added no aggregation for no activity, buffer memory swapping

.gitignore

@@ -1,2 +1,3 @@
 obj_*
 *~
+code.pdf

Coursework-Reports/code.lyx

@@ -0,0 +1,197 @@
+#LyX 2.3 created this file. For more info see http://www.lyx.org/
+\lyxformat 544
+\begin_document
+\begin_header
+\save_transient_properties true
+\origin unavailable
+\textclass article
+\begin_preamble
+\usepackage{color}
+
+\definecolor{commentgreen}{RGB}{0,94,11}
+\end_preamble
+\use_default_options true
+\begin_modules
+customHeadersFooters
+\end_modules
+\maintain_unincluded_children false
+\language english
+\language_package default
+\inputencoding auto
+\fontencoding global
+\font_roman "default" "default"
+\font_sans "default" "default"
+\font_typewriter "default" "default"
+\font_math "auto" "auto"
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+\font_sf_scale 100 100
+\font_tt_scale 100 100
+\use_microtype false
+\use_dash_ligatures true
+\graphics default
+\default_output_format default
+\output_sync 0
+\bibtex_command default
+\index_command default
+\paperfontsize default
+\spacing single
+\use_hyperref true
+\pdf_title "IoT Aggregation Algorithm Coursework"
+\pdf_author "Andy Pack"
+\pdf_subject "IoT"
+\pdf_bookmarks true
+\pdf_bookmarksnumbered false
+\pdf_bookmarksopen false
+\pdf_bookmarksopenlevel 1
+\pdf_breaklinks true
+\pdf_pdfborder true
+\pdf_colorlinks false
+\pdf_backref false
+\pdf_pdfusetitle true
+\papersize default
+\use_geometry true
+\use_package amsmath 1
+\use_package amssymb 1
+\use_package cancel 1
+\use_package esint 1
+\use_package mathdots 1
+\use_package mathtools 1
+\use_package mhchem 1
+\use_package stackrel 1
+\use_package stmaryrd 1
+\use_package undertilde 1
+\cite_engine basic
+\cite_engine_type default
+\biblio_style plain
+\use_bibtopic false
+\use_indices false
+\paperorientation portrait
+\suppress_date false
+\justification true
+\use_refstyle 1
+\use_minted 0
+\index Index
+\shortcut idx
+\color #008000
+\end_index
+\leftmargin 1cm
+\topmargin 1.5cm
+\rightmargin 1cm
+\bottommargin 1.5cm
+\secnumdepth 3
+\tocdepth 3
+\paragraph_separation indent
+\paragraph_indentation default
+\is_math_indent 0
+\math_numbering_side default
+\quotes_style english
+\dynamic_quotes 0
+\papercolumns 1
+\papersides 1
+\paperpagestyle fancy
+\tracking_changes false
+\output_changes false
+\html_math_output 0
+\html_css_as_file 0
+\html_be_strict false
+\end_header
+
+\begin_body
+
+\begin_layout Left Header
+IoT Aggregation Algorithm Coursework
+\end_layout
+
+\begin_layout Left Footer
+November 2020
+\end_layout
+
+\begin_layout Right Footer
+Andy Pack / 6420013
+\end_layout
+
+\begin_layout Standard
+\begin_inset CommandInset toc
+LatexCommand lstlistoflistings
+
+\end_inset
+
+
+\begin_inset CommandInset include
+LatexCommand lstinputlisting
+filename "../Coursework/coursework.c"
+lstparams "breaklines=true,frame=tb,language=C,basicstyle={\\ttfamily},commentstyle={\\color{commentgreen}\\itshape},keywordstyle={\\color{blue}},emphstyle={\\color{red}},stringstyle={\\color{red}},identifierstyle={\\color{cyan}},caption={Main coursework program: 2 processes for reading and aggregating data}"
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+\begin_inset Newpage pagebreak
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+\begin_inset CommandInset include
+LatexCommand lstinputlisting
+filename "../Coursework/buffer.h"
+lstparams "breaklines=true,frame=tb,language=C,basicstyle={\\ttfamily},commentstyle={\\color{commentgreen}\\itshape},keywordstyle={\\color{blue}},emphstyle={\\color{red}},stringstyle={\\color{red}},identifierstyle={\\color{cyan}},caption={Buffer header file: get, free and manipulate buffers}"
+
+\end_inset
+
+
+\begin_inset Newpage pagebreak
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+\begin_inset CommandInset include
+LatexCommand lstinputlisting
+filename "../Coursework/math.h"
+lstparams "breaklines=true,frame=tb,language=C,basicstyle={\\ttfamily},commentstyle={\\color{commentgreen}\\itshape},keywordstyle={\\color{blue}},emphstyle={\\color{red}},stringstyle={\\color{red}},identifierstyle={\\color{cyan}},caption={Math header file: mean, standard deviation, implementations of ceil, sqrt}"
+
+\end_inset
+
+
+\begin_inset Newpage pagebreak
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+\begin_inset CommandInset include
+LatexCommand lstinputlisting
+filename "../Coursework/io.h"
+lstparams "breaklines=true,frame=tb,language=C,basicstyle={\\ttfamily},commentstyle={\\color{commentgreen}\\itshape},keywordstyle={\\color{blue}},emphstyle={\\color{red}},stringstyle={\\color{red}},identifierstyle={\\color{cyan}},caption={IO header file: init function for starting sensors}"
+
+\end_inset
+
+
+\begin_inset Newpage pagebreak
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+\begin_inset CommandInset include
+LatexCommand lstinputlisting
+filename "../Coursework/util.h"
+lstparams "breaklines=true,frame=tb,language=C,basicstyle={\\ttfamily},commentstyle={\\color{commentgreen}\\itshape},keywordstyle={\\color{blue}},emphstyle={\\color{red}},stringstyle={\\color{red}},identifierstyle={\\color{cyan}},caption={Other utilities: short and float printing functions from earlier labs}"
+
+\end_inset
+
+
+\end_layout
+
+\end_body
+\end_document

