* [PATCH V2] nandwrite: Factor out buffer checking code
@ 2016-12-09 1:47 Marek Vasut
2016-12-09 7:49 ` Boris Brezillon
0 siblings, 1 reply; 3+ messages in thread
From: Marek Vasut @ 2016-12-09 1:47 UTC (permalink / raw)
To: linux-mtd; +Cc: Marek Vasut, Boris Brezillon, David Oberhollenzer, Kees Trommel
Pull the buffer content checking code into separate function and
simplify the code invoking it slightly.
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Cc: Kees Trommel <ctrommel@aimvalley.nl>
---
include/common.h | 25 +++++++++++++++++++++++++
nand-utils/nandwrite.c | 17 +++--------------
2 files changed, 28 insertions(+), 14 deletions(-)
---
V2: Move the buffer_check_pattern() to include/common.h
diff --git a/include/common.h b/include/common.h
index 32b5d23..2812f49 100644
--- a/include/common.h
+++ b/include/common.h
@@ -181,6 +181,31 @@ static inline int is_power_of_2(unsigned long long n)
return (n != 0 && ((n & (n - 1)) == 0));
}
+/* Check whether buffer is filled with character 'pattern' */
+static inline int buffer_check_pattern(unsigned char *buffer, size_t size,
+ unsigned char pattern)
+{
+ /* Invalid input */
+ if (!buffer || (size == 0))
+ return 0;
+
+ /* No match on first byte */
+ if (*buffer != pattern)
+ return 0;
+
+ /* First byte matched and buffer is 1 byte long, OK. */
+ if (size == 1)
+ return 1;
+
+ /*
+ * Check buffer longer than 1 byte. We already know that buffer[0]
+ * matches the pattern, so the test below only checks whether the
+ * buffer[0...size-2] == buffer[1...size-1] , which is a test for
+ * whether the buffer is filled with constant value.
+ */
+ return !memcmp(buffer, buffer + 1, size - 1);
+}
+
/**
* simple_strtoX - convert a hex/dec/oct string into a number
* @snum: buffer to convert
diff --git a/nand-utils/nandwrite.c b/nand-utils/nandwrite.c
index b376869..9602a6e 100644
--- a/nand-utils/nandwrite.c
+++ b/nand-utils/nandwrite.c
@@ -523,18 +523,8 @@ int main(int argc, char * const argv[])
}
}
- allffs = 0;
- if (skipallffs)
- {
- for (ii = 0; ii < mtd.min_io_size; ii += sizeof(uint32_t))
- {
- if (*(uint32_t*)(writebuf + ii) != 0xffffffff)
- break;
- }
- if (ii == mtd.min_io_size)
- allffs = 1;
- }
- if (!allffs) {
+ ret = 0;
+ if (!skipallffs || !buffer_check_pattern(writebuf, mtd.min_io_size, 0xff)) {
/* Write out data */
ret = mtd_write(mtd_desc, &mtd, fd, mtdoffset / mtd.eb_size,
mtdoffset % mtd.eb_size,
@@ -543,9 +533,8 @@ int main(int argc, char * const argv[])
writeoob ? oobbuf : NULL,
writeoob ? mtd.oob_size : 0,
write_mode);
- } else {
- ret = 0;
}
+
if (ret) {
long long i;
if (errno != EIO) {
--
2.10.2
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH V2] nandwrite: Factor out buffer checking code
2016-12-09 1:47 [PATCH V2] nandwrite: Factor out buffer checking code Marek Vasut
@ 2016-12-09 7:49 ` Boris Brezillon
2016-12-09 8:25 ` David Oberhollenzer
0 siblings, 1 reply; 3+ messages in thread
From: Boris Brezillon @ 2016-12-09 7:49 UTC (permalink / raw)
To: Marek Vasut; +Cc: linux-mtd, David Oberhollenzer, Kees Trommel
On Fri, 9 Dec 2016 02:47:41 +0100
Marek Vasut <marex@denx.de> wrote:
> Pull the buffer content checking code into separate function and
> simplify the code invoking it slightly.
