int

fn int(comptime T: type, value: []const u8) error{ NonCanonical, LargeValue }!T {
    const info = @typeInfo(T).int;
    if (info.bits % 8 != 0) @compileError("T must be byte aligned");

    if (value.len == 0) return error.NonCanonical;
    if (value.len >= 2) {
        if (value[0] == 0x00 and value[1] & 0x80 == 0) return error.NonCanonical;
        if (value[0] == 0xff and value[1] & 0x80 != 0) return error.NonCanonical;
    }

    const had_sign_byte = value.len >= 2 and value[0] == 0x00;
    const bytes = if (had_sign_byte) value[1..] else value;
    const der_negative = !had_sign_byte and bytes[0] & 0x80 != 0;

    switch (info.signedness) {
        .unsigned => {
            if (der_negative) return error.LargeValue;
            if (bytes.len > @sizeOf(T)) return error.LargeValue;
        },
        .signed => {
            const max_len: usize = if (had_sign_byte) @sizeOf(T) - 1 else @sizeOf(T);
            if (bytes.len > max_len) return error.LargeValue;
        },
    }

    var buf: [@sizeOf(T)]u8 = @splat(if (der_negative) 0xff else 0);
    @memcpy(buf[buf.len - bytes.len ..], bytes);
    return std.mem.readInt(T, &buf, .big);
}