Changeset c657bd7 in mainline for uspace/lib/c/generic/io/chardev.c

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/lib/c/generic/io/chardev.c (modified) (3 diffs)

uspace/lib/c/generic/io/chardev.c

@@ -77 +77 @@
 }
 
-int chardev_read(chardev_t *chardev, void *data, size_t size, size_t *nread)
+/** Read from character device.
+ *
+ * Read as much data as is available from character device up to @a size
+ * bytes into @a buf. On success EOK is returned and at least one byte
+ * is read (if no byte is available the function blocks). The number
+ * of bytes read is stored in @a *nread.
+ *
+ * On error a non-zero error code is returned and @a *nread is filled with
+ * the number of bytes that were successfully transferred.
+ *
+ * @param chardev Character device
+ * @param buf Destination buffer
+ * @param size Maximum number of bytes to read
+ * @param nread Place to store actual number of bytes read
+ *
+ * @return EOK on success or non-zero error code
+ */
+int chardev_read(chardev_t *chardev, void *buf, size_t size, size_t *nread)
 {
         if (size > 4 * sizeof(sysarg_t))
@@ -88 +105 @@
         async_exchange_end(exch);
         if (ret > 0 && (size_t)ret <= size)
-                memcpy(data, message, size);
+                memcpy(buf, message, size);
 
         if (ret < 0) {
@@ -99 +116 @@
 }
 
+/** Write to character device.
+ *
+ * Write @a size bytes from @a data to character device. On success EOK
+ * is returned, all bytes were written and @a *nwritten is set to @a size.
+ *
+ * On error a non-zero error code is returned and @a *nwritten is filled with
+ * the number of bytes that were successfully transferred.
+ *
+ * @param chardev Character device
+ * @param buf Destination buffer
+ * @param size Maximum number of bytes to read
+ * @param nwritten Place to store actual number of bytes written
+ *
+ * @return EOK on success or non-zero error code
+ */
 int chardev_write(chardev_t *chardev, const void *data, size_t size,
     size_t *nwritten)