Application programming interface for data transfer and bus management over a bus structure

• US 20050097245A1
• Filed: 12/01/2004
• Published: 05/05/2005
• Est. Priority Date: 02/02/1996
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.), Sony Electronics Inc. (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.), Sony Electronics Inc. (Sony Group Corp.)
• Inventors: Shima, Hisato, Smyers, Scott, Lym, Kevin K., Fairman, Bruce A.
• Granted Patent: US 7,577,782 B2
• Time in Patent Office: Days
• US Class Current: 710/52
• CPC Class Codes: G06F 13/10 Program control for peripheral devices G06F13/14 - G06F13/42 take precedence
• CPC Class Codes: G06F 13/102 where the programme performs an interfacing function, e.g. device driver G06F13/105 takes precedence; scheduling within device drivers G06F9/52; contention policies within device drivers G06F9/4881
• CPC Class Codes: G06F 13/28 using burst mode transfer, e.g. direct memory access DMA, cycle steal G06F13/32 takes precedence
• CPC Class Codes: H04L 12/40058 Isochronous transmission
• CPC Class Codes: H04L 12/40065 Bandwidth and channel allocation home automation networks H04L12/2803; flow control H04L47/10
• CPC Class Codes: H04L 12/40123 Interconnection of computers and peripherals printer information exchange with computer G06F3/1293
• CPC Class Codes: H04L 49/90 Buffering arrangements
• CPC Class Codes: H04L 49/901 using storage descriptor, e.g. read or write pointers
• CPC Class Codes: H04L 69/32 Architecture of open systems interconnection [OSI] 7-layer type protocol stacks, e.g. the interfaces between the data link level and the physical level

Abstract

In a first embodiment, an applications programming interface (API) implements and manages isochronous and asynchronous data transfer operations between an application and a bus structure. During an synchronous transfer the API includes the ability to transfer any amount of data between one or more local data buffers within the application and a range of addresses over the bus structure using one or more asynchronous transactions. An automatic transaction generator may be used to automatically generate the transactions necessary to complete the data transfer. The API also includes the ability to transfer data between the application and another node on the bus structure isochronously over a dedicated channel. During an isochronous data transfer, a buffer management scheme is used to manage a linked list of data buffer descriptors. During isochronous transfers of data, the API provides implementation of a resynchronization event in the stream of data allowing for resynchronization by the application to a specific point within the data. Implementation is also provided for a callback routine for each buffer in the list which calls the application at a predetermined point during the transfer of data. An isochronous API of the preferred embodiment presents a virtual representation of a plug, using a plug handle, to the application. The isochronous API notifies a client application of any state changes on a connected plug through the event handle. The isochronous API also manages buffers utilized during a data operation by attaching and detaching the buffers to the connected plug, as appropriate, to manage the data flow.

Claims

1. An interface between an application and a bus structure for to manage data transfer operations between the application and the bus structure comprising:

a. an applications interface to communicate with the application to receive requests from and send instructions to the application;

b. a controller to control isochronous data transfer operations between the application and the bus structure including managing a linked list of buffer descriptors, each corresponding to and representing a buffer; and

c. a bus interface circuit to provide a physical interface to the bus structure to send and receive data packets over the bus structure.

128. The interface as claimed in claim 1 wherein the buffers are provided by the application.

129. The interface as claimed in claim 1 wherein the linked list includes a forward pointer for each buffer within the linked list.

130. The interface as claimed in claim 129 wherein the linked list further includes a backward pointer for each buffer within the linked list thereby making the list circular.

131. The interface as claimed in claim 1 wherein each of the buffer descriptors in the linked list include capability for a callback routine which is activated to call the application at a predetermined point during a data transfer operation.

132. The interface as claimed in claim 1 wherein each of the buffer descriptors included in the list include capability for a resynchronization event which is activated to resynchronize the application to a predetermined point during a data transfer operation.

133. The interface as claimed in claim 1 further comprising an automatic transaction generator for automatically generating transactions necessary to complete an asynchronous data transfer operation between a buffer assigned by the application and the bus structure.

134. The interface as claimed in claim 1 wherein the bus structure is an IEEE 1394 standard bus structure.

135. The interface as claimed in claim 1 wherein the linked list includes a forward pointer and a backward pointer for each buffer within the linked list thereby making the list linear.

