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d877d44d12
the problems of the previous version (used floating point, overflowed, didn't round properly). The comments at the top of the file are worth reading; especially note 2 concerning "ls -sh".
90 lines
2.6 KiB
C
90 lines
2.6 KiB
C
/*
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* June 30, 2001 Manuel Novoa III
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*
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* All-integer version (hey, not everyone has floating point) of
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* make_human_readable_str, modified from similar code I had written
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* for busybox several months ago.
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*
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* Notes:
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* 1) I'm using an unsigned long long to hold the product size * block_size,
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* as df (which calls this routine) could request a representation of a
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* partition size in bytes > max of unsigned long. If long longs aren't
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* available, it would be possible to do what's needed using polynomial
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* representations (say, powers of 1024) and manipulating coefficients.
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* The base ten "bytes" output could be handled similarly.
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*
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* 2) The output of "ls -sh" can be misaligned because this routine always
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* outputs a decimal point and a tenths digit when display_unit != 0.
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* Hence, it isn't uncommon for the returned string to have a length
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* of 5 or 6 instead of <= 4 (as assumed).
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*
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* It might be nice to add a flag to indicate no decimal digits in
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* that case. This could be either an additional parameter, or a
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* special value of display_unit. Such a flag would also be nice for du.
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*
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* Some code to omit the decimal point and tenths digit is sketched out
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* and "#if 0"'d below.
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*/
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#include <stdio.h>
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#include "libbb.h"
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const char *make_human_readable_str(unsigned long size,
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unsigned long block_size,
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unsigned long display_unit)
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{
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/* The code will adjust for additional (appended) units. */
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static const char zero_and_units[] = { '0', 0, 'k', 'M', 'G', 'T' };
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static const char fmt[] = "%Lu";
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static const char fmt_tenths[] = "%Lu.%d%c";
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static char str[21]; /* Sufficient for 64 bit unsigned integers. */
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unsigned long long val;
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int frac;
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const char *u;
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const char *f;
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u = zero_and_units;
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f = fmt;
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frac = 0;
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val = ((unsigned long long) size) * block_size;
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if (val == 0) {
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return u;
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}
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if (display_unit) {
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val += display_unit/2; /* Deal with rounding. */
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val /= display_unit; /* Don't combine with the line above!!! */
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} else {
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++u;
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while ((val >= KILOBYTE)
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&& (u < zero_and_units + sizeof(zero_and_units) - 1)) {
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f = fmt_tenths;
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++u;
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frac = ((((int)(val % KILOBYTE)) * 10) + (KILOBYTE/2)) / KILOBYTE;
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val /= KILOBYTE;
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}
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if (frac >= 10) { /* We need to round up here. */
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++val;
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frac = 0;
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}
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#if 0
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/* Sample code to omit decimal point and tenths digit. */
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if ( /* no_tenths */ 1 ) {
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if ( frac >= 5 ) {
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++val;
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}
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f = "%Lu%*c" /* fmt_no_tenths */ ;
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frac = 1;
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}
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#endif
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}
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/* If f==fmt then 'frac' and 'u' are ignored. */
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snprintf(str, sizeof(str), f, val, frac, *u);
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return str;
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}
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