Compiler Explorer

Source code

// Constants for epoch difference and conversion
// EPOCH_DIFFERENCE is the number of seconds between the Windows epoch (1601-01-01)
// and the Unix epoch (1970-01-01)
const EPOCH_DIFFERENCE: i64 = 11_644_473_600;
const NANOS_PER_SEC: i64 = 1_000_000_000;
const WINDOWS_TICK: i64 = 100; // 100 nanoseconds

/// Converts a Unix timespec (seconds and nanoseconds) to a Windows timestamp
/// (100-nanosecond intervals since January 1, 1601 UTC)
///
/// This function handles both positive and negative timestamps, accounting for the difference
/// between Unix epoch (1970-01-01) and Windows epoch (1601-01-01).
///
/// Note: This function does not perform explicit overflow checks for performance reasons.
/// It should handle most practical timestamp values, but extreme values may cause overflow.
///
/// # Arguments
///
/// * `seconds` - Signed seconds since Unix epoch (January 1, 1970)
/// * `nanoseconds` - Additional nanoseconds (always non-negative)
///
/// # Returns
///
/// The Windows timestamp as an i64
#[no_mangle]
pub fn timespec_to_windows_timestamp(seconds: i64, nanoseconds: u32) -> i64 {
    // Convert seconds to Windows ticks
    let second_ticks = seconds * (NANOS_PER_SEC / WINDOWS_TICK);

// Convert nanoseconds to Windows ticks
    let nano_ticks = (nanoseconds as i64) / WINDOWS_TICK;

// Add epoch difference in ticks
    let epoch_diff_ticks = EPOCH_DIFFERENCE * (NANOS_PER_SEC / WINDOWS_TICK);

// Combine all components
    second_ticks + nano_ticks + epoch_diff_ticks
}