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replace ActiveConfig with ActiveConfigNum.

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Add a Default() helper that simplifies setup for uncomplicated USB
devices.
This commit is contained in:
Sebastian Zagrodzki
2017-05-06 00:20:43 +02:00
parent 5200a36191
commit 9623c1ba8d
2 changed files with 30 additions and 9 deletions
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33
device.go
View File

@@ -88,9 +88,10 @@ func (d *Device) Reset() error {
return libusb.reset(d.handle)
}
// ActiveConfig returns the config id (not the index) of the active configuration.
// This corresponds to the ConfigInfo.Config field.
func (d *Device) ActiveConfig() (int, error) {
// ActiveConfigNum returns the config id of the active configuration.
// The value corresponds to the ConfigInfo.Config field of one of the
// ConfigInfos of this Device.
func (d *Device) ActiveConfigNum() (int, error) {
if d.handle == nil {
return 0, fmt.Errorf("ActiveConfig() called on %s after Close", d)
}
@@ -99,10 +100,11 @@ func (d *Device) ActiveConfig() (int, error) {
}
// Config returns a USB device set to use a particular config.
// The cfg provided is the config id (not the index) of the configuration to set,
// which corresponds to the ConfigInfo.Config field.
// The cfgNum provided is the config id (not the index) of the configuration to
// set, which corresponds to the ConfigInfo.Config field.
// USB supports only one active config per device at a time. Config claims the
// device before setting the desired config and keeps it locked until Close is called.
// device before setting the desired config and keeps it locked until Close is
// called.
func (d *Device) Config(cfgNum int) (*Config, error) {
if d.handle == nil {
return nil, fmt.Errorf("Config(%d) called on %s after Close", cfgNum, d)
@@ -125,6 +127,25 @@ func (d *Device) Config(cfgNum int) (*Config, error) {
return cfg, nil
}
// Default opens interface #0 with alternate setting #0 of the currently active
// config. It's intended as a shortcut for devices that have the simplest
// interface of a single config, interface and alternate setting.
func (d *Device) Default() (*Interface, error) {
cfgNum, err := d.ActiveConfigNum()
if err != nil {
return nil, fmt.Errorf("failed to get active config number of device %s: %v", d, err)
}
cfg, err := d.Config(cfgNum)
if err != nil {
return nil, fmt.Errorf("failed to claim config %d of device %s: %v", cfgNum, d, err)
}
intf, err := cfg.Interface(0, 0)
if err != nil {
return nil, fmt.Errorf("failed to select interface #%d alternate setting %d of config %d of device %s: %v", 0, 0, cfgNum, d, err)
}
return intf, nil
}
// Close closes the device.
func (d *Device) Close() error {
if d.handle == nil {

6
device_test.go
View File

@@ -47,10 +47,10 @@ func TestClaimAndRelease(t *testing.T) {
t.Fatalf("%s.Config(1): %v", dev, err)
}
defer cfg.Close()
if got, err := dev.ActiveConfig(); err != nil {
t.Errorf("%s.ActiveConfig(): got error %v, want nil", dev, err)
if got, err := dev.ActiveConfigNum(); err != nil {
t.Errorf("%s.ActiveConfigNum(): got error %v, want nil", dev, err)
} else if got != cfgNum {
t.Errorf("%s.ActiveConfig(): got %d, want %d", dev, got, cfgNum)
t.Errorf("%s.ActiveConfigNum(): got %d, want %d", dev, got, cfgNum)
}
intf, err := cfg.Interface(if1Num, alt1Num)