Coursework/buffer.h

@@ -11,7 +11,7 @@ typedef struct Buffer {
 } Buffer;
 
 Buffer
-getBuffer(int size)
+getBuffer(int size) // retrieve new buffer with malloc-ed memory space
 {
     float* memSpace = (float*) malloc(size * sizeof(float));
     Buffer buffer = {memSpace, size, };
@@ -19,12 +19,30 @@ getBuffer(int size)
 }
 
 void
+freeBuffer(Buffer buffer) // little abstraction function to act as buffer destructor
+{
+    free(buffer.items);
+}
+
+void
+swapBufferMemory(Buffer *first, Buffer *second) // swap memspaces between buffers
+{
+    float* firstItems = first->items; // swap input buffer and output buffer item pointers
+    first->items = second->items;
+    second->items = firstItems;
+    
+    int firstLength = first->length; // swap lengths to iterate correctly
+    first->length = second->length;
+    second->length = firstLength;
+}
+
+void // perform aggregation into groupSize (4 in the spec) 
 aggregateBuffer(Buffer bufferIn, Buffer bufferOut, int groupSize)
 {
     int requiredGroups = ceil((float)bufferIn.length/groupSize); // number of groups
-    int finalGroupSize = (bufferIn.length % groupSize) * groupSize;
+    int finalGroupSize = (bufferIn.length % groupSize) * groupSize; // work out length of final group if bufferIn not of length that divides nicely
 
-    if(requiredGroups > bufferOut.length) // error
+    if(requiredGroups > bufferOut.length) // error check
     {
         putFloat((float)bufferIn.length/groupSize);
         printf(" length out buffer required, %i provided\n", bufferOut.length);
@@ -39,9 +57,9 @@ aggregateBuffer(Buffer bufferIn, Buffer bufferOut, int groupSize)
         int length = groupSize; // length of this group's size
         if(g == requiredGroups - 1 && finalGroupSize != 0) length = finalGroupSize; // shorten if necessary
         
