fmt_util.rs

// Copyright 2023 The Jujutsu Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Common formatting helpers

/// Find the smallest binary prefix with which the whole part of `x` is at most
/// three digits, and return the scaled `x`, that prefix, and the associated
/// base-1024 exponent.
pub fn binary_prefix(x: f32) -> (f32, &'static str) {
    /// Binary prefixes in ascending order, starting with the empty prefix. The
    /// index of each prefix is the base-1024 exponent it represents.
    const TABLE: [&str; 9] = ["", "Ki", "Mi", "Gi", "Ti", "Pi", "Ei", "Zi", "Yi"];

    let mut i = 0;
    let mut scaled = x;
    while scaled.abs() >= 1000.0 && i < TABLE.len() - 1 {
        i += 1;
        scaled /= 1024.0;
    }
    (scaled, TABLE[i])
}