Release 4.16 drivers/media/rc/ir-nec-decoder.c
// SPDX-License-Identifier: GPL-2.0
// ir-nec-decoder.c - handle NEC IR Pulse/Space protocol
//
// Copyright (C) 2010 by Mauro Carvalho Chehab
#include <linux/bitrev.h>
#include <linux/module.h>
#include "rc-core-priv.h"
#define NEC_NBITS 32
#define NEC_UNIT 562500
/* ns */
#define NEC_HEADER_PULSE (16 * NEC_UNIT)
#define NECX_HEADER_PULSE (8 * NEC_UNIT)
/* Less common NEC variant */
#define NEC_HEADER_SPACE (8 * NEC_UNIT)
#define NEC_REPEAT_SPACE (4 * NEC_UNIT)
#define NEC_BIT_PULSE (1 * NEC_UNIT)
#define NEC_BIT_0_SPACE (1 * NEC_UNIT)
#define NEC_BIT_1_SPACE (3 * NEC_UNIT)
#define NEC_TRAILER_PULSE (1 * NEC_UNIT)
#define NEC_TRAILER_SPACE (10 * NEC_UNIT)
/* even longer in reality */
#define NECX_REPEAT_BITS 1
enum nec_state {
STATE_INACTIVE,
STATE_HEADER_SPACE,
STATE_BIT_PULSE,
STATE_BIT_SPACE,
STATE_TRAILER_PULSE,
STATE_TRAILER_SPACE,
};
/**
* ir_nec_decode() - Decode one NEC pulse or space
* @dev: the struct rc_dev descriptor of the device
* @ev: the struct ir_raw_event descriptor of the pulse/space
*
* This function returns -EINVAL if the pulse violates the state machine
*/
static int ir_nec_decode(struct rc_dev *dev, struct ir_raw_event ev)
{
struct nec_dec *data = &dev->raw->nec;
u32 scancode;
enum rc_proto rc_proto;
u8 address, not_address, command, not_command;
if (!is_timing_event(ev)) {
if (ev.reset)
data->state = STATE_INACTIVE;
return 0;
}
IR_dprintk(2, "NEC decode started at state %d (%uus %s)\n",
data->state, TO_US(ev.duration), TO_STR(ev.pulse));
switch (data->state) {
case STATE_INACTIVE:
if (!ev.pulse)
break;
if (eq_margin(ev.duration, NEC_HEADER_PULSE, NEC_UNIT * 2)) {
data->is_nec_x = false;
data->necx_repeat = false;
} else if (eq_margin(ev.duration, NECX_HEADER_PULSE, NEC_UNIT / 2))
data->is_nec_x = true;
else
break;
data->count = 0;
data->state = STATE_HEADER_SPACE;
return 0;
case STATE_HEADER_SPACE:
if (ev.pulse)
break;
if (eq_margin(ev.duration, NEC_HEADER_SPACE, NEC_UNIT)) {
data->state = STATE_BIT_PULSE;
return 0;
} else if (eq_margin(ev.duration, NEC_REPEAT_SPACE, NEC_UNIT / 2)) {
data->state = STATE_TRAILER_PULSE;
return 0;
}
break;
case STATE_BIT_PULSE:
if (!ev.pulse)
break;
if (!eq_margin(ev.duration, NEC_BIT_PULSE, NEC_UNIT / 2))
break;
data->state = STATE_BIT_SPACE;
return 0;
case STATE_BIT_SPACE:
if (ev.pulse)
break;
if (data->necx_repeat && data->count == NECX_REPEAT_BITS &&
geq_margin(ev.duration,
NEC_TRAILER_SPACE, NEC_UNIT / 2)) {
IR_dprintk(1, "Repeat last key\n");
rc_repeat(dev);
data->state = STATE_INACTIVE;
return 0;
} else if (data->count > NECX_REPEAT_BITS)
data->necx_repeat = false;
data->bits <<= 1;
if (eq_margin(ev.duration, NEC_BIT_1_SPACE, NEC_UNIT / 2))
data->bits |= 1;
else if (!eq_margin(ev.duration, NEC_BIT_0_SPACE, NEC_UNIT / 2))
break;
data->count++;
if (data->count == NEC_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, NEC_TRAILER_PULSE, NEC_UNIT / 2))
break;
data->state = STATE_TRAILER_SPACE;
return 0;
case STATE_TRAILER_SPACE:
if (ev.pulse)
break;
if (!geq_margin(ev.duration, NEC_TRAILER_SPACE, NEC_UNIT / 2))
break;
if (data->count == NEC_NBITS) {
address = bitrev8((data->bits >> 24) & 0xff);
not_address = bitrev8((data->bits >> 16) & 0xff);
command = bitrev8((data->bits >> 8) & 0xff);
not_command = bitrev8((data->bits >> 0) & 0xff);
scancode = ir_nec_bytes_to_scancode(address,
not_address,
command,
not_command,
&rc_proto);
if (data->is_nec_x)
data->necx_repeat = true;
rc_keydown(dev, rc_proto, scancode, 0);
} else {
rc_repeat(dev);
}
data->state = STATE_INACTIVE;
return 0;
}
IR_dprintk(1, "NEC decode failed at count %d state %d (%uus %s)\n",
data->count, data->state, TO_US(ev.duration), TO_STR(ev.pulse));
data->state = STATE_INACTIVE;
return -EINVAL;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| David Härdeman | 328 | 50.08% | 7 | 30.43% |
| Mauro Carvalho Chehab | 188 | 28.70% | 8 | 34.78% |
| Maxim Levitsky | 105 | 16.03% | 2 | 8.70% |
| Sean Young | 26 | 3.97% | 4 | 17.39% |
| Shawn Guo | 5 | 0.76% | 1 | 4.35% |
| Jarod Wilson | 3 | 0.46% | 1 | 4.35% |
| Total | 655 | 100.00% | 23 | 100.00% |
/**
* ir_nec_scancode_to_raw() - encode an NEC scancode ready for modulation.
