Home
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
Utilities & Libraries
C Library Reference
N
nanospin_ns()
Busy-wait without blocking for a period of time

QNX Momentics IDE User's Guide
This User's Guide describes version 8.0 of the Integrated Development Environment (IDE) that's part of the QNX Tool Suite.
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
- Quickstart Guide
- System Architecture
  The System Architecture guide accompanies the QNX OS and is intended for both application developers and end-users.
- OS Components & Operations
- Graphics
- Programming
- System Security Guide
  The QNX System Security Guide is intended for both system integrators who are responsible for the security of a QNX OS system and developers who want to create a QNX OS resource manager free from vulnerabilities.
- Utilities & Libraries
  - C Library Reference
    - What's in a Function Description?
    - Manifests
    - Character Sets
    - A
    - B
    - C
    - D
    - E
    - F
    - G
    - H
    - I
    - J
    - K
    - L
    - M
    - N
      - name_attach()
        Register a name in the pathname space and create a channel
      - name_close()
        Close a server connection that was opened by name_open()
      - name_detach()
        Remove a name from the namespace and destroy the channel
      - name_open()
        Open a name to connect to a server
      - nan(), nanf(), nanl()
        Return a quiet NaN
      - nanosleep()
        Suspend a thread until a timeout or signal occurs
      - nanospin()
        Busy-wait without thread blocking for a period of time
      - nanospin_calibrate()
        Calibrate before calling nanospin*()
      - nanospin_count()
        Busy-wait without blocking for a number of iterations
      - nanospin_ns()
        Busy-wait without blocking for a period of time
      - nanospin_ns_to_count()
        Convert a time in nanoseconds into a number of iterations
      - ncurses
        Control a terminal's display
      - nearbyint(), nearbyintf(), nearbyintl()
        Return a rounded integer value
      - nextafter(), nextafterf(), nextafterl()
        Compute the next representable double-precision floating-point number
      - nexttoward(), nexttowardf(), nexttowardl()
        Compute the next representable floating-point number in a given direction
      - nftw(), nftw64()
        Walk a file tree
      - nice()
        Returns 0
      - nl_langinfo()
        Get information about the language or cultural area defined in the current locale
      - nrand48()
        Generate a pseudo-random nonnegative long integer in a thread-safe manner
      - nsec2timespec()
        Convert nanoseconds to a timespec structure
      - _NTO_TRACE_GET*(), _NTO_TRACE_SET*()
        Macros for working with the header of a trace event
    - O
    - P
    - Q
    - R
    - S
    - T
    - U
    - V
    - W
    - X
    - Y
    - Z
    - Full Safety Information
    - Glossary
  - Devctl and Ioctl Commands
  - JSON Library Reference
  - PAM Reference
  - QNX Helpers Developer's Guide
    These libraries provide QNX helpers, including helpers that assist with logging, string conversion, and number and type sizes.
  - SPI Framework Technote
  - Utilities Reference
  - WPA Control Interface Reference
    This document provides a reference for the Wi-Fi Protected Access (WPA) control interface, which provides a C API for the WPA/IEEE 802.11i protocols in Wi-Fi client stations. Application developers who want to control WPA operations and get associated status and event data should read this reference.
- Migrating to QNX OS 8.0
QNX Software in the Cloud
QNX Toolkit for Visual Studio Code
This User's Guide describes the QNX^® Toolkit for Visual Studio Code. The guide introduces you to the QNX Toolkit by explaining the QNX development environment and how to build, run, and debug your QNX^® Operating System (OS) applications and systems.
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation, explains how to obtain technical support, and provides some information about licensing.

nanospin_ns()

QNX SDP8.0C Library ReferenceAPIDeveloper

Busy-wait without blocking for a period of time

Synopsis:

#include <time.h>

int nanospin_ns( unsigned long nsec );

Arguments:

nsec: The number of nanoseconds that you want to busy-wait for.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The nanospin_ns() function busy-waits for the number of nanoseconds specified in nsec, without blocking the calling thread.

Note:

The nanospin*() functions are designed for use with hardware that requires short time delays between accesses. You should use them to delay only for times less than a few milliseconds. For longer delays, use the POSIX timer_*() functions.

Because of the nature of time measurement, the function might actually wait longer than the specified time. For more information, see the Understanding the Microkernel's Concept of Time chapter of the QNX OS Programmer's Guide.

Returns:

EOK: Success.
E2BIG: The delay specified by nsec is greater than 500 milliseconds.
Note:
A delay of more than a few milliseconds might not work on some processors. For longer delays, use the POSIX timer_*() functions.
ERANGE: The frequency of ClockCycles() is greater than 36 GHz and would cause problems with 64-bit math for larger spin times.

Classification:


Safety:
Cancellation point	No
Signal handler	Yes
Thread	Yes

Caveats:

You should use busy-waiting only when absolutely necessary for accessing hardware.

Page updated: August 09, 2024