ryu/pretty/
mantissa.rs

1use crate::digit_table::DIGIT_TABLE;
2use core::ptr;
3
4#[cfg_attr(feature = "no-panic", inline)]
5pub unsafe fn write_mantissa_long(mut output: u64, mut result: *mut u8) {
6    if (output >> 32) != 0 {
7        // One expensive 64-bit division.
8        let mut output2 = (output - 100_000_000 * (output / 100_000_000)) as u32;
9        output /= 100_000_000;
10
11        let c = output2 % 10_000;
12        output2 /= 10_000;
13        let d = output2 % 10_000;
14        let c0 = (c % 100) << 1;
15        let c1 = (c / 100) << 1;
16        let d0 = (d % 100) << 1;
17        let d1 = (d / 100) << 1;
18        ptr::copy_nonoverlapping(
19            DIGIT_TABLE.as_ptr().offset(c0 as isize),
20            result.offset(-2),
21            2,
22        );
23        ptr::copy_nonoverlapping(
24            DIGIT_TABLE.as_ptr().offset(c1 as isize),
25            result.offset(-4),
26            2,
27        );
28        ptr::copy_nonoverlapping(
29            DIGIT_TABLE.as_ptr().offset(d0 as isize),
30            result.offset(-6),
31            2,
32        );
33        ptr::copy_nonoverlapping(
34            DIGIT_TABLE.as_ptr().offset(d1 as isize),
35            result.offset(-8),
36            2,
37        );
38        result = result.offset(-8);
39    }
40    write_mantissa(output as u32, result);
41}
42
43#[cfg_attr(feature = "no-panic", inline)]
44pub unsafe fn write_mantissa(mut output: u32, mut result: *mut u8) {
45    while output >= 10_000 {
46        let c = output - 10_000 * (output / 10_000);
47        output /= 10_000;
48        let c0 = (c % 100) << 1;
49        let c1 = (c / 100) << 1;
50        ptr::copy_nonoverlapping(
51            DIGIT_TABLE.as_ptr().offset(c0 as isize),
52            result.offset(-2),
53            2,
54        );
55        ptr::copy_nonoverlapping(
56            DIGIT_TABLE.as_ptr().offset(c1 as isize),
57            result.offset(-4),
58            2,
59        );
60        result = result.offset(-4);
61    }
62    if output >= 100 {
63        let c = (output % 100) << 1;
64        output /= 100;
65        ptr::copy_nonoverlapping(
66            DIGIT_TABLE.as_ptr().offset(c as isize),
67            result.offset(-2),
68            2,
69        );
70        result = result.offset(-2);
71    }
72    if output >= 10 {
73        let c = output << 1;
74        ptr::copy_nonoverlapping(
75            DIGIT_TABLE.as_ptr().offset(c as isize),
76            result.offset(-2),
77            2,
78        );
79    } else {
80        *result.offset(-1) = b'0' + output as u8;
81    }
82}
ryu/pretty/mantissa.rs

ryu/pretty/
mantissa.rs
