Diff: SWO.cpp

Revision:

1:bae4cff278f6

Parent:

0:0fd55660fc26

Child:

2:ef928f61a770

--- a/SWO.cpp	Fri Mar 28 19:32:13 2014 +0000
+++ b/SWO.cpp	Sat Dec 20 22:30:12 2014 +0000
@@ -1,67 +1,86 @@
+/* mbed SWO Library
+ *  Copyright (c) 2014, v01: WH. Ported from Segger example
+ *
+ * Simple implementation for tracing via Single Wire Output(SWO) for Cortex-M processors.
+ * It can be used with Host PC software such as ST-LINK Utility or Segger J-Link SWO viewer.
+ * This sample implementation ensures that output via SWO is enabled in order to guarantee
+ * that the application does not hang.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
 
 #include "SWO.h"
 
-
-/*********************************************************************
-*
-* Defines for Cortex-M debug unit
-*/
+/**
+ *
+ * Defines for Cortex-M debug unit
+ */
 #define ITM_STIM_U32(n) (*(volatile unsigned int*)(0xE0000000+4*n))  // Stimulus Port n Register word access
+#define ITM_STIM_U8(n)  (*(volatile         char*)(0xE0000000+n))    // Stimulus Port n Register byte access
 //#define ITM_STIM_U32_0  (*(volatile unsigned int*)0xE0000000)        // Stimulus Port 0 Register word access
 //#define ITM_STIM_U8_0   (*(volatile         char*)0xE0000000)        // Stimulus Port 0 Register byte access
 #define ITM_ENA         (*(volatile unsigned int*)0xE0000E00)        // Trace Enable Ports Register
 #define ITM_TCR         (*(volatile unsigned int*)0xE0000E80)        // Trace control register
 
-
+/**
+ *
+ * SWO_PrintChar()
+ *
+ * @brief 
+ *   Checks if SWO is set up. If it is not, return,
+ *    to avoid program hangs if no debugger is connected.
+ *   If it is set up, print a character to the ITM_STIM register
+ *    in order to provide data for SWO.
+ * @param c The Character to be printed.
+ * @notes   Additional checks for device specific registers can be added.
+ */
+void SWO_PrintChar(char c) {
 
-/*********************************************************************
-*
-* SWO_PrintChar()
-*
-* @brief 
-*   Checks if SWO is set up. If it is not, return,
-*    to avoid program hangs if no debugger is connected.
-*   If it is set up, print a character to the ITM_STIM register
-*    in order to provide data for SWO.
-* @param c The Character to be printed.
-* @notes   Additional checks for device specific registers can be added.
-*/
-void SWO_PrintChar(char c) {
-  //
   // Check if ITM_TCR.ITMENA is set
-  //
   if ((ITM_TCR & 1) == 0) {
     return;
   }
-  //
+
   // Check if stimulus port is enabled
-  //
   if ((ITM_ENA & 1) == 0) {
     return;
   }
-  //
-  // Wait until STIMx is ready,
-  // then send data
-  //
-//  while ((ITM_STIM_U8(0) & 1) == 0);
-//  ITM_STIM_U8(0) = c;
 
-  while ((ITM_STIM_U32(0) & 1) == 0);
-  ITM_STIM_U32(0) = c;
+  // Wait until STIMx FIFO is ready, then send data
+  while ((ITM_STIM_U8(0) & 1) == 0);
+  ITM_STIM_U8(0) = c;
+
+//  while ((ITM_STIM_U32(0) & 1) == 0);
+//  ITM_STIM_U32(0) = c;
 }
 
-/*********************************************************************
-*
-* SWO_PrintString()
-*
-* @brief Print a string via SWO.
-* @param *s The string to be printed.
-*
-*/
+/**
+ *
+ * SWO_PrintString()
+ *
+ * @brief Print a string via SWO.
+ * @param *s The string to be printed.
+ *
+ */
 void SWO_PrintString(const char *s) {
-  //
-  // Print out character per character
-  //
+
+  // Print out characters until \0
   while (*s) {
     SWO_PrintChar(*s++);
   }