ACPI_USEC_PER_MSEC
acpi_os_stall(ACPI_USEC_PER_MSEC);
usleep(10 * ACPI_USEC_PER_MSEC); /* ten milliseconds */
usleep(ACPI_USEC_PER_MSEC); /* one millisecond */
usleep((milliseconds % ACPI_MSEC_PER_SEC) * ACPI_USEC_PER_MSEC);