Modify EndpointInfo to provide meaningful data rather than raw USB
descriptor values. E.g. for the user, the distinction between MaxIsoPkt and MaxPktSize is irrelevant, only the calculated max packet size matters.
This commit is contained in:
Sebastian Zagrodzki
@@ -36,6 +36,74 @@ type libusbDevice C.libusb_device
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type libusbDevHandle C.libusb_device_handle
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type libusbTransfer C.struct_libusb_transfer
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type libusbIso C.struct_libusb_iso_packet_descriptor
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type libusbEndpoint C.struct_libusb_endpoint_descriptor
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func (ep libusbEndpoint) endpointInfo(dev *Descriptor) EndpointInfo {
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ei := EndpointInfo{
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Number: uint8(ep.bEndpointAddress & EndpointNumMask),
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Direction: EndpointDirection(ep.bEndpointAddress & EndpointDirectionMask),
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TransferType: TransferType(ep.bmAttributes & TransferTypeMask),
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MaxPacketSize: uint32(ep.wMaxPacketSize),
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}
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if ei.TransferType == TransferTypeIsochronous {
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// bits 0-10 identify the packet size, bits 11-12 are the number of additional transactions per microframe.
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// Don't use libusb_get_max_iso_packet_size, as it has a bug where it returns the same value
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// regardless of alternative setting used, where different alternative settings might define different
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// max packet sizes.
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// See http://libusb.org/ticket/77 for more background.
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ei.MaxPacketSize = uint32(ep.wMaxPacketSize) & 0x07ff * (uint32(ep.wMaxPacketSize)>>11&3 + 1)
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ei.IsoSyncType = IsoSyncType(ep.bmAttributes & IsoSyncTypeMask)
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switch ep.bmAttributes & UsageTypeMask {
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case C.LIBUSB_ISO_USAGE_TYPE_DATA:
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ei.UsageType = IsoUsageTypeData
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case C.LIBUSB_ISO_USAGE_TYPE_FEEDBACK:
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ei.UsageType = IsoUsageTypeFeedback
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case C.LIBUSB_ISO_USAGE_TYPE_IMPLICIT:
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ei.UsageType = IsoUsageTypeImplicit
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}
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}
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// TODO(sebek): PollInterval does not work yet. The meaning of bInterval
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// in the descriptor varies depending on the device and USB version:
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// - if the device conforms to USB1.x:
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// Interval for polling endpoint for data transfers. Expressed in
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// milliseconds.
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// This field is ignored for bulk and control endpoints. For
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// isochronous endpoints this field must be set to 1. For interrupt
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// endpoints, this field may range from 1 to 255.
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// - if the device conforms to USB[23].x and the device is in low speed
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// of full speed mode:
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// Interval for polling endpoint for data transfers. Expressed in
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// frames or microframes depending on the device operating speed
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// (i.e., either 1 millisecond or 125 µs units).
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// For full-/high-speed isochronous endpoints, this value must be in
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// the range from 1 to 16. The bInterval value is used as the exponent
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// for a 2bInterval-1 value; e.g., a bInterval of 4 means a period
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// of 8 (24-1).
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// For full-/low-speed interrupt endpoints, the value of this field may
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// be from 1 to 255.
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// For high-speed interrupt endpoints, the bInterval value is used as
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// the exponent for a 2bInterval-1 value; e.g., a bInterval of 4 means
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// a period of 8 (24-1). This value must be from 1 to 16.
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// For high-speed bulk/control OUT endpoints, the bInterval must
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// specify the maximum NAK rate of the endpoint. A value of 0 indicates
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// the endpoint never NAKs. Other values indicate at most 1 NAK each
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// bInterval number of microframes. This value must be in the range
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// from 0 to 255.
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// - if the device conforms to USB3.x and the device is in SuperSpeed mode:
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// Interval for servicing the endpoint for data transfers. Expressed in
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// 125-µs units.
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// For Enhanced SuperSpeed isochronous and interrupt endpoints, this
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// value shall be in the range from 1 to 16. However, the valid ranges
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// are 8 to 16 for Notification type Interrupt endpoints. The bInterval
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// value is used as the exponent for a 2(bInterval-1) value; e.g., a
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// bInterval of 4 means a period of 8 (2(4-1) → 23 → 8).
