1 files changed, 59 insertions, 0 deletions
diff --git a/Libraries/TouchSense/stmCriticalSection.c b/Libraries/TouchSense/stmCriticalSection.c
new file mode 100644
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+++ b/Libraries/TouchSense/stmCriticalSection.c
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+/******************** (C) COPYRIGHT 2014 STMicroelectronics ********************
+* File Name          : stmCriticalSection.c
+* Author             : MCD Tools Development
+* Version            : V1.0
+* Date               : 21/02/2013
+* Description        : This file provides a mechanism for STMStudio host/target
+*                      synchronization. Based on a critical section, using few
+*                      target resources (in term of code and RAM), but
+*                      potentially impacting the application runtime (possible
+*                      waiting loop when enterring the critical section).
+********************************************************************************
+* THE PRESENT SOFTWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS
+* WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE TIME.
+* AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY DIRECT,
+* INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING FROM THE
+* CONTENT OF SUCH SOFTWARE AND/OR THE USE MADE BY CUSTOMERS OF THE CODING
+* INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.
+*******************************************************************************/
+
+/* Implementation of Peterson's algorithm for mutual exclusive access to
+   data, between the STMStudio host and the target processor.
+	 The use of the critical section ensures the coherence of a set of data: it is
+	 not possible for the STMStudio host to read data while the target is in the
+	 critical section.
+	 The target should enter the critical section (waiting loop possible, if the
+	 STMStudio host is being reading) before modifying data that are identified as
+	 critical ones. Then leave the critical section in order to allow the
+	 STMStudio host to read them.
+	 The host also enters the critical section before each reading, and leaves it
+	 afterwards.
+	 Note that it is not mandatory for the target to protect all spied variables
+	 into the critical section; and that the synchronization might generate
+	 relatively long waiting loops on the target side. As a result the critical
+	 section should be used only for word-variables or group of variables for
+	 which the coherence is important.
+*/
+
+#include "stmCriticalSection.h"
+
+#define TARGET_LOCK_ID 0 // Do not modify - shared with STMStudio host software
+#define HOST_LOCK_ID   1 // Do not modify - shared with STMStudio host software
+
+typedef struct petersons_t {
+    volatile unsigned char flag[2]; // Do not modify - shared with STMStudio host software
+    volatile unsigned char turn;    // Do not modify - shared with STMStudio host software
+} petersons_t;
+
+// stm_studio_lock symbol used by the STMStudio host software for synchronization
+petersons_t stm_studio_lock = { { 0, 0 }, TARGET_LOCK_ID }; // Do not modify - shared with STMStudio host software
+
+void enterLock (void) {
+    stm_studio_lock.flag[TARGET_LOCK_ID] = 1;
+    stm_studio_lock.turn = HOST_LOCK_ID;
+    while (stm_studio_lock.flag[HOST_LOCK_ID] && (stm_studio_lock.turn == HOST_LOCK_ID)) {}
+}
+
+void exitLock (void) {
+    stm_studio_lock.flag[TARGET_LOCK_ID] = 0;
+}