From: Tim Bird <tim.bird@am.sony.com>
To: Greg KH <gregkh@linuxfoundation.org>,
linux-embedded <linux-embedded@vger.kernel.org>,
linux kernel <linux-kernel@vger.kernel.org>,
Brian Swetland <swetland@google.com>,
Dima Zavin <dima@android.com>, Andrew Morton <akpm@osdl.org>
Subject: [PATCH 4/5] logger: clarify code in clock_interval
Date: Tue, 7 Feb 2012 18:32:02 -0800 [thread overview]
Message-ID: <4F31DEA2.7000702@am.sony.com> (raw)
In-Reply-To: <4F31DC31.6040303@am.sony.com>
Add commentary, rename the function and make the code easier to read.
Signed-off-by: Tim Bird <tim.bird@am.sony.com>
---
drivers/staging/android/logger.c | 28 ++++++++++++++++++++--------
1 files changed, 20 insertions(+), 8 deletions(-)
diff --git a/drivers/staging/android/logger.c b/drivers/staging/android/logger.c
index 54b7cdf..8d9d4f1 100644
--- a/drivers/staging/android/logger.c
+++ b/drivers/staging/android/logger.c
@@ -242,16 +242,28 @@ static size_t get_next_entry(struct logger_log *log, size_t off, size_t len)
}
/*
- * clock_interval - is a < c < b in mod-space? Put another way, does the line
- * from a to b cross c?
+ * is_between - is a < c < b, accounting for wrapping of a, b, and c
+ * positions in the buffer
+ *
+ * That is, if a<b, check for c between a and b
+ * and if a>b, check for c outside (not between) a and b
+ *
+ * |------- a xxxxxxxx b --------|
+ * c^
+ *
+ * |xxxxx b --------- a xxxxxxxxx|
+ * c^
+ * or c^
*/
-static inline int clock_interval(size_t a, size_t b, size_t c)
+static inline int is_between(size_t a, size_t b, size_t c)
{
- if (b < a) {
- if (a < c || b >= c)
+ if (a < b) {
+ /* is c between a and b? */
+ if (a < c && c <= b)
return 1;
} else {
- if (a < c && b >= c)
+ /* is c outside of b through a? */
+ if (c <= b || a < c)
return 1;
}
@@ -272,11 +284,11 @@ static void fix_up_readers(struct logger_log *log, size_t len)
size_t new = logger_offset(log, old + len);
struct logger_reader *reader;
- if (clock_interval(old, new, log->head))
+ if (is_between(old, new, log->head))
log->head = get_next_entry(log, log->head, len);
list_for_each_entry(reader, &log->readers, list)
- if (clock_interval(old, new, reader->r_off))
+ if (is_between(old, new, reader->r_off))
reader->r_off = get_next_entry(log, reader->r_off, len);
}
--
1.7.2.3
next prev parent reply other threads:[~2012-02-08 2:32 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-08 2:21 [PATCH 1/5] logger: Change logger_offset() from macro to function Tim Bird
2012-02-08 2:28 ` [PATCH 2/5] logger: simplify and optimize get_entry_len Tim Bird
2012-02-08 18:37 ` [PATCH 2/5 v2] " Tim Bird
2012-02-09 5:15 ` Dima Zavin
2012-02-09 5:58 ` Tim Bird
2012-02-08 2:30 ` [PATCH 3/5] logger: reorder prepare_to_wait and mutex_lock Tim Bird
2012-02-09 5:56 ` Dima Zavin
2012-02-08 2:32 ` Tim Bird [this message]
2012-02-09 6:09 ` [PATCH 4/5] logger: clarify code in clock_interval Dima Zavin
2012-02-08 2:34 ` [PATCH 5/5] logger: clarify non-update of w_off in do_write_log_from_user Tim Bird
2012-02-09 6:10 ` Dima Zavin
2012-02-08 3:22 ` [PATCH 1/5] logger: Change logger_offset() from macro to function Frank Rowand
2012-02-09 4:54 ` Dima Zavin
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