1 /* vi: set sw=4 ts=4: */
3 * June 30, 2001 Manuel Novoa III
5 * All-integer version (hey, not everyone has floating point) of
6 * make_human_readable_str, modified from similar code I had written
7 * for busybox several months ago.
10 * 1) I'm using an unsigned long long to hold the product size * block_size,
11 * as df (which calls this routine) could request a representation of a
12 * partition size in bytes > max of unsigned long. If long longs aren't
13 * available, it would be possible to do what's needed using polynomial
14 * representations (say, powers of 1024) and manipulating coefficients.
15 * The base ten "bytes" output could be handled similarly.
17 * 2) This routine always outputs a decimal point and a tenths digit when
18 * display_unit != 0. Hence, it isn't uncommon for the returned string
19 * to have a length of 5 or 6.
21 * It might be nice to add a flag to indicate no decimal digits in
22 * that case. This could be either an additional parameter, or a
23 * special value of display_unit. Such a flag would also be nice for du.
25 * Some code to omit the decimal point and tenths digit is sketched out
26 * and "#if 0"'d below.
28 * Licensed under GPLv2, see file LICENSE in this tarball for details.
33 const char* FAST_FUNC make_human_readable_str(unsigned long long size,
34 unsigned long block_size, unsigned long display_unit)
36 /* The code will adjust for additional (appended) units */
37 static const char unit_chars[] ALIGN1 = {
38 '\0', 'K', 'M', 'G', 'T', 'P', 'E'
40 static const char fmt[] ALIGN1 = "%llu";
41 static const char fmt_tenths[] ALIGN1 = "%llu.%d%c";
43 static char str[21] ALIGN1; /* Sufficient for 64 bit unsigned integers */
45 unsigned long long val;
54 /* If block_size is 0 then do not print tenths */
56 if (block_size == 0) {
62 val = size * block_size;
67 val += display_unit/2; /* Deal with rounding */
68 val /= display_unit; /* Don't combine with the line above!!! */
69 /* will just print it as ulonglong (below) */
72 && (u < unit_chars + sizeof(unit_chars) - 1)
76 frac = (((int)(val % 1024)) * 10 + 1024/2) / 1024;
79 if (frac >= 10) { /* We need to round up here. */
84 /* Sample code to omit decimal point and tenths digit. */
89 f = "%llu%*c" /* fmt_no_tenths */;
95 /* If f==fmt then 'frac' and 'u' are ignored. */
96 snprintf(str, sizeof(str), f, val, frac, *u);