add initial code to test floating point context switch

test/basics/qthread_fp.c

@@ -0,0 +1,70 @@
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <qthread/qthread.h>
+
+
+// https://www.geeksforgeeks.org/comparison-float-value-c/
+// https://dotnettutorials.net/lesson/taylor-series-using-recursion-in-c/
+// https://www.studytonight.com/c/programs/important-concepts/sum-of-taylor-series
+
+struct parts
+{
+  int length;
+  float exp;
+  float ans;
+  aligned_t* cond;
+};
+
+// https://www.w3resource.com/c-programming-exercises/math/c-math-exercise-24.php
+static float taylor_exponential_core(int n, float x)
+{
+  float exp_sum = 1;
+  for (int i = n - 1; i > 0; --i)
+  {
+    exp_sum = 1 + x * exp_sum / i;
+  }
+  return exp_sum;
+}
+
+static aligned_t taylor_exponential(void *arg)
+{
+  struct parts* te = (struct parts*) arg;
+  float exp = te->exp;
+  float length = te->length;
+  te->ans = taylor_exponential_core(te->length, te->exp);
+  return 0;
+}
+
+static void checkFloat()
+{
+  void* cond = malloc(QTHREAD_SIZEOF_ALIGNED_T);
+  struct parts teParts = {250,9.0f,0.0f, cond};
+  int ret = -1;
+  qthread_empty(teParts.cond);
+
+  ret = qthread_fork(taylor_exponential, &teParts, teParts.cond);
+  assert(ret == QTHREAD_SUCCESS);
+
+  ret = qthread_readFF(NULL, teParts.cond);
+  assert(ret == QTHREAD_SUCCESS);
+
+  printf("value of ans = %f\n", teParts.ans);
+}
+
+int main(void)
+{
+  float ans = taylor_exponential_core(250, 9.0);
+  printf("value of ans = %f\n", ans);
+  assert(ans == 8103.083984f);
+
+  int status = qthread_initialize();
+  assert(status == QTHREAD_SUCCESS);
+
+  checkFloat();
+  return EXIT_SUCCESS;
+}