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
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131

// Copyright 2018 TiKV Project Authors. Licensed under Apache-2.0.

use crate::codec::{Error, Result};

/// `div_i64` divides i64 a with b and returns:
/// - an Error indicating overflow occurred or the divisor is 0
//. - i64 otherwise
#[inline]
pub fn div_i64(a: i64, b: i64) -> Result<i64> {
    if b == 0 {
        return Err(Error::division_by_zero());
    }
    match a.overflowing_div(b) {
        (_res, true) => Err(Error::overflow(
            "UNSIGNED BIGINT",
            &format!("({} / {})", a, b),
        )),
        (res, false) => Ok(res),
    }
}

/// `div_u64_with_i64` divides u64 a with i64 b and returns:
/// - an Error indicating overflow occurred or the divisor is 0
/// - u64 otherwise
#[inline]
pub fn div_u64_with_i64(a: u64, b: i64) -> Result<u64> {
    if b == 0 {
        return Err(Error::division_by_zero());
    }
    if b < 0 {
        if a != 0 && (b.overflowing_neg().0 as u64) <= a {
            Err(Error::overflow(
                "UNSIGNED BIGINT",
                &format!("({} / {})", a, b),
            ))
        } else {
            Ok(0)
        }
    } else {
        Ok(a / b as u64)
    }
}

/// `div_i64_with_u64` divides i64 a with u64 b and returns:
/// - an Error indicating overflow occurred or the divisor is 0
/// - u64 otherwise
#[inline]
pub fn div_i64_with_u64(a: i64, b: u64) -> Result<u64> {
    if b == 0 {
        return Err(Error::division_by_zero());
    }
    if a < 0 {
        if a.overflowing_neg().0 as u64 >= b {
            Err(Error::overflow(
                "UNSIGNED BIGINT",
                &format!("({} / {})", a, b),
            ))
        } else {
            Ok(0)
        }
    } else {
        Ok(a as u64 / b)
    }
}

#[cfg(test)]
mod tests {
    use crate::codec::error::{ERR_DATA_OUT_OF_RANGE, ERR_DIVISION_BY_ZERO};
    use std::{i64, u64};

    macro_rules! do_test {
        ($cases:ident, $func:ident) => {
            for (lsh, rsh, exp, is_overflow) in $cases {
                let desc = format!("Error testing {}({}, {})", stringify!($func), lsh, rsh);
                match super::$func(lsh, rsh) {
                    Ok(res) => {
                        assert!(!is_overflow, "{}: overflowed unexpectedly", desc);
                        assert_eq!(res, exp, "{}: expect {} but got {}", desc, exp, res);
                    }
                    Err(e) => {
                        assert!(is_overflow, "{}: expect overflow", desc);
                        assert_eq!(e.code(), ERR_DATA_OUT_OF_RANGE);
                    }
                }
            }
        };
    }

    #[test]
    fn test_div() {
        let div_i64_cases: Vec<(i64, i64, i64, bool)> = vec![
            (i64::MAX, 1, i64::MAX, false),
            (i64::MIN, 1, i64::MIN, false),
            (i64::MIN, -1, 0, true),
            (i64::MAX, -1, -i64::MAX, false),
            (1, -1, -1, false),
            (-1, 1, -1, false),
            (-1, 2, 0, false),
            (i64::MIN, 2, i64::MIN / 2, false),
        ];
        do_test!(div_i64_cases, div_i64);

        let div_u64_with_i64_cases: Vec<(u64, i64, u64, bool)> = vec![
            (0, -1, 0, false),
            (1, -1, 0, true),
            (i64::MAX as u64, i64::MIN, 0, false),
            (i64::MAX as u64, -1, 0, true),
        ];
        do_test!(div_u64_with_i64_cases, div_u64_with_i64);

        let div_i64_with_u64_cases: Vec<(i64, u64, u64, bool)> = vec![
            (i64::MIN, i64::MAX as u64, 0, true),
            (0, 1, 0, false),
            (-1, i64::MAX as u64, 0, false),
        ];
        do_test!(div_i64_with_u64_cases, div_i64_with_u64);

        assert_eq!(
            super::div_i64(0, 0).unwrap_err().code(),
            ERR_DIVISION_BY_ZERO
        );
        assert_eq!(
            super::div_u64_with_i64(0, 0).unwrap_err().code(),
            ERR_DIVISION_BY_ZERO
        );
        assert_eq!(
            super::div_i64_with_u64(0, 0).unwrap_err().code(),
            ERR_DIVISION_BY_ZERO
        );
    }
}