Added descriptions and code simplified

demos/STM32/RT-STM32F429-DISCOVERY-DMA2D/main.c

@@ -474,8 +474,6 @@ static void dma2d_test(void) {
 /* Command line related.                                                     */
 /*===========================================================================*/
 
-#define     RTT2MS(ticks)   ((ticks) / (STM32_HCLK / 1000UL))
-
 #if HAL_USE_SERIAL_USB
 /* Virtual serial port over USB.*/
 SerialUSBDriver SDU1;

demos/STM32/RT-STM32F429-DISCOVERY-TRIBUF/main.c

@@ -66,33 +66,37 @@ static char buffer_a, buffer_b, buffer_c;
 
 static const char text[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ\r\n";
 
-/*
- * Reads from the front buffer.
+/**
+ * @brief   Reads from the front buffer.
+ *
+ * @return  Buffered character from @p text or special symbol.
+ * @retval '.'  No new front buffer within timeout.
  */
 static char read_front(void) {
 
   const char *front;
   msg_t error;
+  char c;
 
   /* Wait until a new front buffer gets available with prepared data */
-  chSysLock();
-  error = tribufWaitReadyTimeoutS(&tribuf_handler, reader_timeout);
-  if (error == MSG_TIMEOUT) {
-    chSysUnlock();
-    return (reader_timeout == TIME_IMMEDIATE) ? '.' : '@';
+  error = tribufWaitReadyTimeout(&tribuf_handler, reader_timeout);
+  if (error == MSG_OK) {
+    /* Retrieve the new front buffer */
+    tribufSwapFront(&tribuf_handler);
+    front = (const char *)tribufGetFront(&tribuf_handler);
+
+    /* Read data from the new front buffer */
+    c = front[0];
+  } else {
+    c = '.';  /* Timeout placeholder */
   }
-  chSysUnlock();
-
-  /* Retrieve the new front buffer */
-  tribufSwapFront(&tribuf_handler);
-  front = (const char *)tribufGetFront(&tribuf_handler);
-
-  /* Read data from the new front buffer */
-  return front[0];
+  return c;
 }
 
 /*
- * Overwrites the back buffer with the provided character.
+ * @brief   Overwrites the back buffer with the provided character.
+ *
+ * @param[in] c   Character to store into the current back buffer.
  */
 static void write_back(char c) {
 
@@ -123,9 +127,11 @@ static THD_FUNCTION(reader_thread, arg) {
   old_priority = chThdGetPriorityX();
 
   for (;;) {
+    /* Read from the fron buffer and print the retrieved character */
     c = read_front();
     chprintf(chout, "%c", c);
 
+    /* Change priority, suspend or delay */
     osalSysLock();
     palTogglePad(GPIOG, GPIOG_LED3_GREEN);
     if (old_priority != reader_priority) {
@@ -160,9 +166,11 @@ static THD_FUNCTION(writer_thread, arg) {
 
   for (;;) {
     for (i = 0; i < sizeof(text); ++i) {
+      /* Write the next character on the current back buffer */
       c = text[i];
       write_back(c);
 
+      /* Change priority, suspend or delay */
       osalSysLock();
       palTogglePad(GPIOG, GPIOG_LED4_RED);
       if (old_priority != writer_priority) {

demos/STM32/RT-STM32F429-DISCOVERY-TRIBUF/readme.txt

@@ -8,20 +8,23 @@ The demo runs on an ST STM32F429I-Discovery board.
 
 ** The Demo **
 
-A simple command shell is activated on virtual serial port SD1.
-TODO
+This demo shows how to use a triple buffer handler, with one writer thread and
+one reader thread.
+The writer thread puts a character into the current back buffer, thus swapping
+the back buffer with the orphan buffer for a new write. The writer then sleeps
+for a specified delay in milliseconds.
+The reader thread gets waits (if there is a timeout) until the orphan buffer
+contains available data, becoming the new front buffer. The character is read
+from the new front buffer and printed. The reader then sleeps for a specified
+delay in milliseconds.
+A simple command shell is activated on virtual serial port SD1 or SDU1.
+Via command line it is possible to start, stop, set the delay, and set the
+thread priority of the reader and writer threads.
+The reader can also be assigned a wait timeout in milliseconds, with special
+cases of "*" for infinite timeout, and "-" (or 0 ms) for none.
 
 ** Build Procedure **
 
-The demo has been tested by using the free Codesourcery GCC-based toolchain
-and YAGARTO. just modify the TRGT line in the makefile in order to use
+The demo has been tested by using the free GNU Tools ARM Embedded toolchain
+and ChibiStudio. Just modify the TRGT line in the makefile in order to use
 different GCC toolchains.
-
-** Notes **
-
-Some files used by the demo are not part of ChibiOS/RT but are copyright of
-ST Microelectronics and are licensed under a different license.
-Also note that not all the files present in the ST library are distributed
-with ChibiOS/RT, you can find the whole library on the ST web site:
-
-                             http://www.st.com

os/various/tribuf.h

@@ -38,10 +38,10 @@
  * @{
  */
 
-#if !defined(TRIBUF_USE_WAIT) || defined(__DOXYGEN__)
 /**
  * @brief   Triple buffers use blocking functions.
  */
+#if !defined(TRIBUF_USE_WAIT) || defined(__DOXYGEN__)
 #define TRIBUF_USE_WAIT       TRUE
 #endif