From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim Bird Subject: [PATCH 2/5] logger: simplify and optimize get_entry_len Date: Tue, 7 Feb 2012 18:28:23 -0800 Message-ID: <4F31DDC7.1050107@am.sony.com> References: <4F31DC31.6040303@am.sony.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4F31DC31.6040303@am.sony.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Greg KH , linux-embedded , linux kernel , Brian Swetland , Dima Zavin , Andrew Morton 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 --- 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