1 files changed, 120 insertions, 0 deletions
diff --git a/stacks/lwip_stack/release/lwip_helper_files/lwip/arch/win_minmax.h b/stacks/lwip_stack/release/lwip_helper_files/lwip/arch/win_minmax.h
new file mode 100644
index 0000000..e1e64ac
--- /dev/null
+++ b/stacks/lwip_stack/release/lwip_helper_files/lwip/arch/win_minmax.h
@@ -0,0 +1,120 @@
+/**
+ * lib/minmax.c: windowed min/max tracker by Kathleen Nichols.
+ *
+ */
+#ifndef MINMAX_H
+#define MINMAX_H
+
+#include  "types.h"
+#include "rtp_branch_prediction.h"
+
+/* A single data point for our parameterized min-max tracker */
+struct minmax_sample
+{
+  u32_t t;                      /* time measurement was taken */
+  u32_t v;                      /* value measured */
+};
+
+/* State for the parameterized min-max tracker */
+struct minmax
+{
+  struct minmax_sample s[3];
+};
+
+static inline u32_t
+minmax_get (const struct minmax *m)
+{
+  return m->s[0].v;
+}
+
+static inline u32_t
+minmax_reset (struct minmax *m, u32_t t, u32_t meas)
+{
+  struct minmax_sample val = {.t = t,.v = meas };
+
+  m->s[2] = m->s[1] = m->s[0] = val;
+  return m->s[0].v;
+}
+
+/* As time advances, update the 1st, 2nd, and 3rd choices. */
+static u32_t
+minmax_subwin_update (struct minmax *m, u32_t win,
+                      const struct minmax_sample *val)
+{
+  u32_t dt = val->t - m->s[0].t;
+
+  if (unlikely (dt > win))
+    {
+      /*
+       * Passed entire window without a new val so make 2nd
+       * choice the new val & 3rd choice the new 2nd choice.
+       * we may have to iterate this since our 2nd choice
+       * may also be outside the window (we checked on entry
+       * that the third choice was in the window).
+       */
+      m->s[0] = m->s[1];
+      m->s[1] = m->s[2];
+      m->s[2] = *val;
+      if (unlikely (val->t - m->s[0].t > win))
+        {
+          m->s[0] = m->s[1];
+          m->s[1] = m->s[2];
+          m->s[2] = *val;
+        }
+    }
+  else if (unlikely (m->s[1].t == m->s[0].t) && dt > win / 4)
+    {
+      /*
+       * We've passed a quarter of the window without a new val
+       * so take a 2nd choice from the 2nd quarter of the window.
+       */
+      m->s[2] = m->s[1] = *val;
+    }
+  else if (unlikely (m->s[2].t == m->s[1].t) && dt > win / 2)
+    {
+      /*
+       * We've passed half the window without finding a new val
+       * so take a 3rd choice from the last half of the window
+       */
+      m->s[2] = *val;
+    }
+  return m->s[0].v;
+}
+
+/* Check if new measurement updates the 1st, 2nd or 3rd choice max. */
+static inline u32_t
+minmax_running_max (struct minmax *m, u32_t win, u32_t t, u32_t meas)
+{
+  struct minmax_sample val = {.t = t,.v = meas };
+
+  if (unlikely (val.v >= m->s[0].v) ||  /* found new max? */
+      unlikely (val.t - m->s[2].t > win))       /* nothing left in window? */
+    return minmax_reset (m, t, meas);   /* forget earlier samples */
+
+  if (unlikely (val.v >= m->s[1].v))
+    m->s[2] = m->s[1] = val;
+  else if (unlikely (val.v >= m->s[2].v))
+    m->s[2] = val;
+
+  return minmax_subwin_update (m, win, &val);
+}
+
+/* Check if new measurement updates the 1st, 2nd or 3rd choice min. */
+static inline u32_t
+minmax_running_min (struct minmax *m, u32_t win, u32_t t, u32_t meas)
+{
+  struct minmax_sample val = {.t = t,.v = meas };
+
+  if (unlikely (val.v <= m->s[0].v) ||  /* found new min? */
+      unlikely (val.t - m->s[2].t > win))       /* nothing left in window? */
+    return minmax_reset (m, t, meas);   /* forget earlier samples */
+
+  if (unlikely (val.v <= m->s[1].v))
+    m->s[2] = m->s[1] = val;
+  else if (unlikely (val.v <= m->s[2].v))
+    m->s[2] = val;
+
+  return minmax_subwin_update (m, win, &val);
+}
+
+#endif