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// This field is reserved and shall not be used for Enhanced SuperSpeed
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// bulk or control endpoints.
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//
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// Note: in low-speed mode, isochronous transfers are not supported.
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ei.PollInterval = 0
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return ei
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}
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// libusbIntf is a set of trivial idiomatic Go wrappers around libusb C functions.
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// The underlying code is generally not testable or difficult to test,
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@@ -70,7 +138,7 @@ type libusbIntf interface {
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setAlt(*libusbDevHandle, uint8, uint8) error
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// transfer
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alloc(*libusbDevHandle, uint8, TransferType, time.Duration, int, []byte) (*libusbTransfer, error)
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alloc(*libusbDevHandle, *EndpointInfo, time.Duration, int, []byte) (*libusbTransfer, error)
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cancel(*libusbTransfer) error
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submit(*libusbTransfer, chan struct{}) error
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data(*libusbTransfer) (int, TransferStatus)
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@@ -184,24 +252,9 @@ func (libusbImpl) getDeviceDesc(d *libusbDevice) (*Descriptor, error) {
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Cap: int(alt.bNumEndpoints),
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}
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i.Endpoints = make([]EndpointInfo, 0, len(ends))
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for _, end := range ends {
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ei := EndpointInfo{
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Address: uint8(end.bEndpointAddress),
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Attributes: uint8(end.bmAttributes),
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MaxPacketSize: uint16(end.wMaxPacketSize),
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PollInterval: uint8(end.bInterval),
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RefreshRate: uint8(end.bRefresh),
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SynchAddress: uint8(end.bSynchAddress),
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}
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if ei.TransferType() == TransferTypeIsochronous {
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// bits 0-10 identify the packet size, bits 11-12 are the number of additional transactions per microframe.
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// Don't use libusb_get_max_iso_packet_size, as it has a bug where it returns the same value
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// regardless of alternative setting used, where different alternative settings might define different
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// max packet sizes.
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// See http://libusb.org/ticket/77 for more background.
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ei.MaxIsoPacket = uint32(end.wMaxPacketSize) & 0x07ff * (uint32(end.wMaxPacketSize)>>11&3 + 1)
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}
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i.Endpoints = append(i.Endpoints, ei)
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for n, end := range ends {
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// TODO(sebek): pass the device descriptor too.
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i.Endpoints[n] = libusbEndpoint(end).endpointInfo(nil)
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}
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descs = append(descs, i)
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}
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@@ -313,15 +366,15 @@ func (libusbImpl) setAlt(d *libusbDevHandle, iface, setup uint8) error {
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return fromUSBError(C.libusb_set_interface_alt_setting((*C.libusb_device_handle)(d), C.int(iface), C.int(setup)))
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}
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func (libusbImpl) alloc(d *libusbDevHandle, addr uint8, tt TransferType, timeout time.Duration, isoPackets int, buf []byte) (*libusbTransfer, error) {
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func (libusbImpl) alloc(d *libusbDevHandle, ep *EndpointInfo, timeout time.Duration, isoPackets int, buf []byte) (*libusbTransfer, error) {
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xfer := C.libusb_alloc_transfer(C.int(isoPackets))
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if xfer == nil {
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return nil, fmt.Errorf("libusb_alloc_transfer(%d) failed", isoPackets)
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}
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xfer.dev_handle = (*C.libusb_device_handle)(d)
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xfer.endpoint = C.uchar(addr)
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xfer.endpoint = C.uchar(uint8(ep.Number&EndpointNumMask) | uint8(ep.Direction&EndpointDirectionMask))
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xfer.timeout = C.uint(timeout / time.Millisecond)
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xfer._type = C.uchar(tt)
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xfer._type = C.uchar(ep.TransferType)
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xfer.num_iso_packets = C.int(isoPackets)
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xfer.buffer = (*C.uchar)((unsafe.Pointer)(&buf[0]))
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xfer.length = C.int(len(buf))
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