Merge pull request #14 from nodtem66/master

Add OpenDeviceWithVidPid - thanks nodtem66!

README.md

@@ -7,8 +7,7 @@ Supported platforms include:
 
 - linux
 - darwin
-
-Windows support is unconfirmed, but should work via cgo and [libusb-win32](http://sourceforge.net/apps/trac/libusb-win32/wiki).
+- windows
 
 Contributing
 ============
@@ -19,8 +18,8 @@ You will need to send me the email address that you used to sign the agreement
 so that I can verify that it is on file before I can accept pull requests.
 
 
-Installation
-============
+Installation on Linux
+=====================
 
 Dependencies
 ------------
@@ -46,6 +45,42 @@ There is also a `usbid` package that will not be installed by default by this co
 
     go get -v github.com/kylelemons/gousb/usb{,id}
 
+Installation on Windows
+=======================
+Dependencies
+------------
+- Gcc (only tested on [Win-Builds](http://win-builds.org/), but any MSYS, CYGWIN, MINGW should be worked
+- [libusb-1.0](http://sourceforge.net/projects/libusb/files/libusb-1.0/)
+
+Build
+-----
+
+- After downloaded, extract them to some directory; such as D:\lib\libusb-1.0.xx\
+- Remember two path which "libusb.h" file and "libusb-1.0.a" inside
+
+*Note* For MinGW32, use **MinGW32/static/libusb-1.0.a** while MinGW64 use **MinGW64/static/libusb-1.0.a** for linker
+
+- Open `$(GOPATH)/src/github.com/kylelemons/gousb/usb/usb.go`. 
+
+Then edit `#cgo` directive, such as
+
+        // #cgo CFLAGS: -ID:/lib/libusbx-1.0.xx/include
+        // #cgo LDFLAGS: D:/lib/libusbx-1.0.xx/MinGW64/static/libusb-1.0.a
+
+
+to your `libusb-1.0` installed path before the line:
+
+    // #include <libusb-1.0/libusb.h>
+
+This flag will tell the linker the exact path of static library.
+Then install `gousb`:
+
+- Go to `$(GOPATH)/src/github.com/kylelemons/gousb/`. Run:
+
+        $ go install ./...
+		
+	`lsusb` can run under `$GOBIN/lsusb`
+
 Documentation
 =============
 The documentation can be viewed via local godoc or via Gary Burd's excellent [godoc.org](http://godoc.org/):

usb/device.go

@@ -203,3 +203,26 @@ found:
 
 	return end, nil
 }
+
+func (d *Device) GetStringDescriptor(desc_index int) (string, error) {
+
+	// allocate 200-byte array limited the length of string descriptor
+	goBuffer := make([]byte, 200)
+
+	// get string descriptor from libusb. if errno < 0 then there are any errors.
+	// if errno >= 0; it is a length of result string descriptor
+	errno := C.libusb_get_string_descriptor_ascii(
+		d.handle,
+		C.uint8_t(desc_index),
+		(*C.uchar)(unsafe.Pointer(&goBuffer[0])),
+		200)
+
+	// if any errors occur
+	if errno < 0 {
+		return "", fmt.Errorf("usb: getstr: %s", usbError(errno))
+	}
+	// convert slice of byte to string with limited length from errno
+	stringDescriptor := string(goBuffer[:errno])
+
+	return stringDescriptor, nil
+}

usb/device_test.go

@@ -0,0 +1,49 @@
+// Copyright 2013 Google Inc.  All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package usb_test
+
+import (
+	. "github.com/kylelemons/gousb/usb"
+	"testing"
+)
+
+func TestGetStringDescriptorAscii(t *testing.T) {
+	c := NewContext()
+	defer c.Close()
+	c.Debug(0)
+
+	devices, err := c.ListDevices(func(desc *Descriptor) bool {
+		return true
+	})
+	if err != nil {
+		t.Fatalf("%s", err.Error())
+	}
+
+	for i, d := range devices {
+
+		str, err := d.GetStringDescriptor(1)
+		if err != nil {
+			t.Fatalf("%s", err.Error())
+		}
+
+		str2, err := d.GetStringDescriptor(2)
+		if err != nil {
+			t.Fatalf("%s", err.Error())
+		}
+
+		t.Logf("%d: %s %s\n", i, str, str2)
+		d.Close()
+	}
+}

usb/usb.go

@@ -15,7 +15,10 @@
 // Package usb provides a wrapper around libusb-1.0.
 package usb
 
-// #cgo LDFLAGS: -lusb-1.0
+// #cgo windows CFLAGS: -ID:/lib/libusb-1.0.19/include
+// #cgo windows,amd64 LDFLAGS: D:/lib/libusb-1.0.19/MinGW64/static/libusb-1.0.a
+// #cgo windows,386 LDFLAGS: D:/lib/libusb-1.0.19/MinGW32/static/libusb-1.0.a
+// #cgo !windows LDFLAGS: -lusb-1.0
 // #include <libusb-1.0/libusb.h>
 import "C"
 
@@ -106,6 +109,31 @@ func (c *Context) ListDevices(each func(desc *Descriptor) bool) ([]*Device, erro
 	return ret, reterr
 }
 
+// OpenDeviceWithVidPid opens Device from specific VendorId and ProductId.
+// If there are any errors, it'll returns at second value.
+func (c *Context) OpenDeviceWithVidPid(vid, pid int) (*Device, error) {
+
+	handle := C.libusb_open_device_with_vid_pid(c.ctx, (C.uint16_t)(vid), (C.uint16_t)(pid))
+	if handle == nil {
+		return nil, ERROR_NOT_FOUND
+	}
+
+	dev := C.libusb_get_device(handle)
+	if dev == nil {
+		return nil, ERROR_NO_DEVICE
+	}
+
+	desc, err := newDescriptor(dev)
+
+	// return an error from nil-handle and nil-device
+	if err != nil {
+		return nil, err
+	}
+
+	device := newDevice(handle, desc)
+	return device, nil
+}
+
 func (c *Context) Close() error {
 	close(c.done)
 	if c.ctx != nil {

usb/usb_test.go

@@ -81,6 +81,46 @@ func TestEnum(t *testing.T) {
 	}
 }
 
+func TestOpenDeviceWithVidPid(t *testing.T) {
+	c := NewContext()
+	defer c.Close()
+	c.Debug(0)
+
+	// Accept for all device
+	devs, err := c.ListDevices(func(desc *Descriptor) bool {
+		return true
+	})
+	defer func() {
+		for _, d := range devs {
+			d.Close()
+		}
+	}()
+
+	if err != nil {
+		t.Fatalf("list: %s", err)
+	}
+
+	for i := range devs {
+		vid := devs[i].Vendor
+		pid := devs[i].Product
+		device, err := c.OpenDeviceWithVidPid((int)(vid), (int)(pid))
+
+		// if the context failed to open device
+		if err != nil {
+			t.Fail()
+		}
+
+		// if opened device was not valid
+		if device.Descriptor.Bus != devs[i].Bus ||
+			device.Descriptor.Address != devs[i].Address ||
+			device.Vendor != devs[i].Vendor ||
+			device.Product != devs[i].Product {
+			t.Fail()
+		}
+
+	}
+}
+
 func TestMultipleContexts(t *testing.T) {
 	var buf bytes.Buffer
 	log.SetOutput(&buf)