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    // Translated from C to Rust. The original C code can be found at
    // https://github.com/ulfjack/ryu and carries the following license:
    //
    // Copyright 2018 Ulf Adams
    //
    // The contents of this file may be used under the terms of the Apache License,
    // Version 2.0.
    //
    //    (See accompanying file LICENSE-Apache or copy at
    //     http://www.apache.org/licenses/LICENSE-2.0)
    //
    // Alternatively, the contents of this file may be used under the terms of
    // the Boost Software License, Version 1.0.
    //    (See accompanying file LICENSE-Boost or copy at
    //     https://www.boost.org/LICENSE_1_0.txt)
    //
    // Unless required by applicable law or agreed to in writing, this software
    // is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    // KIND, either express or implied.

    // Returns the number of decimal digits in v, which must not contain more than 9
    // digits.
    #[cfg_attr(feature = "no-panic", inline)]
    pub fn decimal_length9(v: u32) -> u32 {
        // Function precondition: v is not a 10-digit number.
        // (f2s: 9 digits are sufficient for round-tripping.)
        debug_assert!(v < 1000000000);

        if v >= 100000000 {
            9
        } else if v >= 10000000 {
            8
        } else if v >= 1000000 {
            7
        } else if v >= 100000 {
            6
        } else if v >= 10000 {
            5
        } else if v >= 1000 {
            4
        } else if v >= 100 {
            3
        } else if v >= 10 {
            2
        } else {
            1
        }
    }

    // Returns e == 0 ? 1 : [log_2(5^e)]; requires 0 <= e <= 3528.
    #[cfg_attr(feature = "no-panic", inline)]
    #[allow(dead_code)]
    pub fn log2_pow5(e: i32) -> i32 /* or u32 -> u32 */ {
        // This approximation works up to the point that the multiplication
        // overflows at e = 3529. If the multiplication were done in 64 bits, it
        // would fail at 5^4004 which is just greater than 2^9297.
        debug_assert!(e >= 0);
        debug_assert!(e <= 3528);
        ((e as u32 * 1217359) >> 19) as i32
    }

    // Returns e == 0 ? 1 : ceil(log_2(5^e)); requires 0 <= e <= 3528.
    #[cfg_attr(feature = "no-panic", inline)]
    pub fn pow5bits(e: i32) -> i32 /* or u32 -> u32 */ {
        // This approximation works up to the point that the multiplication
        // overflows at e = 3529. If the multiplication were done in 64 bits, it
        // would fail at 5^4004 which is just greater than 2^9297.
        debug_assert!(e >= 0);
        debug_assert!(e <= 3528);
        (((e as u32 * 1217359) >> 19) + 1) as i32
    }

    #[cfg_attr(feature = "no-panic", inline)]
    #[allow(dead_code)]
    pub fn ceil_log2_pow5(e: i32) -> i32 /* or u32 -> u32 */ {
        log2_pow5(e) + 1
    }

    // Returns floor(log_10(2^e)); requires 0 <= e <= 1650.
    #[cfg_attr(feature = "no-panic", inline)]
    pub fn log10_pow2(e: i32) -> u32 /* or u32 -> u32 */ {
        // The first value this approximation fails for is 2^1651 which is just greater than 10^297.
        debug_assert!(e >= 0);
        debug_assert!(e <= 1650);
        (e as u32 * 78913) >> 18
    }

    // Returns floor(log_10(5^e)); requires 0 <= e <= 2620.
    #[cfg_attr(feature = "no-panic", inline)]
    pub fn log10_pow5(e: i32) -> u32 /* or u32 -> u32 */ {
        // The first value this approximation fails for is 5^2621 which is just greater than 10^1832.
        debug_assert!(e >= 0);
        debug_assert!(e <= 2620);
        (e as u32 * 732923) >> 20
    }