1 files changed, 129 insertions, 0 deletions
diff --git a/nuttx/arch/x86/src/common/up_udelay.c b/nuttx/arch/x86/src/common/up_udelay.c
new file mode 100644
index 000000000..92d3b7c16
--- /dev/null
+++ b/nuttx/arch/x86/src/common/up_udelay.c
@@ -0,0 +1,129 @@
+/****************************************************************************
+ *  arch/x86/src/common/up_udelay.c
+ *
+ *   Copyright (C) 2011 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <nuttx/arch.h>
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+#define CONFIG_BOARD_LOOPSPER100USEC ((CONFIG_BOARD_LOOPSPERMSEC+5)/10)
+#define CONFIG_BOARD_LOOPSPER10USEC  ((CONFIG_BOARD_LOOPSPERMSEC+50)/100)
+#define CONFIG_BOARD_LOOPSPERUSEC    ((CONFIG_BOARD_LOOPSPERMSEC+500)/1000)
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_udelay
+ *
+ * Description:
+ *   Delay inline for the requested number of microseconds.  NOTE:  Because
+ *   of all of the setup, several microseconds will be lost before the actual
+ *   timing looop begins.  Thus, the delay will always be a few microseconds
+ *   longer than requested.
+ *
+ *   *** NOT multi-tasking friendly ***
+ *
+ * ASSUMPTIONS:
+ *   The setting CONFIG_BOARD_LOOPSPERMSEC has been calibrated
+ *
+ ****************************************************************************/
+
+void up_udelay(useconds_t microseconds)
+{
+  volatile int i;
+
+  /* We'll do this a little at a time because we expect that the
+   * CONFIG_BOARD_LOOPSPERUSEC is very inaccurate during to truncation in
+   * the divisions of its calculation.  We'll use the largest values that
+   * we can in order to prevent significant error buildup in the loops.
+   */
+
+  while (microseconds > 1000)
+    {
+      for (i = 0; i < CONFIG_BOARD_LOOPSPERMSEC; i++)
+        {
+        }
+      microseconds -= 1000;
+    }
+
+  while (microseconds > 100)
+    {
+      for (i = 0; i < CONFIG_BOARD_LOOPSPER100USEC; i++)
+        {
+        }
+      microseconds -= 100;
+    }
+
+  while (microseconds > 10)
+    {
+      for (i = 0; i < CONFIG_BOARD_LOOPSPER10USEC; i++)
+        {
+        }
+      microseconds -= 10;
+    }
+
+  while (microseconds > 0)
+    {
+      for (i = 0; i < CONFIG_BOARD_LOOPSPERUSEC; i++)
+        {
+        }
+      microseconds--;
+    }
+}