Changeset c657bd7 in mainline for uspace/drv/char/i8042/buffer.h

Timestamp:

2017-11-20T10:06:59Z (6 years ago)

Author:

Jiri Svoboda <jiri@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

19ea61d

Parents:

5d50c419

git-author:

Jiri Svoboda <jiri@…> (2017-11-19 22:05:26)

git-committer:

Jiri Svoboda <jiri@…> (2017-11-20 10:06:59)

Message:

Less is sometimes more. Need chardev_read to be able to return less bytes than requested if less is available. Otherwise cannot read variable-sized packets except yte-by-byte.

File:

• uspace/drv/char/i8042/buffer.h (modified) (2 diffs)

uspace/drv/char/i8042/buffer.h

@@ -113 +113 @@
  *
  * @param buffer Cyclic buffer to read from.
+ * @param rb Place to store byte read
+ * @param wait @c True to wait until byte is available
  *
- * @return Byte read.
+ * @return EOK on success, EAGAIN if @c wait is false and no data is available
  *
  */
-static inline uint8_t buffer_read(buffer_t *buffer)
+static inline int buffer_read(buffer_t *buffer, uint8_t *rb, bool wait)
 {
         fibril_mutex_lock(&buffer->guard);
         
         /* Buffer is empty. */
-        while (buffer->write_head == buffer->read_head)
+        while (wait && buffer->write_head == buffer->read_head)
                 fibril_condvar_wait(&buffer->change, &buffer->guard);
+        
+        if (buffer->write_head == buffer->read_head) {
+                fibril_mutex_unlock(&buffer->guard);
+                return EAGAIN;
+        }
         
         /* Next position. */
@@ -144 +151 @@
         
         fibril_mutex_unlock(&buffer->guard);
-        return data;
+        *rb = data;
+        return EOK;
 }