2-127. -127. (canceled)

136. An interface between an application and an IEEE 1394 standard bus structure to manage data transfer operations between the application and the bus structure comprising:

a. an applications interface to communicate with the application to receive requests from and send instructions to the application;

b. a controller to control isochronous data transfer operations between the application and the bus structure including a linked list of buffers provided by the application; and

c. a bus interface circuit to provide a physical interface to the bus structure to send and receive data packets over the bus structure.

137. The interface as claimed in claim 136 wherein the linked list includes a forward pointer and a backward pointer for each buffer within the linked list thereby making the list circular.

138. The interface as claimed in claim 136 wherein each of the buffers in the linked list include capability for a callback routine which is activated to call the application at a predetermined point during a data transfer operation.

139. The interface as claimed in claim 136 wherein each of the buffers in the linked list include capability for a resynchronization event which is activated to resynchronize the application to a predetermined point during a data transfer operation.

140. The interface as claimed in claim 136 wherein the linked list includes a forward pointer and a backward pointer for each buffer within the linked list thereby making the list linear.

141. A buffer management method for handling data transmitted on an isochronous channel, the method comprising:

establishing a linked list of buffers for receiving isochronous data from a sender device;

receiving the isochronous data from the sender device;

loading the isochronous data into the linked list of buffers; and

accessing the data in the linked list of buffers for output to a client device.

142. The buffer management method as claimed in claim 141 wherein the data is transmitted between an application and a bus structure.

143. The buffer management method as claimed in claim 142 wherein during an isochronous send operation the application processes a buffer by loading data into the buffer.

144. The buffer management method as claimed in claim 142 wherein during an isochronous receive operation the application processes a buffer by obtaining data from the buffer.

145. The buffer management method as claimed in claim 142 wherein each of the buffers included in the linked list include capability for a callback routine which is activated to call the application at a predetermined point during a data transfer operation.

146. The buffer management method as claimed in claim 142 wherein each of the buffers included in the linked list include capability for a resynchronization event which is activated to resynchronize the application to a predetermined point during a data transfer operation.

147. A buffer management method for handling data transmitted on an isochronous channel, the method comprising:

establishing a linked list of buffers for receiving isochronous data from a sender device, each buffer comprising a forward pointer to the next buffer in the list and a backward pointer to the previous pointer in the list;

receiving the isochronous data from the sender device;

loading the isochronous data into the linked list of buffers; and

accessing the data in the linked list of buffers for output to a client device.

148. The buffer management method as claimed in claim 147 wherein the data is transmitted between an application and a bus structure.

149. The buffer management method as claimed in claim 148 wherein during an isochronous send operation the application processes a buffer by loading data into the buffer.

150. The buffer management method as claimed in claim 148 wherein during an isochronous receive operation the application processes a buffer by obtaining data from the buffer.

151. The buffer management method as claimed in claim 148 wherein each of the buffers included in the linked list include capability for a callback routine which is activated to call the application at a predetermined point during a data transfer operation.

152. The buffer management method as claimed in claim 148 wherein each of the buffers included in the linked list include capability for a resynchronization event which is activated to resynchronize the application to a predetermined point during a data transfer operation.

153. A computer readable medium having stored thereon a plurality of sequences of instructions including sequences of instructions which, when executed by a device including an application and within a network including a plurality of nodes interconnected by a plurality of point-to-point links forming a bus structure, cause the device to perform the steps of:

receiving a request for a data transfer operation from the application; and

managing a linked list of buffer descriptors each corresponding to a buffer provided by the application for completing the data transfer operation, wherein data is transferred between one buffer and the bus structure while the application processes another buffer.

154. A computer readable medium having stored thereon a plurality of sequences of instructions including sequences of instructions which, when executed by a device including an application and within a network including a plurality of nodes interconnected by a plurality of point-to-point links forming a bus structure, cause the device to perform the steps of:

establishing a linked list of buffers for receiving isochronous data from a sender device;

receiving the isochronous data from the sender device;

loading the isochronous data into the linked list of buffers; and

accessing the data in the linked list of buffers for output to a client device.