mirror of https://github.com/joan2937/pigpio
137 lines
2.6 KiB
C
137 lines
2.6 KiB
C
#include <stdlib.h>
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#include <pigpio.h>
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#include "ir_hasher.h"
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/*
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This code forms a hash over the IR pulses generated by an
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IR remote.
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The remote key press is not converted into a code in the manner of
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the lirc module. No attempt is made to decode the type of protocol
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used by the remote. The hash is likely to be unique for different
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keys and different remotes but this is not guaranteed.
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This hashing process works for some remotes/protocols but not for
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others. The only way to find out if it works for one or more of
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your remotes is to try it and see.
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*/
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struct _Pi_Hasher_s
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{
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int gpio;
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Pi_Hasher_CB_t callback;
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int timeout;
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int in_code;
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uint32_t hash_val;
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int edges;
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int t1;
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int t2;
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int t3;
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int t4;
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};
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static uint32_t _hash(uint32_t hv, int old_val, int new_val)
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{
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int val;
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if (new_val < (old_val * 0.60)) val = 13;
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else if (old_val < (new_val * 0.60)) val = 23;
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else val = 2;
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hv ^= val;
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hv *= 16777619; /* FNV_PRIME_32 */
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return hv;
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}
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static void _cb(int gpio, int level, uint32_t tick, void *user)
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{
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Pi_Hasher_t * hasher;
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hasher = user;
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if (level != PI_TIMEOUT)
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{
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if (hasher->in_code == 0)
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{
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hasher->in_code = 1;
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gpioSetWatchdog(gpio, hasher->timeout);
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hasher->hash_val = 2166136261U; /* FNV_BASIS_32 */
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hasher->edges = 1;
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hasher->t1 = 0;
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hasher->t2 = 0;
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hasher->t3 = 0;
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hasher->t4 = tick;
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}
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else
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{
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hasher->edges++;
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hasher->t1 = hasher->t2;
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hasher->t2 = hasher->t3;
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hasher->t3 = hasher->t4;
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hasher->t4 = tick;
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if (hasher->edges > 3)
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{
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hasher->hash_val =
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_hash(hasher->hash_val,
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(hasher->t2)-(hasher->t1),
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(hasher->t4)-(hasher->t3));
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}
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}
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}
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else
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{
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if (hasher->in_code)
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{
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hasher->in_code = 0;
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gpioSetWatchdog(gpio, 0);
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if (hasher->edges > 12) /* Anything less is probably noise. */
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{
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(hasher->callback)(hasher->hash_val);
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}
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}
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}
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}
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Pi_Hasher_t *Pi_Hasher(int gpio, Pi_Hasher_CB_t callback, int timeout)
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{
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Pi_Hasher_t *hasher;
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hasher = malloc(sizeof(Pi_Hasher_t));
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hasher->gpio = gpio;
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hasher->callback = callback;
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hasher->timeout = 5;
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hasher->in_code = 0;
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gpioSetMode(gpio, PI_INPUT);
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gpioSetAlertFuncEx(gpio, _cb, hasher);
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return hasher;
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}
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void Pi_Hasher_cancel(Pi_Hasher_t *hasher)
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{
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if (hasher)
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{
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gpioSetAlertFunc(hasher->gpio, 0);
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free(hasher);
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hasher = NULL;
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}
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}
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