Remove noise from the NEC reading function

The comparisons were long-winded and repetitive, so I made a macro to
make them more concise.  Also, all the NEC timing macros now have names
starting with NEC_.

src/main.c

 /*
  * NEC timing macros
  */
-#define DELTA          5
-#define START_PULSE    45
-#define END_PULSE      405
-#define RPT_CMD_PULSE  959
-#define ZERO_PULSE     6
-#define ONE_PULSE      17
-#define COMMA_PULSE    23
+#define NEC_START_PULSE 45
+#define NEC_END_PULSE 405
+#define NEC_RPT_CMD_PULSE 959
+#define NEC_ZERO_PULSE 6
+#define NEC_ONE_PULSE 17
+#define NEC_COMMA_PULSE 23
+
+/* Tolerance */
+#define NEC_DELTA 5
+#define CLOSE_TO(var, target, error) (((var) > ((target) - (error))) && ((var) < ((target) + (error))))
 
 
 static event_listener_t el;
     static uint32_t tmp;
 
     icucnt_t cnt = icuGetWidthX(icup);
-    if ((cnt > (START_PULSE - DELTA)) && (cnt < (START_PULSE + DELTA))) {
+    if (CLOSE_TO(cnt, NEC_START_PULSE, NEC_DELTA)) {
         index = 0;
         START_OCCURED = true;
-    } else if ((cnt > (ONE_PULSE - DELTA)) && (cnt < (ONE_PULSE + DELTA))) {
+    } else if (CLOSE_TO(cnt, NEC_ONE_PULSE, NEC_DELTA)) {
         tmp |= 1 << (31 - index);
         index++;
-    } else if ((cnt > (ZERO_PULSE - DELTA)) && (cnt < (ZERO_PULSE + DELTA))) {
+    } else if (CLOSE_TO(cnt, NEC_ZERO_PULSE, NEC_DELTA)) {
         tmp &= ~(1 << (31 - index));
         index++;
-    } else if ((cnt > (END_PULSE - 4*DELTA)) && (cnt < (END_PULSE + 4*DELTA))) {
+    } else if (CLOSE_TO(cnt, NEC_END_PULSE, 4*NEC_DELTA)) {
         if ((START_OCCURED) && (index == 32)) {
             nec_addr = (tmp >> 24) & 0xFF;
             nec_data = (tmp >> 8) & 0xFF;
         nec_repeat = false;
         START_OCCURED = false;
         index = -1;
-    } else if ((cnt > (RPT_CMD_PULSE - DELTA)) && (cnt < (RPT_CMD_PULSE + DELTA))) {
+    } else if (CLOSE_TO(cnt, NEC_RPT_CMD_PULSE, NEC_DELTA)) {
         nec_repeat = true;
-    } else if ((cnt > (COMMA_PULSE - DELTA)) && (cnt < (COMMA_PULSE + DELTA))) {
+    } else if (CLOSE_TO(cnt, NEC_COMMA_PULSE, NEC_DELTA)) {
         chEvtBroadcastFlags(&IR_receiver, 0);
-    } else {
-        /* Long dead pulse nothing to do */
     }
 }