_TRAILER_PULSE;
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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, NEC_TRAILER_SPACE, NEC_UNIT / 2)) {
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dev_dbg(&dev->dev, "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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if (data->count == NEC_NBITS) {
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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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scancode = ir_nec_bytes_to_scancode(address,
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not_address,
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command,
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not_command,
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&rc_proto);
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if (data->is_nec_x)
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data->necx_repeat = true;
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rc_keydown(dev, rc_proto, scancode, 0);
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} else {
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rc_repeat(dev);
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}
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data->state = STATE_INACTIVE;
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return 0;
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}
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dev_dbg(&dev->dev, "NEC decode failed at count %d state %d (%uus %s)\n",
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data->count, data->state, 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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/**
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* ir_nec_scancode_to_raw() - encode an NEC scancode ready for modulation.
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* @protocol: specific protocol to use
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* @scancode: a single NEC scancode.
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*/
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static u32 ir_nec_scancode_to_raw(enum rc_proto protocol, u32 scancode)
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{
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unsigned int addr, addr_inv, data, data_inv;
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data = scancode & 0xff;
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if (protocol == RC_PROTO_NEC32) {
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/* 32-bit NEC (used by Apple and TiVo remotes) */
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/* scan encoding: aaAAddDD */
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addr_inv = (scancode >> 24) & 0xff;
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addr = (scancode >> 16) & 0xff;
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data_inv = (scancode >> 8) & 0xff;
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} else if (protocol == RC_PROTO_NECX) {
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/* Extended NEC */
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/* scan encoding AAaaDD */
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addr = (scancode >> 16) & 0xff;
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addr_inv = (scancode >> 8) & 0xff;
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data_inv = data ^ 0xff;
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} else {
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/* Normal NEC */
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/* scan encoding: AADD */
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addr = (scancode >> 8) & 0xff;
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addr_inv = addr ^ 0xff;
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data_inv = data ^ 0xff;
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}
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/* raw encoding: ddDDaaAA */
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return data_inv << 24 |
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data << 16 |
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addr_inv << 8 |
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addr;
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}
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static const struct ir_raw_timings_pd ir_nec_timings = {
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.header_pulse = NEC_HEADER_PULSE,
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.header_space = NEC_HEADER_SPACE,
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.bit_pulse = NEC_BIT_PULSE,
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.bit_space[0] = NEC_BIT_0_SPACE,
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.bit_space[1] = NEC_BIT_1_SPACE,
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.trailer_pulse = NEC_TRAILER_PULSE,
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.trailer_space = NEC_TRAILER_SPACE,
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.msb_first = 0,
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};
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/**
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* ir_nec_encode() - Encode a scancode as a stream of raw events
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*
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* @protocol: protocol to encode
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* @scancode: scancode to encode
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* @events: array of raw ir events to write into
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* @max: maximum size of @events
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*
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* Returns: The number of events written.
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* -ENOBUFS if there isn't enough space in the array to fit the
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* encoding. In this case all @max events will have been written.
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*/
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static int ir_nec_encode(enum rc_proto protocol, u32 scancode,
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struct ir_raw_event *events, unsigned int max)
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{
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struct ir_raw_event *e = events;
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int ret;
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u32 raw;
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/* Convert a NEC scancode to raw NEC data */
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raw = ir_nec_scancode_to_raw(protocol, scancode);
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/* Modulate the raw data using a pulse distance modulation */
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ret = ir_raw_gen_pd(&e, max, &ir_nec_timings, NEC_NBITS, raw);
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if (ret < 0)
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return ret;
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return e - events;
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}
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static struct ir_raw_handler nec_handler = {
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.protocols = RC_PROTO_BIT_NEC | RC_PROTO_BIT_NECX |
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RC_PROTO_BIT_NEC32,
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.decode = ir_nec_decode,
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.encode = ir_nec_encode,
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.carrier = 38000,
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.min_timeout = NEC_TRAILER_SPACE,
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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 v2");
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MODULE_AUTHOR("Mauro Carvalho Chehab");
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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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