src/pretty/exponent.rs


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48

use crate::digit_table::*;
use core::ptr;

#[cfg_attr(feature = "no-panic", inline)]
pub unsafe fn write_exponent3(mut k: isize, mut result: *mut u8) -> usize {
    let sign = k < 0;
    if sign {
        *result = b'-';
        result = result.offset(1);
        k = -k;
    }

    debug_assert!(k < 1000);
    if k >= 100 {
        *result = b'0' + (k / 100) as u8;
        k %= 100;
        let d = DIGIT_TABLE.get_unchecked(k as usize * 2);
        ptr::copy_nonoverlapping(d, result.offset(1), 2);
        sign as usize + 3
    } else if k >= 10 {
        let d = DIGIT_TABLE.get_unchecked(k as usize * 2);
        ptr::copy_nonoverlapping(d, result, 2);
        sign as usize + 2
    } else {
        *result = b'0' + k as u8;
        sign as usize + 1
    }
}

#[cfg_attr(feature = "no-panic", inline)]
pub unsafe fn write_exponent2(mut k: isize, mut result: *mut u8) -> usize {
    let sign = k < 0;
    if sign {
        *result = b'-';
        result = result.offset(1);
        k = -k;
    }

    debug_assert!(k < 100);
    if k >= 10 {
        let d = DIGIT_TABLE.get_unchecked(k as usize * 2);
        ptr::copy_nonoverlapping(d, result, 2);
        sign as usize + 2
    } else {
        *result = b'0' + k as u8;
        sign as usize + 1
    }
}