win32_filetime_to_rfc3339.zig

fn hns_from_filetime(filetime: win32.FILETIME) u64 {
    return @as(u64, filetime.dwLowDateTime) |
        (@as(u64, filetime.dwHighDateTime) << 32);
}
const TimeFmt = struct {
    hns: u64,
    pub fn format(
        self: TimeFmt,
        comptime fmt: []const u8,
        options: std.fmt.FormatOptions,
        writer: anytype,
    ) !void {
        _ = fmt;
        _ = options;
        const hns_per_s = std.time.ns_per_s / 100;
        const epoch_seconds = std.time.epoch.EpochSeconds{
            .secs = self.hns / hns_per_s - (-std.time.epoch.windows),
        };
        const sub_secs = self.hns % hns_per_s;
        const yd = epoch_seconds.getEpochDay().calculateYearDay();
        const md = yd.calculateMonthDay();
        const ds = epoch_seconds.getDaySeconds();
        try writer.print("{}-{}-{}T{:0>2}:{:0>2}:{:0>2}.{}", .{
            yd.year,
            @intFromEnum(md.month),
            md.day_index + 1,
            ds.getHoursIntoDay(),
            ds.getMinutesIntoHour(),
            ds.getSecondsIntoMinute(),
            sub_secs,
        });
    }
};