avrdude/external/libhidapi/README.md

## HIDAPI library for Windows, Linux, FreeBSD and macOS

| CI instance          | Status |
|----------------------|--------|
| `macOS master`       | [![Build Status](https://travis-ci.org/libusb/hidapi.svg?branch=master)](https://travis-ci.org/libusb/hidapi) |
| `Windows master` | [![Build status](https://ci.appveyor.com/api/projects/status/r482aevuigmi86rk/branch/master?svg=true)](https://ci.appveyor.com/project/Youw/hidapi/branch/master) |
| `Linux/BSD, last build (branch/PR)` | [![builds.sr.ht status](https://builds.sr.ht/~qbicz/hidapi.svg)](https://builds.sr.ht/~qbicz/hidapi?) |

HIDAPI is a multi-platform library which allows an application to interface
with USB and Bluetooth HID-Class devices on Windows, Linux, FreeBSD, and macOS.
HIDAPI can be either built as a shared library (`.so`, `.dll` or `.dylib`) or
can be embedded directly into a target application by adding a single source
file (per platform) and a single header.

HIDAPI library was originally developed by Alan Ott ([signal11](https://github.com/signal11)).

It was moved to [libusb/hidapi](https://github.com/libusb/hidapi) on June 4th, 2019, in order to merge important bugfixes and continue development of the library.

## Table of Contents

* [About](#about)
* [What Does the API Look Like?](#what-does-the-api-look-like)
* [License](#license)
* [Download](#download)
* [Build Instructions](#build-instructions)
    * [Prerequisites](#prerequisites)
    * [Linux](#linux)
    * [FreeBSD](#freebsd)
    * [Mac](#mac)
    * [Windows](#windows)
    * [Building HIDAPI into a shared library on Unix Platforms](#building-hidapi-into-a-shared-library-on-unix-platforms)
    * [Building the manual way on Unix platforms](#building-the-manual-way-on-unix-platforms)
    * [Building on Windows](#building-on-windows)
* [Cross Compiling](#cross-compiling)
    * [Prerequisites](#prerequisites-1)
    * [Building HIDAPI](#building-hidapi)

## About

HIDAPI has five back-ends:
* Windows (using `hid.dll`)
* Linux/hidraw (using the Kernel's hidraw driver)
* Linux/libusb (using libusb-1.0)
* FreeBSD (using libusb-1.0)
* Mac (using IOHidManager)

On Linux, either the hidraw or the libusb back-end can be used. There are
tradeoffs, and the functionality supported is slightly different.

__Linux/hidraw__ (`linux/hid.c`):

This back-end uses the hidraw interface in the Linux kernel, and supports
both USB and Bluetooth HID devices. It requires kernel version at least 2.6.39
to build. In addition, it will only communicate with devices which have hidraw
nodes associated with them.
Keyboards, mice, and some other devices which are blacklisted from having
hidraw nodes will not work. Fortunately, for nearly all the uses of hidraw,
this is not a problem.

__Linux/FreeBSD/libusb__ (`libusb/hid.c`):

This back-end uses libusb-1.0 to communicate directly to a USB device. This
back-end will of course not work with Bluetooth devices.

HIDAPI also comes with a Test GUI. The Test GUI is cross-platform and uses
Fox Toolkit <http://www.fox-toolkit.org>.  It will build on every platform
which HIDAPI supports.  Since it relies on a 3rd party library, building it
is optional but recommended because it is so useful when debugging hardware.

## What Does the API Look Like?
The API provides the most commonly used HID functions including sending
and receiving of input, output, and feature reports. The sample program,
which communicates with a heavily hacked up version of the Microchip USB
Generic HID sample looks like this (with error checking removed for
simplicity):

