make it so

README.md

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+# morse
+
+Morse Code through CPU utilization.
+
+## Usage
+
+The API exposes two simple functions, `dit` and `dah`. `dit` will utilize the
+CPU for a second, `dah` will sleep. Knowing this, we can exchange information
+by looking at the program’s CPU utilization every second. A simple POC is
+included in `main.c` and `observe.sh`. It’s really, really crude. For best
+results, compile without optimizations.
+
+<hr/>
+
+Have fun!

main.c

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+#include "morse.h"
+
+int main() {
+  dit();
+  dah();
+  dit();
+  dit();
+  dah();
+  dit();
+  return 0;
+}

observe.sh

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+PID=$1
+RET=0
+
+while [ "$RET" == 0 ]; do
+  INP=`ps -o pcpu -p $PID`
+  RET=$?
+  ARR=($INP)
+  echo ${ARR[1]}
+  if [ `echo "${ARR[1]}"'>'50 | bc -l` == 1 ]; then
+    echo dit
+  else
+    echo dah
+  fi
+  sleep 1
+done

src/morse.c

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+#include "morse.h"
+
+void dit() {
+  time_t t0, t1;
+  time(&t0);
+  t1 = t0;
+
+  while(difftime(t1, t0) < 1) time(&t1);
+}
+
+void dah() {
+  sleep(1);
+}

src/morse.h

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+#include <time.h>
+#include <unistd.h>
+
+void dit();
+void dah();