mirror of https://github.com/kidoman/embd
84 lines
2.0 KiB
Go
84 lines
2.0 KiB
Go
// Host descriptor data structures.
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package embd
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import (
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"errors"
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"fmt"
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"github.com/golang/glog"
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)
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// Descriptor represents a host descriptor.
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type Descriptor struct {
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GPIODriver func() GPIODriver
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I2CDriver func() I2CDriver
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LEDDriver func() LEDDriver
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SPIDriver func() SPIDriver
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}
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// The Describer type is a Descriptor provider.
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type Describer func(rev int) *Descriptor
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// Describers is a global list of registered host Describers.
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var describers = make(map[Host]Describer)
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// Register makes a host describer available by the provided host key.
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// If Register is called twice with the same host or if describer is nil,
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// it panics.
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func Register(host Host, describer Describer) {
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if describer == nil {
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panic("embd: describer is nil")
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}
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if _, dup := describers[host]; dup {
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panic("embd: describer already registered")
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}
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describers[host] = describer
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glog.V(1).Infof("embd: host %v is registered", host)
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}
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var hostOverride Host
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var hostRevOverride int
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var hostOverriden bool
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// SetHost overrides the host and revision no.
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func SetHost(host Host, rev int) {
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hostOverride = host
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hostRevOverride = rev
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hostOverriden = true
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}
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// DescribeHost returns the detected host descriptor.
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// Can be overriden by calling SetHost though.
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func DescribeHost() (*Descriptor, error) {
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var host Host
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var rev int
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if hostOverriden {
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host, rev = hostOverride, hostRevOverride
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} else {
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var err error
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host, rev, err = DetectHost()
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if err != nil {
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return nil, err
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}
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}
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describer, ok := describers[host]
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if !ok {
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return nil, fmt.Errorf("host: invalid host %q", host)
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}
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return describer(rev), nil
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}
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// ErrFeatureNotSupported is returned when the host does not support a
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// particular feature.
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var ErrFeatureNotSupported = errors.New("embd: requested feature is not supported")
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// ErrFeatureNotImplemented is returned when a particular feature is supported
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// by the host but not implemented yet.
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var ErrFeatureNotImplemented = errors.New("embd: requested feature is not implemented")
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