**Warning: Only run the code you understand, and only when it conforms to the
device spec. Writing data at random to your HID devices can break them.**

```c
#ifdef WIN32
#include <windows.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include "hidapi.h"

#define MAX_STR 255

int main(int argc, char* argv[])
{
	int res;
	unsigned char buf[65];
	wchar_t wstr[MAX_STR];
	hid_device *handle;
	int i;

	// Initialize the hidapi library
	res = hid_init();

	// Open the device using the VID, PID,
	// and optionally the Serial number.
	handle = hid_open(0x4d8, 0x3f, NULL);

	// Read the Manufacturer String
	res = hid_get_manufacturer_string(handle, wstr, MAX_STR);
	wprintf(L"Manufacturer String: %s\n", wstr);

	// Read the Product String
	res = hid_get_product_string(handle, wstr, MAX_STR);
	wprintf(L"Product String: %s\n", wstr);

	// Read the Serial Number String
	res = hid_get_serial_number_string(handle, wstr, MAX_STR);
	wprintf(L"Serial Number String: (%d) %s\n", wstr[0], wstr);

	// Read Indexed String 1
	res = hid_get_indexed_string(handle, 1, wstr, MAX_STR);
	wprintf(L"Indexed String 1: %s\n", wstr);

	// Toggle LED (cmd 0x80). The first byte is the report number (0x0).
	buf[0] = 0x0;
	buf[1] = 0x80;
	res = hid_write(handle, buf, 65);

	// Request state (cmd 0x81). The first byte is the report number (0x0).
	buf[0] = 0x0;
	buf[1] = 0x81;
	res = hid_write(handle, buf, 65);

	// Read requested state
	res = hid_read(handle, buf, 65);

	// Print out the returned buffer.
	for (i = 0; i < 4; i++)
		printf("buf[%d]: %d\n", i, buf[i]);

	// Close the device
	hid_close(handle);

	// Finalize the hidapi library
	res = hid_exit();

	return 0;
}
```

You can also use [hidtest/test.c](hidtest/test.c)
as a starting point for your applications.


## License
HIDAPI may be used by one of three licenses as outlined in [LICENSE.txt](LICENSE.txt).

## Download
HIDAPI can be downloaded from GitHub
```sh
git clone git://github.com/libusb/hidapi.git
```

## Build Instructions

This section is long. Don't be put off by this. It's not long because it's
complicated to build HIDAPI; it's quite the opposite.  This section is long
because of the flexibility of HIDAPI and the large number of ways in which
it can be built and used.  You will likely pick a single build method.

HIDAPI can be built in several different ways. If you elect to build a
shared library, you will need to build it from the HIDAPI source
distribution.  If you choose instead to embed HIDAPI directly into your
application, you can skip the building and look at the provided platform
Makefiles for guidance.  These platform Makefiles are located in `linux/`,
`libusb/`, `mac/` and `windows/` and are called `Makefile-manual`.  In addition,
Visual Studio projects are provided.  Even if you're going to embed HIDAPI
into your project, it is still beneficial to build the example programs.


### Prerequisites:

#### Linux:
On Linux, you will need to install development packages for libudev,
libusb and optionally Fox-toolkit (for the test GUI). On
Debian/Ubuntu systems these can be installed by running:
```sh
sudo apt-get install libudev-dev libusb-1.0-0-dev libfox-1.6-dev
```

If you downloaded the source directly from the git repository (using
git clone), you'll need Autotools:
```sh
sudo apt-get install autotools-dev autoconf automake libtool
```

#### FreeBSD:
On FreeBSD you will need to install GNU make, libiconv, and
optionally Fox-Toolkit (for the test GUI). This is done by running
the following:
```sh
pkg_add -r gmake libiconv fox16
```

If you downloaded the source directly from the git repository (using
git clone), you'll need Autotools:
```sh
pkg_add -r autotools
```

#### Mac:
On Mac, you will need to install Fox-Toolkit if you wish to build
the Test GUI. There are two ways to do this, and each has a slight
complication. Which method you use depends on your use case.

If you wish to build the Test GUI just for your own testing on your
own computer, then the easiest method is to install Fox-Toolkit
using ports:
```sh
sudo port install fox
```

If you wish to build the TestGUI app bundle to redistribute to
others, you will need to install Fox-toolkit from source.  This is
because the version of fox that gets installed using ports uses the
ports X11 libraries which are not compatible with the Apple X11
libraries.  If you install Fox with ports and then try to distribute
your built app bundle, it will simply fail to run on other systems.
To install Fox-Toolkit manually, download the source package from
<http://www.fox-toolkit.org>, extract it, and run the following from
within the extracted source:
```sh
./configure && make && make install
```

#### Windows:
On Windows, if you want to build the test GUI, you will need to get
the `hidapi-externals.zip` package from the download site.  This
contains pre-built binaries for Fox-toolkit.  Extract
`hidapi-externals.zip` just outside of hidapi, so that
hidapi-externals and hidapi are on the same level, as shown:
```
     Parent_Folder
       |
       +hidapi
       +hidapi-externals
```
Again, this step is not required if you do not wish to build the
test GUI.