* @protocol: specific protocol to use
* @scancode: a single NEC scancode.
*/
static u32 ir_nec_scancode_to_raw(enum rc_proto protocol, u32 scancode)
{
unsigned int addr, addr_inv, data, data_inv;
data = scancode & 0xff;
if (protocol == RC_PROTO_NEC32) {
/* 32-bit NEC (used by Apple and TiVo remotes) */
/* scan encoding: aaAAddDD */
addr_inv = (scancode >> 24) & 0xff;
addr = (scancode >> 16) & 0xff;
data_inv = (scancode >> 8) & 0xff;
} else if (protocol == RC_PROTO_NECX) {
/* Extended NEC */
/* scan encoding AAaaDD */
addr = (scancode >> 16) & 0xff;
addr_inv = (scancode >> 8) & 0xff;
data_inv = data ^ 0xff;
} else {
/* Normal NEC */
/* scan encoding: AADD */
addr = (scancode >> 8) & 0xff;
addr_inv = addr ^ 0xff;
data_inv = data ^ 0xff;
}
/* raw encoding: ddDDaaAA */
return data_inv << 24 |
data << 16 |
addr_inv << 8 |
addr;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| James Hogan | 146 | 97.99% | 1 | 50.00% |
| Sean Young | 3 | 2.01% | 1 | 50.00% |
| Total | 149 | 100.00% | 2 | 100.00% |
static const struct ir_raw_timings_pd ir_nec_timings = {
.header_pulse = NEC_HEADER_PULSE,
.header_space = NEC_HEADER_SPACE,
.bit_pulse = NEC_BIT_PULSE,
.bit_space[0] = NEC_BIT_0_SPACE,
.bit_space[1] = NEC_BIT_1_SPACE,
.trailer_pulse = NEC_TRAILER_PULSE,
.trailer_space = NEC_TRAILER_SPACE,
.msb_first = 0,
};
/**
* ir_nec_encode() - Encode a scancode as a stream of raw events
*
* @protocol: protocol to encode
* @scancode: scancode to encode
* @events: array of raw ir events to write into
* @max: maximum size of @events
*
* Returns: The number of events written.
* -ENOBUFS if there isn't enough space in the array to fit the
* encoding. In this case all @max events will have been written.
*/
static int ir_nec_encode(enum rc_proto protocol, u32 scancode,
struct ir_raw_event *events, unsigned int max)
{
struct ir_raw_event *e = events;
int ret;
u32 raw;
/* Convert a NEC scancode to raw NEC data */
raw = ir_nec_scancode_to_raw(protocol, scancode);
/* Modulate the raw data using a pulse distance modulation */
ret = ir_raw_gen_pd(&e, max, &ir_nec_timings, NEC_NBITS, raw);
if (ret < 0)
return ret;
return e - events;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| James Hogan | 76 | 98.70% | 1 | 50.00% |
| Sean Young | 1 | 1.30% | 1 | 50.00% |
| Total | 77 | 100.00% | 2 | 100.00% |
static struct ir_raw_handler nec_handler = {
.protocols = RC_PROTO_BIT_NEC | RC_PROTO_BIT_NECX |
RC_PROTO_BIT_NEC32,
.decode = ir_nec_decode,
.encode = ir_nec_encode,
.carrier = 38000,
};
static int __init ir_nec_decode_init(void)
{
ir_raw_handler_register(&nec_handler);
printk(KERN_INFO "IR NEC protocol handler initialized\n");
return 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Mauro Carvalho Chehab | 24 | 100.00% | 1 | 100.00% |
| Total | 24 | 100.00% | 1 | 100.00% |
static void __exit ir_nec_decode_exit(void)
{
ir_raw_handler_unregister(&nec_handler);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Mauro Carvalho Chehab | 15 | 100.00% | 1 | 100.00% |
| Total | 15 | 100.00% | 1 | 100.00% |
module_init(ir_nec_decode_init);
module_exit(ir_nec_decode_exit);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Mauro Carvalho Chehab");
MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
MODULE_DESCRIPTION("NEC IR protocol decoder");
Overall Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| David Härdeman | 363 | 32.47% | 8 | 22.86% |
| Mauro Carvalho Chehab | 314 | 28.09% | 15 | 42.86% |
| James Hogan | 282 | 25.22% | 1 | 2.86% |
| Maxim Levitsky | 110 | 9.84% | 3 | 8.57% |
| Sean Young | 40 | 3.58% | 5 | 14.29% |
| Shawn Guo | 5 | 0.45% | 1 | 2.86% |
| Jarod Wilson | 3 | 0.27% | 1 | 2.86% |
| Paul Gortmaker | 1 | 0.09% | 1 | 2.86% |
| Total | 1118 | 100.00% | 35 | 100.00% |
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