From e0dd8a5ad830798bc8082b03b8c42c32fb9660e0 Mon Sep 17 00:00:00 2001
From: Sebastian Huber <sebastian.huber@embedded-brains.de>
Date: Fri, 20 Apr 2018 12:08:42 +0200
Subject: bsps: Move benchmark timer to bsps

This patch is a part of the BSP source reorganization.

Update #3285.
---
 bsps/no_cpu/no_bsp/btimer/btimer.c   | 92 ++++++++++++++++++++++++++++++++++++
 bsps/no_cpu/no_bsp/btimer/timerisr.c | 38 +++++++++++++++
 2 files changed, 130 insertions(+)
 create mode 100644 bsps/no_cpu/no_bsp/btimer/btimer.c
 create mode 100644 bsps/no_cpu/no_bsp/btimer/timerisr.c

(limited to 'bsps/no_cpu/no_bsp')

diff --git a/bsps/no_cpu/no_bsp/btimer/btimer.c b/bsps/no_cpu/no_bsp/btimer/btimer.c
new file mode 100644
index 0000000000..e9b59dc756
--- /dev/null
+++ b/bsps/no_cpu/no_bsp/btimer/btimer.c
@@ -0,0 +1,92 @@
+/*  timer.c
+ *
+ *  This file manages the benchmark timer used by the RTEMS Timing Test
+ *  Suite.  Each measured time period is demarcated by calls to
+ *  benchmark_timer_initialize() and benchmark_timer_read().  benchmark_timer_read() usually returns
+ *  the number of microseconds since benchmark_timer_initialize() exitted.
+ *
+ *  NOTE: It is important that the timer start/stop overhead be
+ *        determined when porting or modifying this code.
+ *
+ *  COPYRIGHT (c) 1989-1999.
+ *  On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.org/license/LICENSE.
+ */
+
+#include <rtems.h>
+#include <rtems/btimer.h>
+#include <bsp.h>
+
+uint32_t         Timer_interrupts;
+bool benchmark_timer_find_average_overhead;
+
+void benchmark_timer_initialize( void )
+{
+
+  /*
+   *  Timer has never overflowed.  This may not be necessary on some
+   *  implemenations of timer but ....
+   */
+
+  Timer_interrupts = 0;
+
+  /*
+   *  Somehow start the timer
+   */
+}
+
+/*
+ *  The following controls the behavior of benchmark_timer_read().
+ *
+ *  AVG_OVEREHAD is the overhead for starting and stopping the timer.  It
+ *  is usually deducted from the number returned.
+ *
+ *  LEAST_VALID is the lowest number this routine should trust.  Numbers
+ *  below this are "noise" and zero is returned.
+ */
+
+#define AVG_OVERHEAD      0  /* It typically takes X.X microseconds */
+                             /* (Y countdowns) to start/stop the timer. */
+                             /* This value is in microseconds. */
+#define LEAST_VALID       1  /* Don't trust a clicks value lower than this */
+
+benchmark_timer_t benchmark_timer_read( void )
+{
+  uint32_t         clicks;
+  uint32_t         total;
+
+  /*
+   *  Read the timer and see how many clicks it has been since we started.
+   */
+
+  clicks = 0;   /* XXX: read some HW here */
+
+  /*
+   *  Total is calculated by taking into account the number of timer overflow
+   *  interrupts since the timer was initialized and clicks since the last
+   *  interrupts.
+   */
+
+  total = clicks * 0;
+
+  if ( benchmark_timer_find_average_overhead == true )
+    return total;          /* in XXX microsecond units */
+  else {
+    if ( total < LEAST_VALID )
+      return 0;            /* below timer resolution */
+  /*
+   *  Somehow convert total into microseconds
+   */
+      return (total - AVG_OVERHEAD);
+    }
+}
+
+void benchmark_timer_disable_subtracting_average_overhead(
+  bool find_flag
+)
+{
+  benchmark_timer_find_average_overhead = find_flag;
+}
diff --git a/bsps/no_cpu/no_bsp/btimer/timerisr.c b/bsps/no_cpu/no_bsp/btimer/timerisr.c
new file mode 100644
index 0000000000..5ca7152a54
--- /dev/null
+++ b/bsps/no_cpu/no_bsp/btimer/timerisr.c
@@ -0,0 +1,38 @@
+/**
+ *  @file
+ *
+ *  If required this ISR is used to bump a count of interval "overflow"
+ *  interrupts which have occurred since the timer was started.  The
+ *  number of overflows is taken into account in the benchmark_timer_read()
+ *  routine if necessary.
+ *
+ *  To reduce overhead this is best to be the "rawest" hardware interupt
+ *  handler you can write.  This should be the only interrupt which can
+ *  occur during the measured time period.
+ *
+ *  @note This file is USUALLY in assembly and is LEAN AND MEAN.
+ *        Any code in this isr is pure overhead which can perturb
+ *        the accuracy of the Timing Test Suite.
+ */
+
+/*
+ *  COPYRIGHT (c) 1989-1999.
+ *  On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.org/license/LICENSE.
+ */
+
+#include <rtems.h>
+#include <rtems/btimer.h>
+
+extern uint32_t         _Timer_interrupts;
+
+void timerisr( void )
+{
+  /*
+   *  _Timer_interrupts += TIMER_BETWEEN_OVERFLOWS  (usually in microseconds)
+   *  return from interrupt
+   */
+}
-- 
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