### Building HIDAPI into a shared library on Unix Platforms:

On Unix-like systems such as Linux, FreeBSD, macOS, and even Windows, using
MinGW or Cygwin, the easiest way to build a standard system-installed shared
library is to use the GNU Autotools build system.  If you checked out the
source from the git repository, run the following:

```sh
./bootstrap
./configure
make
make install # as root, or using sudo
```

If you downloaded a source package (i.e.: if you did not run git clone), you
can skip the `./bootstrap` step.

`./configure` can take several arguments which control the build. The two most
likely to be used are:
```sh
	--enable-testgui
		Enable build of the Test GUI. This requires Fox toolkit to
		be installed.  Instructions for installing Fox-Toolkit on
		each platform are in the Prerequisites section above.

	--prefix=/usr
		Specify where you want the output headers and libraries to
		be installed. The example above will put the headers in
		/usr/include and the binaries in /usr/lib. The default is to
		install into /usr/local which is fine on most systems.
```
### Building the manual way on Unix platforms:

Manual Makefiles are provided mostly to give the user and idea what it takes
to build a program which embeds HIDAPI directly inside of it. These should
really be used as examples only. If you want to build a system-wide shared
library, use the Autotools method described above.

To build HIDAPI using the manual Makefiles, change to the directory
of your platform and run make. For example, on Linux run:
```sh
cd linux/
make -f Makefile-manual
```

To build the Test GUI using the manual makefiles:
```sh
cd testgui/
make -f Makefile-manual
```

### Building on Windows:

To build the HIDAPI DLL on Windows using Visual Studio, build the `.sln` file
in the `windows/` directory.

To build the Test GUI on windows using Visual Studio, build the `.sln` file in
the `testgui/` directory.

To build HIDAPI using MinGW or Cygwin using Autotools, use the instructions
in the section [Building HIDAPI into a shared library on Unix Platforms](#building-hidapi-into-a-shared-library-on-unix-platforms)
above.  Note that building the Test GUI with MinGW or Cygwin will
require the Windows procedure in the [Prerequisites](#prerequisites-1) section
above (i.e.: `hidapi-externals.zip`).

To build HIDAPI using MinGW using the Manual Makefiles, see the section
[Building the manual way on Unix platforms](#building-the-manual-way-on-unix-platforms)
above.

HIDAPI can also be built using the Windows DDK (now also called the Windows
Driver Kit or WDK). This method was originally required for the HIDAPI build
but not anymore. However, some users still prefer this method. It is not as
well supported anymore but should still work. Patches are welcome if it does
not. To build using the DDK:

   1. Install the Windows Driver Kit (WDK) from Microsoft.
   2. From the Start menu, in the Windows Driver Kits folder, select Build
      Environments, then your operating system, then the x86 Free Build
      Environment (or one that is appropriate for your system).
   3. From the console, change directory to the `windows/ddk_build/` directory,
      which is part of the HIDAPI distribution.
   4. Type build.
   5. You can find the output files (DLL and LIB) in a subdirectory created
      by the build system which is appropriate for your environment. On
      Windows XP, this directory is `objfre_wxp_x86/i386`.

## Cross Compiling

This section talks about cross compiling HIDAPI for Linux using Autotools.
This is useful for using HIDAPI on embedded Linux targets.  These
instructions assume the most raw kind of embedded Linux build, where all
prerequisites will need to be built first.  This process will of course vary
based on your embedded Linux build system if you are using one, such as
OpenEmbedded or Buildroot.

For the purpose of this section, it will be assumed that the following
environment variables are exported.
```sh
$ export STAGING=$HOME/out
$ export HOST=arm-linux
```

`STAGING` and `HOST` can be modified to suit your setup.

### Prerequisites

Note that the build of libudev is the very basic configuration.

Build libusb. From the libusb source directory, run:
```sh
./configure --host=$HOST --prefix=$STAGING
make
make install
```

Build libudev. From the libudev source directory, run:
```sh
./configure --disable-gudev --disable-introspection --disable-hwdb \
	 --host=$HOST --prefix=$STAGING
make
make install
```

### Building HIDAPI

Build HIDAPI:
```
PKG_CONFIG_DIR= \
PKG_CONFIG_LIBDIR=$STAGING/lib/pkgconfig:$STAGING/share/pkgconfig \
PKG_CONFIG_SYSROOT_DIR=$STAGING \
./configure --host=$HOST --prefix=$STAGING
```