-        *outputPtr = calculateMean(inputPtr, length); // SET
+        *outputPtr = calculateMean(inputPtr, length); // SET OUTPUT VALUE
         
-        inputPtr += length; // increment both
+        inputPtr += length; // increment both cursors
         outputPtr++;
     }
 }

Coursework/cooja_coursework.csc

@@ -64,8 +64,8 @@
     <width>321</width>
     <z>0</z>
     <height>160</height>
-    <location_x>48</location_x>
-    <location_y>710</location_y>
+    <location_x>51</location_x>
+    <location_y>875</location_y>
   </plugin>
   <plugin>
     se.sics.cooja.plugins.Visualizer
@@ -74,7 +74,7 @@
       <viewport>0.9090909090909091 0.0 0.0 0.9090909090909091 153.72871631902638 172.41033658502872</viewport>
     </plugin_config>
     <width>314</width>
-    <z>5</z>
+    <z>6</z>
     <height>179</height>
     <location_x>40</location_x>
     <location_y>20</location_y>
@@ -90,7 +90,7 @@
       <zoomfactor>500.0</zoomfactor>
     </plugin_config>
     <width>1217</width>
-    <z>4</z>
+    <z>5</z>
     <height>183</height>
     <location_x>424</location_x>
     <location_y>852</location_y>
@@ -102,7 +102,7 @@
       <decorations>true</decorations>
     </plugin_config>
     <width>6</width>
-    <z>6</z>
+    <z>7</z>
     <height>160</height>
     <location_x>680</location_x>
     <location_y>0</location_y>
@@ -127,11 +127,11 @@
       <interface>Temperature and Light</interface>
       <scrollpos>0,0</scrollpos>
     </plugin_config>
-    <width>397</width>
+    <width>340</width>
     <z>1</z>
     <height>179</height>
-    <location_x>2</location_x>
-    <location_y>247</location_y>
+    <location_x>28</location_x>
+    <location_y>227</location_y>
   </plugin>
   <plugin>
     se.sics.cooja.plugins.MoteInterfaceViewer
@@ -141,10 +141,23 @@
       <scrollpos>0,0</scrollpos>
     </plugin_config>
     <width>317</width>
-    <z>2</z>
+    <z>4</z>
     <height>206</height>
     <location_x>28</location_x>
     <location_y>445</location_y>
   </plugin>
+  <plugin>
+    se.sics.cooja.plugins.MoteInterfaceViewer
+    <mote_arg>0</mote_arg>
+    <plugin_config>
+      <interface>Button</interface>
+      <scrollpos>0,0</scrollpos>
+    </plugin_config>
+    <width>296</width>
+    <z>2</z>
+    <height>115</height>
+    <location_x>54</location_x>
+    <location_y>699</location_y>
+  </plugin>
 </simconf>
 

Coursework/coursework.c

@@ -1,12 +1,17 @@
-#define READING_INTERVAL 3 //in Hz
-#define BUFFER_SIZE 9 // length of buffer to populate
+#define READING_INTERVAL 2 //in Hz
+#define BUFFER_SIZE 12 // length of buffer to populate
 
-#define SD_THRESHOLD 300 // whether to aggregate or flatten
-#define AGGREGATION_GROUP_SIZE 3 // group size to aggregate (4 in spec)
+#define SD_THRESHOLD_SOME 400 // some activity, compress above, flatten below
+#define SD_THRESHOLD_LOTS 1000 // lots of activity, don't aggregate
+
+#define AGGREGATION_GROUP_SIZE 4 // group size to aggregate (4 in spec)
+
+#define INITIAL_STATE true // whether begins running or not
 
 #include "contiki.h"
 
 #include <stdio.h> /* For printf() */
+#include <stdbool.h>
 
 #include "io.h"
 #include "util.h" // for print methods
@@ -16,51 +21,73 @@
 static process_event_t event_buffer_full;
 
