Scale integers from of larger size to integers of a smaller size

main.zig

const std = @import("std");
const maxInt = std.math.maxInt;

fn scaleInt(comptime DestType: type, val: anytype) DestType {
    if (@bitSizeOf(@TypeOf(val)) > 16) {
        @compileError("Function unsafe for values of bitsize greater than 16.");
    }
    const fv = @intToFloat(f32, val) / @intToFloat(f32, maxInt(@TypeOf(val))); // make ratio
    return @floatToInt(DestType, fv * maxInt(DestType) + 0.5);
}

pub fn main() void {
    std.log.info("{}", .{scaleInt(u3, @as(u8, 127))}); // output: 3
}