rust_assembler/stack_str/
usize_to_str.rs

1/// Formats a positive number into a `StackStr<N>`. The parameters required are the number that must be converted and the length of `N`, namely the number of digits of the given number, separated by a semicolon. In case the number has less digits than the specified length, it will have trailing zeros, represented as their utf-8 value: `48`. In case the length is less than required, it will result in undefined behavior.
2/// 
3/// # Examples
4/// 
5/// ```
6/// 
7/// assert_eq!("291", usize_to_str!(291; 3).str());
8/// assert_eq!("0291", usize_to_str!(291; 4).str());
9/// 
10/// ```
11/// 
12///  This function by default accepts values up to `u64`. If values up to `u128` are needed, as a third parameter specify bit_128.
13/// # Examples
14/// 
15/// ```
16/// 
17/// assert_eq!("000123714384710312239874874388", usize_to_str!(123714384710312239874874388; 30, bit_128).str());
18/// 
19/// ```
20#[macro_export]
21macro_rules! usize_to_str {
22    ( $n:expr; 1 ) => ({
23        let bytes = [$n | 48];
24
25        unsafe {
26            StackStr {
27                bytes,
28                str_: core::str::from_utf8_unchecked(&bytes)
29            }
30        }
31    });
32    ( $n:expr; 2 ) => ({
33        let tens_str_digit = ($n / 10) | 48;
34        let units_str_digit = ($n % 10) | 48;
35        let bytes = [tens_str_digit, units_str_digit];
36
37        unsafe {
38            StackStr {
39                bytes,
40                str_: core::str::from_utf8_unchecked(&bytes)
41            }
42        }
43    });
44    ( $n:expr; $len:expr ) => ({
45        let mut bytes = [0u8; $len];
46        let mut n = $n as u64;
47        let mut len = $len;
48
49        for byte in bytes.iter_mut() {
50            let divisor = 10_u64.pow(len - 1);
51
52            let str_digit = (n / divisor) | 48;
53            *byte = str_digit as u8;
54
55            n %= divisor;
56            len -= 1;
57
58        }
59
60        unsafe {
61            StackStr {
62                bytes,
63                str_: core::str::from_utf8_unchecked(&bytes)
64            }
65        }
66    });
67    ( $n:expr; $len:expr, bit_128 ) => ({
68        let mut bytes = [0u8; $len];
69        let mut n = $n;
70        let mut len = $len;
71
72        for byte in bytes.iter_mut() {
73            let divisor = 10_u128.pow(len - 1);
74
75            let str_digit = (n / divisor) | 48;
76            *byte = str_digit as u8;
77
78            n %= divisor;
79            len -= 1;
80
81        }
82
83        unsafe {
84            StackStr {
85                bytes,
86                str_: core::str::from_utf8_unchecked(&bytes)
87            }
88        }
89    })
90}
rust_assembler/stack_str/usize_to_str.rs

rust_assembler/stack_str/
usize_to_str.rs
