Provided by: libnotcurses-core-dev_3.0.7+dfsg.1-1ubuntu3_amd64 
NAME
notcurses_metric - fixed-width numeric output with metric suffixes
SYNOPSIS
#include <notcurses/notcurses.h>
#define NCPREFIXCOLUMNS 7
#define NCIPREFIXCOLUMNS 8
#define NCBPREFIXCOLUMNS 9
#define NCPREFIXSTRLEN (NCPREFIXCOLUMNS + 1)
#define NCIPREFIXSTRLEN (NCIPREFIXCOLUMNS + 1)
#define NCBPREFIXSTRLEN (NCBPREFIXCOLUMNS + 1)
#define NCMETRICFWIDTH(x, cols) ((int)(strlen(x) - ncstrwidth(x) + (cols)))
#define NCPREFIXFMT(x) NCMETRICFWIDTH((x), NCPREFIXCOLUMNS), (x)
#define NCIPREFIXFMT(x) NCMETRIXFWIDTH((x), NCIPREFIXCOLUMNS), (x)
#define NCBPREFIXFMT(x) NCMETRICFWIDTH((x), NCBPREFIXCOLUMNS), (x)
const char* ncnmetric(uintmax_t val, size_t s, uintmax_t decimal, char* buf, int omitdec,
unsigned mult, int uprefix);
static inline const char* ncqprefix(uintmax_t val, uintmax_t decimal, char* buf, int
omitdec);
static inline const char* nciprefix(uintmax_t val, uintmax_t decimal, char* buf, int
omitdec);
static inline const char* ncbprefix(uintmax_t val, uintmax_t decimal, char* buf, int
omitdec);
DESCRIPTION
ncmetric (and the helper wrappers qprefix and bprefix) accept very large (or very small)
non-negative numbers, and prepare formatted output of a maximum width using metric
suffixes. The suffix can represent arbitrary amounts of growth, but is designed for 1000
(NCPREFIX) or 1024 (NCIPREFIX). 1024 is used for "digital units of information", i.e.
kibibytes and gibibits. ncmetric supports the large suffixes KMGTPEZY (Kilo, Mega, Giga,
Tera, Peta, Exa, Zetta, and Yotta) and the small suffixes mµnpfazy (Milli, Micro, Nano,
Pico, Femto, Atto, Zepto, and Yocto). This covers the range 1e24 (one septillion) through
1e-24, sufficing for all possible values of a 64-bit uintmax_t.
val is the value being output, having been scaled by decimal. decimal will typically be
1; to represent values less than 1, decimal should be larger than val. The output will be
written to buf, which must be at least:
• NCPREFIXSTRLEN + 1 bytes for a 1000-based value
• NCIPREFIXSTRLEN + 1 bytes for a 1024-based value
• NCBPREFIXSTRLEN + 1 bytes for a 1024-based value with an 'i' suffix
s is the maximum output size, including '\0', used in the same fashion as snprintf(3)
(which ncnmetric calls).
Three helper functions are provided to simplify these common cases:
// Mega, kilo, gigafoo. Use NCPREFIXSTRLEN + 1 and NCPREFIXCOLUMNS.
static inline const char*
ncqprefix(uintmax_t val, uintmax_t decimal, char* buf, int omitdec){
return ncmetric(val, decimal, buf, omitdec, 1000, '\0');
}
// Mibi, kebi, gibibytes sans 'i' suffix. Use NCIPREFIXSTRLEN + 1.
static inline const char*
nciprefix(uintmax_t val, uintmax_t decimal, char* buf, int omitdec){
return ncmetric(val, decimal, buf, omitdec, 1024, '\0');
}
// Mibi, kebi, gibibytes. Use NCBPREFIXSTRLEN + 1 and NCBPREFIXCOLUMNS.
static inline const char*
ncbprefix(uintmax_t val, uintmax_t decimal, char* buf, int omitdec){
return ncmetric(val, decimal, buf, omitdec, 1024, 'i');
}
If omitdec is not zero, the decimal point and mantissa will be omitted if all digits to be
displayed would be zero. The decimal point takes the current locale into account (see
setlocale(3) and localeconv(3)). mult is the relative multiple for each suffix. uprefix,
if not zero, will be used as a suffix following any metric suffix.
The maximum number of columns is not directly related to the maximum number of bytes,
since Unicode doesn't necessarily map to single-byte characters (including the 'µ' micro
suffix). The corresponding defines for maximum column length are:
• NCPREFIXCOLUMNS (7)
• NCIPREFIXCOLUMNS (8)
• NCBPREFIXCOLUMNS (9)
In general, the maximum-width output will take the form CCC.mmMu, where C are digits of
the characteristic (up to ceil(log10(mult)) digits), the decimal point follows, m are
digits of the mantissa (up to 2), M is the metric suffix, and u is the uprefix. The
minimum-width output will take the form C. This minimal form can occur if omitdec is non-
zero and a single-column value such as 5 is passed for val.
Three more defines are provided to simplify formatted fixed-width output using the results
of ncmetric. Each of these macros accepts a character buffer holding the result of the
call, and expand to two arguments:
• NCPREFIXFMT(x)
• NCIPREFIXFMT(x)
• NCBPREFIXFMT(x)
These can be used in e.g. the following ungainly fashion:
**ncplane_printf(n, "%*s", NCPREFIXFMT(buf));**
to ensure that the output is always NCPREFIXCOLUMNS wide.
RETURN VALUES
NULL if input parameters were invalid. Otherwise, a pointer to buf, filled in with the
formatted output.
EXAMPLES
ncnmetric(0, INT_MAX, buf, 0, 1000, '\0'): "0.00".
ncnmetric(0, INT_MAX, buf, 1, 1000, '\0'): "0".
ncnmetric(1023, INT_MAX, buf, 1, 1000, '\0'): "1.02K".
ncnmetric(1023, INT_MAX, buf, 1, 1024, 'i'): "1023".
ncnmetric(1024, INT_MAX, buf, 1, 1024, 'i'): "1Ki".
ncnmetric(4096, INT_MAX, buf, 0, 1024, 'i'): "4.00Ki".
ncnmetric(0x7fffffffffffffff, INT_MAX, buf, 0, 1000, '\0'): "9.22E".
ncnmetric(0xffffffffffffffff, INT_MAX, buf, 0, 1000, '\0'): "18.45E".
BUGS
This function is difficult to understand.
SEE ALSO
localeconv(3), notcurses(3), notcurses_output(3), setlocale(3), snprintf(3)
AUTHORS
nick black <nickblack@linux.com>.
v3.0.7 notcurses_metric(3)