 /*---------------------------------------------------------------------------*/
-PROCESS(sensing_process, "Sensing process");
-PROCESS(aggregator_process, "Aggregator process");
+PROCESS(sensing_process, "Sensing process"); // collect data
+PROCESS(aggregator_process, "Aggregator process"); // receive full data buffers for processing
 
 AUTOSTART_PROCESSES(&sensing_process, &aggregator_process);
 /*---------------------------------------------------------------------------*/
 PROCESS_THREAD(sensing_process, ev, data)
 {
     /*INIT*/
-    static struct etimer timer;
     PROCESS_BEGIN();
-    event_buffer_full = process_alloc_event();
+    
+    static struct etimer timer;
     etimer_set(&timer, CLOCK_SECOND/READING_INTERVAL);
     
-    SENSORS_ACTIVATE(light_sensor);
-    leds_off(LEDS_ALL);
+    event_buffer_full = process_alloc_event();
+    
+    initIO();
+    
+    static bool isRunning = INITIAL_STATE;
     
     static Buffer buffer;
     buffer = getBuffer(BUFFER_SIZE);
-    clearBuffer(buffer);
-    printBuffer(buffer);putchar('\n');putchar('\n');
     /*END INIT*/
     
     static int counter = 0;
     while(1)
     {
-        PROCESS_WAIT_EVENT_UNTIL(ev == PROCESS_EVENT_TIMER);
+        PROCESS_WAIT_EVENT();
+        
+        if (ev == PROCESS_EVENT_TIMER){
+            if (isRunning == true) {
                 leds_off(LEDS_RED);
                 
                 float light_lx = getLight(); // GET
 
                 buffer.items[counter] = light_lx; // STORE
                 
-        printf("%2i/%i: ", counter + 1, buffer.length);putFloat(light_lx);putchar('\n'); // DISPLAY VALUE
-        //printBuffer(buffer, BUFFER_SIZE);putchar('\n'); // DISPLAY CURRENT BUFFER
+                printf("%2i/%i: ", counter + 1, buffer.length);putFloat(light_lx);putchar('\n'); // DISPLAY CURRENT VALUE
+                //printBuffer(buffer);putchar('\n'); // DISPLAY CURRENT BUFFER
                 
                 counter++;
                 if(counter == buffer.length) // CHECK WHETHER FULL
                 {                
-            process_post(&aggregator_process, event_buffer_full, &buffer);
+                    process_post(&aggregator_process, event_buffer_full, &buffer); // pass buffer to processing thread
                     counter = 0;
-            buffer = getBuffer(BUFFER_SIZE);
+                    buffer = getBuffer(BUFFER_SIZE); // get new buffer for next data, no freeing in this thread
+                }
             }
             
             etimer_reset(&timer);
         }
+        /* BUTTON CLICKED */
+        else if (ev == sensors_event && data == &button_sensor)
+        {
+            isRunning = !isRunning;
+            if (isRunning == true)
+            {
+                printf("Starting...\n");
+            }
+            else
+            {
+                printf("Stopping, clearing buffer...\n");
+                //freeBuffer(buffer);
+                //buffer = getBuffer(BUFFER_SIZE);
+                counter = 0; // just reset counter, used as index on buffer items, will overwrite
+            }
+        }
+    }
 
     PROCESS_END();
 }
@@ -76,8 +103,8 @@ PROCESS_THREAD(aggregator_process, ev, data)
 
         Buffer fullBuffer = *(Buffer *)data;
         /*********************/
-        handleBufferRotation(fullBuffer);
-        free(fullBuffer.items);
+        handleBufferRotation(&fullBuffer); // pass by reference, edited if lots of activity
+        freeBuffer(fullBuffer);
         /*********************/
     }
 
@@ -86,26 +113,41 @@ PROCESS_THREAD(aggregator_process, ev, data)
 /*---------------------------------------------------------------------------*/
 // Buffer filled with readings, process and aggregate
 void
-handleBufferRotation(Buffer inBuffer)
+handleBufferRotation(Buffer *inBufferPtr)
 {
     printf("Buffer full, aggregating\n\n");
     
