Date: Fri, 25 Mar 2011 02:46:58 +0000 From: Alexander Best <arundel@freebsd.org> To: freebsd-hackers@freebsd.org Subject: Re: Switching to [KMGTPE]i prefixes? Message-ID: <20110325024658.GA19544@freebsd.org> In-Reply-To: <20110325015508.GA14565@freebsd.org> References: <20110325002115.GA323@freebsd.org> <20110325015508.GA14565@freebsd.org>
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here is a revised patch. it also includes the necessary changes to the
humanize_number(3) man page.
cheers.
alex
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diff --git a/lib/libutil/humanize_number.3 b/lib/libutil/humanize_number.3
index 82925ba..841da3f 100644
--- a/lib/libutil/humanize_number.3
+++ b/lib/libutil/humanize_number.3
@@ -68,17 +68,22 @@ then divide
by 1024 until it will.
In this case, prefix
.Fa suffix
-with the appropriate SI designator.
+with the appropriate SI (or IEC) designator.
The
.Fn humanize_number
function
-follows the traditional computer science conventions rather than the proposed
-SI power of two convention.
+follows the traditional computer science conventions by default rather than the proposed
+IEC power of two convention or the power of ten notion.
+This behaviour however can be altered by the
+.Dv HN_DIVISOR_1000
+and
+.Dv HN_IEC_PREFIXES
+flags.
.Pp
-The prefixes are:
+The default prefixes are:
.Bl -column "Prefix" "Description" "1000000000000000000" -offset indent
.It Sy "Prefix" Ta Sy "Description" Ta Sy "Multiplier" Ta Sy "Multiplier 1000x"
-.It Li k Ta No kilo Ta 1024 Ta 1000
+.It Li * Ta No kilo Ta 1024 Ta 1000
.It Li M Ta No mega Ta 1048576 Ta 1000000
.It Li G Ta No giga Ta 1073741824 Ta 1000000000
.It Li T Ta No tera Ta 1099511627776 Ta 1000000000000
@@ -86,6 +91,19 @@ The prefixes are:
.It Li E Ta No exa Ta 1152921504606846976 Ta 1000000000000000000
.El
.Pp
+* An uppercase K indicates a power of two, a lowercase k a power of ten.
+.Pp
+The IEC power of two (IEC 80000-13) prefixes are:
+.Bl -column "Prefix" "Description" "1000000000000000000" -offset indent
+.It Sy "Prefix" Ta Sy "Description" Ta Sy "Multiplier"
+.It Li Ki Ta No kibi Ta 1024
+.It Li Mi Ta No mebi Ta 1048576
+.It Li Gi Ta No gibi Ta 1073741824
+.It Li Ti Ta No tebi Ta 1099511627776
+.It Li Pi Ta No pebi Ta 1125899906842624
+.It Li Ei Ta No exbi Ta 1152921504606846976
+.El
+.Pp
The
.Fa len
argument must be at least 4 plus the length of
@@ -127,6 +145,11 @@ Use
Divide
.Fa number
with 1000 instead of 1024.
+.It Dv HN_IEC_PREFIXES
+Use the IEC notion of prefixes (Ki, Mi, Gi...).
+This flag has no effect when
+.Dv HN_DIVISOR_1000
+is also specified.
.El
.Sh RETURN VALUES
The
@@ -148,3 +171,7 @@ function first appeared in
.Nx 2.0
and then in
.Fx 5.3 .
+The
+.Dv HN_IEC_PREFIXES
+flag was introduced in
+.Fx 9.0 .
diff --git a/lib/libutil/humanize_number.c b/lib/libutil/humanize_number.c
index 75bcb46..efa06cb 100644
--- a/lib/libutil/humanize_number.c
+++ b/lib/libutil/humanize_number.c
@@ -47,7 +47,7 @@ humanize_number(char *buf, size_t len, int64_t quotient,
const char *suffix, int scale, int flags)
{
const char *prefixes, *sep;
- int i, r, remainder, maxscale, s1, s2, sign;
+ int i, r, remainder, maxscale, s1, s2, shift, sign;
int64_t divisor, max;
size_t baselen;
@@ -57,26 +57,41 @@ humanize_number(char *buf, size_t len, int64_t quotient,
remainder = 0;
+ /*
+ * With HN_DIVISOR_1000 defined, SI prefixes for decimal multiplies
+ * are used. Without this flag, the raditional power of two prefixes
+ * are used. If however HN_IEC_PREFIXES is defined, the power of
+ * two prefixes recommended by the International Electrotechnical
+ * Commission (IEC) in IEC 80000-3 (superseeding IEC 60027-2)
+ * (i.e. Ki, Mi, Gi...) are used.
+ *
+ * Please note that HN_DIVISOR_1000 takes priority over HN_IEC_PREFIXES.
+ * The default behavior is to use the traditional power of two prefixes.
+ */
if (flags & HN_DIVISOR_1000) {
- /* SI for decimal multiplies */
divisor = 1000;
+ shift = 1;
if (flags & HN_B)
prefixes = "B\0k\0M\0G\0T\0P\0E";
else
prefixes = "\0\0k\0M\0G\0T\0P\0E";
+ } else if (flags & HN_IEC_PREFIXES) {
+ divisor = 1024;
+ shift = 2;
+ if (flags & HN_B)
+ prefixes = "B\0\0\0Ki\0\0Mi\0\0Gi\0\0Ti\0\0Pi\0\0Ei";
+ else
+ prefixes = "\0\0\0\0Ki\0\0Mi\0\0Gi\0\0Ti\0\0Pi\0\0Ei";
} else {
- /*
- * binary multiplies
- * XXX IEC 60027-2 recommends Ki, Mi, Gi...
- */
divisor = 1024;
+ shift = 1;
if (flags & HN_B)
prefixes = "B\0K\0M\0G\0T\0P\0E";
else
prefixes = "\0\0K\0M\0G\0T\0P\0E";
}
-#define SCALE2PREFIX(scale) (&prefixes[(scale) << 1])
+#define SCALE2PREFIX(scale) (&prefixes[(scale) << shift])
maxscale = 7;
if (scale >= maxscale &&
@@ -102,6 +117,10 @@ humanize_number(char *buf, size_t len, int64_t quotient,
sep = " ";
baselen++;
}
+ if (flags & HN_IEC_PREFIXES) {
+ baselen ++;
+ len ++;
+ }
baselen += strlen(suffix);
/* Check if enough room for `x y' + suffix + `\0' */
diff --git a/lib/libutil/libutil.h b/lib/libutil/libutil.h
index 66104e9..295a8d3 100644
--- a/lib/libutil/libutil.h
+++ b/lib/libutil/libutil.h
@@ -220,6 +220,7 @@ __END_DECLS
#define HN_NOSPACE 0x02
#define HN_B 0x04
#define HN_DIVISOR_1000 0x08
+#define HN_IEC_PREFIXES 0x0f
#define HN_GETSCALE 0x10
#define HN_AUTOSCALE 0x20
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