From 090d8a264d52dd03b66511cba413819ed2316ea8 Mon Sep 17 00:00:00 2001
From: root <root@artemis.panaceas.org>
Date: Tue, 6 Sep 2016 14:29:07 +0100
Subject: fish

---
 app/ticker.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 app/ticker.c

diff --git a/app/ticker.c b/app/ticker.c
new file mode 100644
index 0000000..efcbda6
--- /dev/null
+++ b/app/ticker.c
@@ -0,0 +1,86 @@
+#include "project.h"
+
+
+static volatile uint32_t delay_ms_count;
+volatile uint32_t ticks;
+static uint32_t scale = 7;
+
+void
+delay_us (uint32_t d)
+{
+  d *= scale;
+  while (d--)
+    {
+      __asm__ ("nop");
+    }
+}
+
+
+void
+sys_tick_handler (void)
+{
+  uint8_t d;
+
+  if (delay_ms_count)
+    delay_ms_count--;
+
+  ticks++;
+
+  while (!ring_read_byte (&rx1_ring, &d))
+    kvm_recv (d);
+
+  while (!ring_read_byte (&rx2_ring, &d))
+    kvm_recv (d);
+
+  led_tick ();
+}
+
+
+void
+delay_ms (uint32_t d)
+{
+  delay_ms_count = d;
+  while (delay_ms_count);
+}
+
+int
+timed_out (uint32_t then, unsigned int ms)
+{
+  then = ticks - then;
+
+  if (then > ms)
+    return 1;
+  return 0;
+}
+
+
+void
+ticker_init (void)
+{
+  uint32_t v, w;
+
+  /*Start periodic timer */
+
+  systick_set_clocksource (STK_CSR_CLKSOURCE_AHB_DIV8);
+  /* 48MHz / 8 = > 6Mhz */
+  systick_set_reload (6000);
+  /* 6MHz / 6000 => 1kHz */
+  systick_interrupt_enable ();
+  systick_counter_enable ();
+
+
+  /*Calibrate the delay loop */
+  do
+    {
+      scale--;
+      v = ticks;
+      while (v == ticks);
+      delay_us (1000);
+      w = ticks;
+      v++;
+      w -= v;
+    }
+  while (w);
+
+
+}
-- 
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