+    Buffer inBuffer = *inBufferPtr;
     Buffer outBuffer; // OUTPUT BUFFER HOLDER
     // above pointer is assigned a buffer in either of the below cases
 
     Stats sd = calculateStdDev(inBuffer.items, inBuffer.length); // GET BUFFER STATISTICS
-    if(sd.std > SD_THRESHOLD)
-    {// buffer length by 4
-        printf("Significant STD: ");putFloat(sd.std);printf(", compressing buffer\n");
+    
+    /* LOTS OF ACTIVITY - LEAVE */
+    if(sd.std > SD_THRESHOLD_LOTS)
+    {
+        printf("Lots of activity, std. dev.: ");putFloat(sd.std);printf(", leaving as-is\n");
+        
+        outBuffer = getBuffer(1); // get a dummy buffer, will swap items for efficiency
+        
+        swapBufferMemory(inBufferPtr, &outBuffer); // ensures both are freed but no need to copy items
+        
+    }
+    /* SOME ACTIVITY - AGGREGATE */
+    else if(sd.std > SD_THRESHOLD_SOME)
+    {
+        printf("Some activity, std. dev.: ");putFloat(sd.std);printf(", compressing buffer\n");
         
         int outLength = ceil((float)inBuffer.length/AGGREGATION_GROUP_SIZE); // CALCULATE NUMBER OF OUTPUT ELEMENTS
         outBuffer = getBuffer(outLength); // CREATE OUTPUT BUFFER
     
         aggregateBuffer(inBuffer, outBuffer, AGGREGATION_GROUP_SIZE);
 
-    }else
-    {// buffer length to 1
-        printf("Insignificant STD: ");putFloat(sd.std);printf(", squashing buffer\n");
+    }
+    /* NO ACTIVITY - FLATTEN */
+    else
+    {
+        printf("Insignificant std. dev.: ");putFloat(sd.std);printf(", squashing buffer\n");
         
         outBuffer = getBuffer(1); // CREATE OUTPUT BUFFER
         outBuffer.items[0] = sd.mean;
@@ -114,7 +156,7 @@ handleBufferRotation(Buffer inBuffer)
     
     /*********************/
     handleFinalBuffer(outBuffer); // PASS FINAL BUFFER
-    free(outBuffer.items); // RELEASE ITEMS
+    freeBuffer(outBuffer); // RELEASE ITEMS
     /*********************/
 }
 

Coursework/io.h

@@ -2,8 +2,17 @@
 #define _IO_GUARD
 
 #include "dev/light-sensor.h"
+#include "dev/button-sensor.h"
 #include "dev/leds.h"
 
+void 
+initIO()
+{
+    SENSORS_ACTIVATE(light_sensor);
+    SENSORS_ACTIVATE(button_sensor);
+    leds_off(LEDS_ALL);
+}
+
 // get float from light sensor including transfer function
 float
 getLight(void)

Coursework/math.h

@@ -37,6 +37,7 @@ calculateMean(float buffer[], int length)
         return 0;
     }
     
+    /* SUM */
     float sum = 0;
     int i;
     for(i = 0; i < length; i++)
@@ -44,7 +45,7 @@ calculateMean(float buffer[], int length)
         sum += buffer[i];
     }
     
-    return sum / length;
+    return sum / length; // DIVIDE ON RETURN
 }
 
 Stats
@@ -63,8 +64,8 @@ calculateStdDev(float buffer[], int length)
     int i;
     for(i = 0; i < length; i++)
     {
-        float diffFromMean = buffer[i] - stats.mean;
-        sum += diffFromMean*diffFromMean;
+        float diffFromMean = buffer[i] - stats.mean; // (xi - mu)
+        sum += diffFromMean*diffFromMean; // Sum(diff squared)
     }
     
     stats.std = sqrt(sum/length);