add ringbuffer

src/Makefile

@@ -3,7 +3,7 @@ CC=gcc
 CFLAGS=-Wall
 LDFLAGS=-lwiringPi -lcurl
 
-counter:	counter.o LS7366R.o influx.o
+counter:	counter.o LS7366R.o influx.o ringbuffer.o
 	$(CC) -o $@ $(LDFLAGS) $^
 
 .c.o:

src/counter.c

@@ -2,11 +2,10 @@
 #include <wiringPiSPI.h>
 #include <stdint.h>
 #include <stdio.h>
-#include <pthread.h>
 
 #include "LS7366R.h"
 #include "influx.h"
-
+#include "ringbuffer.h"
 
 const int CTRL_OUT = 16;
 const int INTR_IN  = 19;
@@ -14,28 +13,15 @@ const int SPI_CHAN = 0;
 const int SPI_SPEED = 1000000;
 
 
-uint32_t diff = 0;
-
-pthread_mutex_t counterMutex = PTHREAD_MUTEX_INITIALIZER;
-pthread_mutex_t eventMutex = PTHREAD_MUTEX_INITIALIZER;
-pthread_cond_t eventSignal = PTHREAD_COND_INITIALIZER;
-
-
 void isr() {
   static uint32_t lastCounter = 0;
 
   uint32_t currentCounter = ls7366rReadOTR();
 
-  pthread_mutex_lock(&counterMutex);
-  diff = currentCounter - lastCounter;
-  pthread_mutex_unlock(&counterMutex);
-
-
+  uint32_t diff = currentCounter - lastCounter;
   lastCounter = currentCounter;
-  
-  pthread_mutex_lock(&eventMutex);
-  pthread_cond_signal(&eventSignal);
-  pthread_mutex_unlock(&eventMutex);
+
+  ringbufferPut(diff);
 }
 
 void init() {
@@ -51,21 +37,13 @@ void init() {
 }
 
 int main (void) {
-  uint32_t my_diff = 0;
-
   init();
   ls7366rInit(SPI_CHAN);
 
   while (1) {
-    pthread_mutex_lock(&eventMutex);
-    pthread_cond_wait(&eventSignal, &eventMutex);
-    pthread_mutex_unlock(&eventMutex);
-
-    pthread_mutex_lock(&counterMutex);
-    my_diff = diff;
-    pthread_mutex_unlock(&counterMutex);
-
-    double f = 1.0 / (((double) my_diff) / 1000000.0);
+    uint32_t diff = ringbufferGet();
+  
+    double f = 1.0 / (((double) diff) / 1000000.0);
     printf("%f\n", f);
     influxSendFrequency(f);
   }

src/ringbuffer.c

@@ -0,0 +1,53 @@
+#include <stdint.h>
+#include <pthread.h>
+
+
+#define BUFFER_SIZE 256
+
+uint32_t buffer[BUFFER_SIZE+5];
+
+uint16_t bufferReadIdx = 0;
+uint16_t bufferWriteIdx = 0;
+
+pthread_mutex_t eventMutex = PTHREAD_MUTEX_INITIALIZER;
+pthread_cond_t eventSignal = PTHREAD_COND_INITIALIZER;
+
+
+  
+
+void ringbufferPut(uint32_t f) {
+    if (bufferWriteIdx == (BUFFER_SIZE - 1)) {
+        while (bufferReadIdx == BUFFER_SIZE);
+    } else {
+        while (bufferReadIdx == (bufferWriteIdx + 1));
+    }
+
+    buffer[bufferWriteIdx] = f;
+    bufferWriteIdx++;
+
+    if (bufferWriteIdx > BUFFER_SIZE) {
+        bufferWriteIdx = 0;
+    }
+
+    pthread_mutex_lock(&eventMutex);
+    pthread_cond_signal(&eventSignal);
+    pthread_mutex_unlock(&eventMutex);
+}
+
+
+uint32_t ringbufferGet() {
+    if (bufferReadIdx == bufferWriteIdx) {
+        pthread_mutex_lock(&eventMutex);
+        pthread_cond_wait(&eventSignal, &eventMutex);
+        pthread_mutex_unlock(&eventMutex);
+    }
+
+	double res = buffer[bufferReadIdx];
+    bufferReadIdx++;
+	if (bufferReadIdx > BUFFER_SIZE) {
+	    bufferReadIdx = 0;
+	}
+    return res;
+}
+
+

src/ringbuffer.h

@@ -0,0 +1,9 @@
+#ifndef _RINGBUFFER_H_
+#define _RINGBUFFER_H_
+
+#include <stdint.h>
+
+void ringbufferPut(uint32_t f);
+uint32_t ringbufferGet();
+
+#endif // _RINGBUFFER_H_