>
> Signed-off-by: Marek Vasut <marex@denx.de>
> Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> Cc: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
> Cc: Kees Trommel <ctrommel@aimvalley.nl>
> ---
> include/common.h | 25 +++++++++++++++++++++++++
> nand-utils/nandwrite.c | 17 +++--------------
> 2 files changed, 28 insertions(+), 14 deletions(-)
> ---
> V2: Move the buffer_check_pattern() to include/common.h
>
> diff --git a/include/common.h b/include/common.h
> index 32b5d23..2812f49 100644
> --- a/include/common.h
> +++ b/include/common.h
> @@ -181,6 +181,31 @@ static inline int is_power_of_2(unsigned long long n)
> return (n != 0 && ((n & (n - 1)) == 0));
> }
>
> +/* Check whether buffer is filled with character 'pattern' */
> +static inline int buffer_check_pattern(unsigned char *buffer, size_t size,
> + unsigned char pattern)
> +{
> + /* Invalid input */
> + if (!buffer || (size == 0))
> + return 0;
> +
> + /* No match on first byte */
> + if (*buffer != pattern)
> + return 0;
> +
> + /* First byte matched and buffer is 1 byte long, OK. */
> + if (size == 1)
> + return 1;
> +
> + /*
> + * Check buffer longer than 1 byte. We already know that buffer[0]
> + * matches the pattern, so the test below only checks whether the
> + * buffer[0...size-2] == buffer[1...size-1] , which is a test for
> + * whether the buffer is filled with constant value.
> + */
> + return !memcmp(buffer, buffer + 1, size - 1);
> +}
> +
> /**
> * simple_strtoX - convert a hex/dec/oct string into a number
> * @snum: buffer to convert
> diff --git a/nand-utils/nandwrite.c b/nand-utils/nandwrite.c
> index b376869..9602a6e 100644
> --- a/nand-utils/nandwrite.c
> +++ b/nand-utils/nandwrite.c
> @@ -523,18 +523,8 @@ int main(int argc, char * const argv[])
> }
> }
>
> - allffs = 0;
> - if (skipallffs)
> - {
> - for (ii = 0; ii < mtd.min_io_size; ii += sizeof(uint32_t))
> - {
> - if (*(uint32_t*)(writebuf + ii) != 0xffffffff)
> - break;
> - }
> - if (ii == mtd.min_io_size)
> - allffs = 1;
> - }
> - if (!allffs) {
> + ret = 0;
> + if (!skipallffs || !buffer_check_pattern(writebuf, mtd.min_io_size, 0xff)) {
> /* Write out data */
> ret = mtd_write(mtd_desc, &mtd, fd, mtdoffset / mtd.eb_size,
> mtdoffset % mtd.eb_size,
> @@ -543,9 +533,8 @@ int main(int argc, char * const argv[])
> writeoob ? oobbuf : NULL,
> writeoob ? mtd.oob_size : 0,
> write_mode);
> - } else {
> - ret = 0;
> }
> +
> if (ret) {
> long long i;
> if (errno != EIO) {
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH V2] nandwrite: Factor out buffer checking code
2016-12-09 7:49 ` Boris Brezillon
@ 2016-12-09 8:25 ` David Oberhollenzer
0 siblings, 0 replies; 3+ messages in thread
From: David Oberhollenzer @ 2016-12-09 8:25 UTC (permalink / raw)
To: Boris Brezillon, Marek Vasut; +Cc: linux-mtd, Kees Trommel
On 12/09/2016 08:49 AM, Boris Brezillon wrote:
> On Fri, 9 Dec 2016 02:47:41 +0100
> Marek Vasut <marex@denx.de> wrote:
>
>> Pull the buffer content checking code into separate function and
>> simplify the code invoking it slightly.
>>
>> Signed-off-by: Marek Vasut <marex@denx.de>
>> Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
>
> Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Looks good to me too.
On 12/09/2016 02:49 AM, Marek Vasut wrote:
> OK, done and V2 out. But it'd be great if someone could actually test it
> :-) Kees ?
>
>
>From looking at the code, it looks perfectly reasonable and I don't see
why it shouldn't work.
Anyway, I took the code snippet and ran an exhaustive test on all 32 bit
integers. It appears to work as intended.
Applied to mtd-utils.git.
Thanks,
David
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-12-09 7:49 ` Boris Brezillon
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