Function intRangeLessThan [src]

Returns an evenly distributed random integer at_least <= i < less_than. See uintLessThan, which this function uses in most cases, for commentary on the runtime of this function.

Prototype

pub fn intRangeLessThan(r: Random, comptime T: type, at_least: T, less_than: T) T

Parameters

r: RandomT: typeat_least: Tless_than: T

Source

  pub fn intRangeLessThan(r: Random, comptime T: type, at_least: T, less_than: T) T {
    assert(at_least < less_than);
    const info = @typeInfo(T).int;
    if (info.signedness == .signed) {
        // Two's complement makes this math pretty easy.
        const UnsignedT = std.meta.Int(.unsigned, info.bits);
        const lo: UnsignedT = @bitCast(at_least);
        const hi: UnsignedT = @bitCast(less_than);
        const result = lo +% r.uintLessThan(UnsignedT, hi -% lo);
        return @bitCast(result);
    } else {
        // The signed implementation would work fine, but we can use stricter arithmetic operators here.
        return at_least + r.uintLessThan(T, less_than - at_least);
    }
}  