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//! `NcMetric`

use crate::{cstring_mut, rstring};

// TODO: clarify, update and visibilize doc-comments

/// Takes an arbitrarily large number, and prints it into a fixed-size buffer by
/// adding the necessary SI suffix.
///
/// Usually, pass a `|[IB]PREFIXSTRLEN+1|-sized` buffer to generate up to
/// `|[IB]PREFIXCOLUMNS|` columns' worth of EGCs. The characteristic can occupy
/// up through `|mult-1|` characters (3 for 1000, 4 for 1024).
/// The mantissa can occupy either zero or two characters.
///
/// Floating-point is never used, because an IEEE758 double can only losslessly
/// represent integers through 2^53-1.
///
/// 2^64-1 is 18446744073709551615, 18.45E(xa). KMGTPEZY thus suffice to handle
/// an 89-bit uintmax_t. Beyond Z(etta) and Y(otta) lie lands unspecified by SI.
/// 2^-63 is 0.000000000000000000108, 1.08a(tto). val: value to print decimal:
/// scaling. '1' if none has taken place. buf: buffer in which string will be
/// generated omitdec: inhibit printing of all-0 decimal portions mult: base of
/// suffix system (almost always 1000 or 1024) uprefix: character to print
/// following suffix ('i' for kibibytes basically). only printed if suffix is
/// actually printed (input >= mult).
///
/// You are encouraged to consult notcurses_metric(3).
///
pub fn ncmetric(val: u64, decimal: u64, buf: &str, omitdec: i32, mult: u64, uprefix: i32) -> &str {
    let buf = cstring_mut![buf];
    rstring![crate::ffi::ncmetric(
        val, decimal, buf, omitdec, mult, uprefix
    )]
}

// The number of columns is one fewer, as the STRLEN expressions must leave
// an extra byte open in case 'µ' (U+00B5, 0xC2 0xB5) shows up.

// This is the true number of columns;
//
// to set up a printf()-style maximum field width,
// you should use [IB]PREFIXFMT (see below).
pub const NCMETRIC_PREFIXCOLUMNS: u32 = crate::bindings::ffi::PREFIXCOLUMNS;

// The maximum number of columns used by a mult == 1000 (standard)
// ncmetric() call.
pub const NCMETRIC_BPREFIXCOLUMNS: u32 = crate::bindings::ffi::BPREFIXCOLUMNS;

// IPREFIXCOLUMNS is the maximum number of columns used by a mult == 1024
// (digital information) ncmetric().
pub const NCMETRIC_IPREFIXCOLUMNS: u32 = crate::bindings::ffi::IPREFIXCOLUMNS;

//
// Does not include a '\0' (xxx.xxU)
pub const NCMETRIC_PREFIXSTRLEN: u32 = crate::bindings::ffi::PREFIXSTRLEN;

// The maximum number of columns used by a mult == 1024 call making use of
// the 'i' suffix.
// Does not include a '\0' (xxxx.xxUi), i == prefix
pub const NCMETRIC_BPREFIXSTRLEN: u32 = crate::bindings::ffi::BPREFIXSTRLEN;

// Does not include a '\0' (xxxx.xxU)
pub const NCMETRIC_IPREFIXSTRLEN: u32 = crate::bindings::ffi::IPREFIXSTRLEN;

// TODO:?
// WCHAR_MAX_UTF8BYTES