| 摘要 |
<p>A USB peripheral interface function (28), such as a modem (14), for scheduling communications from a host computer (12) over a communications facility is disclosed. A USB interface device (30) contains a shared memory (44) in which isochronous and bulk endpoints (240, 240') are established, and at which the message data are stored by the host computer (12) for transmission. Priority scheduling logic (137) in a transmit controller (132) selects which of the endpoints (240, 240') are to be accessed, for retrieval and transmission of the message data, according to a priority scheme. For connection-less communications, such as those according to IP protocols, a priority scheme is followed by the priority scheduling logic (137). For Asynchronous Transfer Mode (ATM) communications according to various Quality of Service (QoS) categories, isochronous endpoints (240') are associated with delay-sensitive messages such as those of the Constant Bit Rate (CBR) category, while bulk endpoints (240') are associated with non-delay-sensitive messages such as those of the Variable Bit Rate (VBR), Available Bit Rate (ABR), and Unspecified Bit Rate (UBR) categories. <IMAGE></p> |
