USB Config Descriptor -> Interface/Endpoint Descriptor

最新推荐文章于 2025-03-25 19:06:46 发布

转载最新推荐文章于 2025-03-25 19:06:46 发布 · 367 阅读

本文介绍了一个用于USB设备描述符解析的实现方案，包括配置描述符、接口描述符及端点描述符的设置方法。通过这些函数，可以将USB设备的各种描述符信息正确地解析并保存到内存中。

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USB_COMMON_DESCRIPTOR * USBH_X_GetNextDescriptor(
  USB_COMMON_DESCRIPTOR * pbCommDescriptor,
  U32 * wNextDescriptorOffset )
{
  USB_COMMON_DESCRIPTOR * pNextCommDescriptor;
  U8 bLength = pbCommDescriptor->bLength;
  *wNextDescriptorOffset += bLength;
  pNextCommDescriptor = (USB_COMMON_DESCRIPTOR *) ( ( (U8 *) pbCommDescriptor ) + bLength );
  return pNextCommDescriptor;
}

void USBH_X_SetEpDescriptor(
  TUSBH_X_DEVICE * pDevice,
  U8 bIfNumber,
  U8 bEpNumber,
  USB_ENDPOINT_DESCRIPTOR * pEpDescriptor )
{
  pDevice->pEndpointDescriptorArray[ bIfNumber ][ bEpNumber ] = pEpDescriptor;
}

void USBH_X_SetIfDescriptor(
  TUSBH_X_DEVICE * pDevice,
  U8 bIfNumber,
  USB_INTERFACE_DESCRIPTOR * pIfDescriptor )
{
  pDevice->pInterfaceDescriptorArray[ bIfNumber ] = pIfDescriptor;
}

void USBH_X_SetCfgDescriptor(
  TUSBH_X_DEVICE * pDevice )
{
  U32 interfaceIndex = 0;
  U32 endpointIndex = 0;

// Points to the current configuration descriptor
  USB_COMMON_DESCRIPTOR * pNextDescriptor;
  USB_CONFIGURATION_DESCRIPTOR * pCfgDescriptor;
  USB_INTERFACE_DESCRIPTOR * pIfDescriptor;
  USB_ENDPOINT_DESCRIPTOR * pEpDescriptor;

  pCfgDescriptor = (USB_CONFIGURATION_DESCRIPTOR*) ( ( pDevice->pUsbDevice->pConfigDescriptor ) );
  pNextDescriptor = (USB_COMMON_DESCRIPTOR*) ( pCfgDescriptor );

  U32 wTotalLength = pCfgDescriptor->wTotalLength;
  U32 wNextDescriptorOffset = USB_CONFIGURATION_DESCRIPTOR_LENGTH;

  pDevice->pCurrentConfigurationDescriptor = pCfgDescriptor;

  interfaceIndex = 0;
  while ( wNextDescriptorOffset < wTotalLength )
  {
    pNextDescriptor = USBH_X_GetNextDescriptor( pNextDescriptor, &wNextDescriptorOffset );
    if ( pNextDescriptor->bDescriptorType == USB_DESC_TYPE_INTERFACE )
    {
      pIfDescriptor = (USB_INTERFACE_DESCRIPTOR*) pNextDescriptor;
      if ( pIfDescriptor->bAlternateSetting == 0 )
      {
        USBH_X_SetIfDescriptor( pDevice, interfaceIndex, pIfDescriptor );
        // Parse Ep descriptors relative to the current interface
        endpointIndex = 0;
        while ( endpointIndex < pIfDescriptor->bNumEndpoints )
        {
          pNextDescriptor = USBH_X_GetNextDescriptor( pNextDescriptor, &wNextDescriptorOffset );
          if ( pNextDescriptor->bDescriptorType == USB_DESC_TYPE_ENDPOINT )
          {
            pEpDescriptor = (USB_ENDPOINT_DESCRIPTOR *) pNextDescriptor;
            USBH_X_SetEpDescriptor( pDevice, interfaceIndex, endpointIndex, pEpDescriptor );
            endpointIndex++;
            if ( ( endpointIndex == USBH_X_DEV_MAX_ENDPOINT )|| ( endpointIndex == pIfDescriptor->bNumEndpoints) )
break;
          }
        }

        interfaceIndex++;
        if ( ( interfaceIndex == USBH_X_DEV_MAX_IF )||( interfaceIndex == pDevice->pUsbDevice->InterfaceCount) )
          return;
      }
    }
  }
}

void USBH_X_SetDevDescriptor(
  TUSBH_X_DEVICE * pDevice )
{
  pDevice->pDeviceDescriptor = (USBH_DEVICE_DESCRIPTOR*) ( &( pDevice->pUsbDevice->DeviceDescriptor ) );
}