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Message-Id: <20110930180242.D89C1A59@kernel>
Date: Fri, 30 Sep 2011 11:02:42 -0700
From: Dave Hansen <dave@...ux.vnet.ibm.com>
To: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org, rientjes@...gle.com,
James.Bottomley@...senPartnership.com, hpa@...or.com,
Dave Hansen <dave@...ux.vnet.ibm.com>
Subject: [RFC][PATCH 2/4] break out unit selection from string_get_size()
string_get_size() can really only print things in a single
format. You're always stuck with a space, and it will
always zero-pad the decimal places:
4.00 KiB
40.0 KiB
400 KiB
Printing page sizes in decimal KiB does not make much sense
since they are always nice powers of two. But,
string_get_size() does have some nice code for selecting
the right units and doing the division.
This breaks that nice code out so that we can reuse it.
find_size_units() is a bit of a funky function since it has
so many outputs. I don't think it's _too_ crazy though.
Signed-off-by: Dave Hansen <dave@...ux.vnet.ibm.com>
---
linux-2.6.git-dave/include/linux/string_helpers.h | 3
linux-2.6.git-dave/lib/string_helpers.c | 67 +++++++++++++++-------
2 files changed, 50 insertions(+), 20 deletions(-)
diff -puN include/linux/string_helpers.h~break-up-string_get_size-1 include/linux/string_helpers.h
--- linux-2.6.git/include/linux/string_helpers.h~break-up-string_get_size-1 2011-09-30 10:47:14.794753824 -0700
+++ linux-2.6.git-dave/include/linux/string_helpers.h 2011-09-30 10:47:14.806753800 -0700
@@ -10,6 +10,9 @@ enum string_size_units {
STRING_UNITS_2, /* use binary powers of 2^10 */
};
+u64 find_size_units(u64 *size, const enum string_size_units units,
+ const char **unit_str);
+
int string_get_size(u64 size, enum string_size_units units,
char *buf, int len);
diff -puN lib/string_helpers.c~break-up-string_get_size-1 lib/string_helpers.c
--- linux-2.6.git/lib/string_helpers.c~break-up-string_get_size-1 2011-09-30 10:47:14.798753816 -0700
+++ linux-2.6.git-dave/lib/string_helpers.c 2011-09-30 10:47:14.806753800 -0700
@@ -20,6 +20,49 @@ static int calc_sf_digit_room(u64 size)
return digits;
}
+static const char *units_10[] = { "B", "kB", "MB", "GB", "TB", "PB",
+ "EB", "ZB", "YB", NULL};
+static const char *units_2[] = {"B", "KiB", "MiB", "GiB", "TiB", "PiB",
+ "EiB", "ZiB", "YiB", NULL };
+
+static const char **units_str[] = {
+ [STRING_UNITS_10] = units_10,
+ [STRING_UNITS_2] = units_2,
+};
+static const unsigned int divisor[] = {
+ [STRING_UNITS_10] = 1000,
+ [STRING_UNITS_2] = 1024,
+};
+
+/**
+ * string_get_size - helper function for printing numbers
+ * @size: number to be printed (modified)
+ * @units: units to use (powers of 1000 or 1024)
+ * @unit_str: unit is returned in this string
+ * returns: remainder from divisions
+ *
+ * The goal here is to return a number in @size which has
+ * only 3 significant figures, along with the unit pointed
+ * to by unit_str which is necessary to make that happen.
+ *
+ * We return the remainder so that the caller does not have
+ * to repeat the division operations themselves.
+ */
+u64 find_size_units(u64 *size, const enum string_size_units units,
+ const char **unit_str)
+{
+ u64 remainder = 0;
+ int i = 0;
+
+ while (*size >= divisor[units] && units_str[units][i]) {
+ remainder = do_div(*size, divisor[units]);
+ i++;
+ }
+ *unit_str = units_str[units][i];
+ return remainder;
+}
+EXPORT_SYMBOL(find_size_units);
+
/**
* string_get_size - get the size in the specified units
* @size: The size to be converted
@@ -35,30 +78,14 @@ static int calc_sf_digit_room(u64 size)
int string_get_size(u64 size, const enum string_size_units units,
char *buf, int len)
{
- const char *units_10[] = { "B", "kB", "MB", "GB", "TB", "PB",
- "EB", "ZB", "YB", NULL};
- const char *units_2[] = {"B", "KiB", "MiB", "GiB", "TiB", "PiB",
- "EiB", "ZiB", "YiB", NULL };
- const char **units_str[] = {
- [STRING_UNITS_10] = units_10,
- [STRING_UNITS_2] = units_2,
- };
- const unsigned int divisor[] = {
- [STRING_UNITS_10] = 1000,
- [STRING_UNITS_2] = 1024,
- };
- int i, j;
+ int j;
u64 remainder = 0;
char tmp[8];
+ const char *unit_str = "";
tmp[0] = '\0';
- i = 0;
if (size >= divisor[units]) {
- while (size >= divisor[units] && units_str[units][i]) {
- remainder = do_div(size, divisor[units]);
- i++;
- }
-
+ remainder = find_size_units(&size, units, &unit_str);
j = calc_sf_digit_room(size);
if (j) {
remainder *= 1000;
@@ -70,7 +97,7 @@ int string_get_size(u64 size, const enum
}
snprintf(buf, len, "%lld%s %s", (unsigned long long)size,
- tmp, units_str[units][i]);
+ tmp, unit_str);
return 0;
}
_
--
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