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Subject[PATCH 2/5] logger: simplify and optimize get_entry_len
Make this code slightly easier to read, and eliminate calls
to sub-routines. Some of these were previously optimized away
by the compiler, but one memcpy was not.

Signed-off-by: Tim Bird <tim.bird@am.sony.com>
---
drivers/staging/android/logger.c | 18 +++++++++++-------
1 files changed, 11 insertions(+), 7 deletions(-)
diff --git a/drivers/staging/android/logger.c b/drivers/staging/android/logger.c
index 92456d7..92cfd94 100644
--- a/drivers/staging/android/logger.c
+++ b/drivers/staging/android/logger.c
@@ -93,19 +93,23 @@ static inline struct logger_log *file_get_log(struct file *file)
* get_entry_len - Grabs the length of the payload of the next entry starting
* from 'off'.
*
+ * An entry length is 2 bytes (16 bits) in host endian order.
+ * In the log, the length does not include the size of the log entry structure.
+ * This function returns the size including the log entry structure.
+ *
* Caller needs to hold log->mutex.
*/
static __u32 get_entry_len(struct logger_log *log, size_t off)
{
__u16 val;

- switch (log->size - off) {
- case 1:
- memcpy(&val, log->buffer + off, 1);
- memcpy(((char *) &val) + 1, log->buffer, 1);
- break;
- default:
- memcpy(&val, log->buffer + off, 2);
+ if (unlikely(log->size - off == 1)) {
+ /* at end of buffer, handle wrap */
+ ((unsigned char *)&val)[0] = log->buffer[off];
+ ((unsigned char *)&val)[1] = log->buffer[0];
+ } else {
+ ((unsigned char *)&val)[0] = log->buffer[off];
+ ((unsigned char *)&val)[1] = log->buffer[off+1];
}

return sizeof(struct logger_entry) + val;
--
1.7.2.3


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