1/* vi: set sw=4 ts=4: */
2/*
3 * June 30, 2001                 Manuel Novoa III
4 *
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.
8 *
9 * Notes:
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.
16 *
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.
20 *
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.
24 *
25 *      Some code to omit the decimal point and tenths digit is sketched out
26 *      and "#if 0"'d below.
27 */
28
29#include "libbb.h"
30
31const char *make_human_readable_str(unsigned long long size,
32	unsigned long block_size, unsigned long display_unit)
33{
34	/* The code will adjust for additional (appended) units */
35	static const char zero_and_units[] ALIGN1 = { '0', 0, 'k', 'M', 'G', 'T' };
36	static const char fmt[] ALIGN1 = "%llu";
37	static const char fmt_tenths[] ALIGN1 = "%llu.%d%c";
38
39	static char str[21] ALIGN1;  /* Sufficient for 64 bit unsigned integers */
40
41	unsigned long long val;
42	int frac;
43	const char *u;
44	const char *f;
45
46	u = zero_and_units;
47	f = fmt;
48	frac = 0;
49
50	val = size * block_size;
51	if (val == 0) {
52		return u;
53	}
54
55	if (display_unit) {
56		val += display_unit/2;	/* Deal with rounding */
57		val /= display_unit;	/* Don't combine with the line above!!! */
58	} else {
59		++u;
60		while ((val >= 1024)
61		 && (u < zero_and_units + sizeof(zero_and_units) - 1)
62		) {
63			f = fmt_tenths;
64			++u;
65			frac = (((int)(val % 1024)) * 10 + 1024/2) / 1024;
66			val /= 1024;
67		}
68		if (frac >= 10) {		/* We need to round up here. */
69			++val;
70			frac = 0;
71		}
72	}
73
74	/* If f==fmt then 'frac' and 'u' are ignored. */
75	snprintf(str, sizeof(str), f, val, frac, *u);
76
77	return str;
78}
79