From 62a6638eb544f2c3d9022bcb34cae181aa8f7aae Mon Sep 17 00:00:00 2001
From: gdisirio <gdisirio@35acf78f-673a-0410-8e92-d51de3d6d3f4>
Date: Sun, 3 May 2009 09:51:01 +0000
Subject: Added I/O queue checks to the channels, added notes in the readme,
 improved the FullDuplexDriver.

git-svn-id: svn://svn.code.sf.net/p/chibios/svn/trunk@940 35acf78f-673a-0410-8e92-d51de3d6d3f4
---
 src/chserial.c         | 16 +++++++++++++++-
 src/include/channels.h | 34 ++++++++++++++++++++++++++++++++++
 src/include/serial.h   | 18 ++++++++++++++++++
 3 files changed, 67 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/chserial.c b/src/chserial.c
index 4dac892f8..65179689d 100644
--- a/src/chserial.c
+++ b/src/chserial.c
@@ -28,6 +28,20 @@
 
 #if CH_USE_SERIAL_FULLDUPLEX
 
+/*
+ * Interface implementation, the following functions just invoke the equivalent
+ * queue-level function or macro.
+ */
+static bool_t putwouldblock(void *instance) {
+
+  return chOQIsFull(&((FullDuplexDriver *)instance)->d2.oqueue);
+}
+
+static bool_t getwouldblock(void *instance) {
+
+  return chIQIsEmpty(&((FullDuplexDriver *)instance)->d2.iqueue);
+}
+
 static msg_t put(void *instance, uint8_t b, systime_t timeout) {
 
   return chOQPutTimeout(&((FullDuplexDriver *)instance)->d2.oqueue, b, timeout);
@@ -49,7 +63,7 @@ static size_t read(void *instance, uint8_t *buffer, size_t n) {
 }
 
 static const struct FullDuplexDriverVMT vmt = {
-  {put, get},
+  {putwouldblock, getwouldblock, put, get},
   {write, read},
   {}
 };
diff --git a/src/include/channels.h b/src/include/channels.h
index d3d1f5d47..2ff20b1ad 100644
--- a/src/include/channels.h
+++ b/src/include/channels.h
@@ -31,6 +31,16 @@
  * @brief @p BaseChannel specific methods.
  */
 struct _base_channel_methods {
+  /**
+   * @brief Channel output check.
+   * @see chIOPutWouldBlock()
+   */
+  bool_t (*putwouldblock)(void *instance);
+  /**
+   * @brief Channel input check.
+   * @see chIOGetWouldBlock()
+   */
+  bool_t (*getwouldblock)(void *instance);
   /**
    * @brief Channel put method with timeout specification.
    * @see chIOPut()
@@ -76,6 +86,30 @@ typedef struct {
   struct _base_channel_data d0;
 } BaseChannel;
 
+/**
+ * @brief Channel output check.
+ * @details This function verifies if a subsequent @p chIOPut() would block.
+ *
+ * @param[in] ip pointer to a @p BaseChannel or derived class
+ * @return The output queue status:
+ * @retval FALSE if the output queue has space and would not block a write
+ *         operation.
+ * @retval TRUE if the output queue is full and would block a write operation.
+ */
+#define chIOPutWouldBlock(ip) ((ip)->vmt->m0.putwouldblock(ip))
+
+/**
+ * @brief Channel input check.
+ * @details This function verifies if a subsequent @p chIOGett() would block.
+ *
+ * @param[in] ip pointer to a @p BaseChannel or derived class
+ * @return The input queue status:
+ * @retval FALSE if the input queue contains data and would not block a read
+ *         operation.
+ * @retval TRUE if the input queue is empty and would block a read operation.
+ */
+#define chIOGetWouldBlock(ip) ((ip)->vmt->m0.getwouldblock(ip))
+
 /**
  * @brief Channel blocking byte write.
  * @details This function writes a byte value to a channel. If the channel
diff --git a/src/include/serial.h b/src/include/serial.h
index 9bb6c4f92..08ddf61fe 100644
--- a/src/include/serial.h
+++ b/src/include/serial.h
@@ -136,6 +136,24 @@ extern "C" {
 }
 #endif
 
+/**
+ * @brief Direct output check on a @p FullDuplexDriver.
+ * @details This function bypasses the indirect access to the channel and
+ *          checks directly the output queue. This is faster but cannot
+ *          be used to check different channels implementations.
+ * @see chIOPutWouldBlock()
+ */
+#define chFDDPutWouldBlock(sd) chOQIsFull(&(sd)->d2.oqueue)
+
+/**
+ * @brief Direct input check on a @p FullDuplexDriver.
+ * @details This function bypasses the indirect access to the channel and
+ *          checks directly the input queue. This is faster but cannot
+ *          be used to check different channels implementations.
+ * @see chIOGetWouldBlock()
+ */
+#define chFDDGetWouldBlock(sd) chIQIsEmpty(&(sd)->d2.iqueue)
+
 /**
  * @brief Direct blocking write to a @p FullDuplexDriver.
  * @details This function bypasses the indirect access to the channel and
-- 
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