diff options
Diffstat (limited to 'drivers/media/IR/ir-nec-decoder.c')
-rw-r--r-- | drivers/media/IR/ir-nec-decoder.c | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/drivers/media/IR/ir-nec-decoder.c b/drivers/media/IR/ir-nec-decoder.c new file mode 100644 index 000000000000..16360eb4055b --- /dev/null +++ b/drivers/media/IR/ir-nec-decoder.c @@ -0,0 +1,131 @@ +/* ir-raw-event.c - handle IR Pulse/Space event + * + * Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com> + * + * 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 <media/ir-core.h> + +/* Start time: 4.5 ms */ +#define MIN_START_TIME 3900000 +#define MAX_START_TIME 5100000 + +/* Pulse time: 560 us */ +#define MIN_PULSE_TIME 460000 +#define MAX_PULSE_TIME 660000 + +/* Bit 1 space time: 2.25ms-560 us */ +#define MIN_BIT1_TIME 1490000 +#define MAX_BIT1_TIME 1890000 + +/* Bit 0 space time: 1.12ms-560 us */ +#define MIN_BIT0_TIME 360000 +#define MAX_BIT0_TIME 760000 + + +/** Decode NEC pulsecode. This code can take up to 76.5 ms to run. + Unfortunately, using IRQ to decode pulse didn't work, since it uses + a pulse train of 38KHz. This means one pulse on each 52 us +*/ + +int ir_nec_decode(struct input_dev *input_dev, + struct ir_raw_event *evs, + int len) +{ + int i, count = -1; + int ircode = 0, not_code = 0; +#if 0 + /* Needed only after porting the event code to the decoder */ + struct ir_input_dev *ir = input_get_drvdata(input_dev); +#endif + + /* Be sure that the first event is an start one and is a pulse */ + for (i = 0; i < len; i++) { + if (evs[i].type & (IR_START_EVENT | IR_PULSE)) + break; + } + i++; /* First event doesn't contain data */ + + if (i >= len) + return 0; + + /* First space should have 4.5 ms otherwise is not NEC protocol */ + if ((evs[i].delta.tv_nsec < MIN_START_TIME) | + (evs[i].delta.tv_nsec > MAX_START_TIME) | + (evs[i].type != IR_SPACE)) + goto err; + + /* + * FIXME: need to implement the repeat sequence + */ + + count = 0; + for (i++; i < len; i++) { + int bit; + + if ((evs[i].delta.tv_nsec < MIN_PULSE_TIME) | + (evs[i].delta.tv_nsec > MAX_PULSE_TIME) | + (evs[i].type != IR_PULSE)) + goto err; + + if (++i >= len) + goto err; + if (evs[i].type != IR_SPACE) + goto err; + + if ((evs[i].delta.tv_nsec > MIN_BIT1_TIME) && + (evs[i].delta.tv_nsec < MAX_BIT1_TIME)) + bit = 1; + else if ((evs[i].delta.tv_nsec > MIN_BIT0_TIME) && + (evs[i].delta.tv_nsec < MAX_BIT0_TIME)) + bit = 0; + else + goto err; + + if (bit) { + int shift = count; + /* Address first, then command */ + if (shift < 8) { + shift += 8; + ircode |= 1 << shift; + } else if (shift < 16) { + not_code |= 1 << shift; + } else if (shift < 24) { + shift -= 16; + ircode |= 1 << shift; + } else { + shift -= 24; + not_code |= 1 << shift; + } + } + if (++count == 32) + break; + } + + /* + * Fixme: may need to accept Extended NEC protocol? + */ + if ((ircode & ~not_code) != ircode) { + IR_dprintk(1, "NEC checksum error: code 0x%04x, not-code 0x%04x\n", + ircode, not_code); + return -EINVAL; + } + + IR_dprintk(1, "NEC scancode 0x%04x\n", ircode); + + return ircode; +err: + IR_dprintk(1, "NEC decoded failed at bit %d while decoding %luus time\n", + count, (evs[i].delta.tv_nsec + 500) / 1000); + + return -EINVAL; +} +EXPORT_SYMBOL_GPL(ir_nec_decode); |