Data forwarding device and data forwarding method

Abstract

The purpose is to perform data transfer at high speed when the entire descriptor chain cannot be transferred by one activation. In the DMA control device (100), if the transfer start signal (16) is set to be valid, the descriptor information control unit (120) sequentially reads the descriptor information from the descriptor information storage unit (110), and reads When the number of retrieved descriptor information is equal to the number of transferable frames (17), the backward skip control unit (131) outputs a backward skip instruction (18). When the backward skip instruction (18) is output, the descriptor information control unit (120) skips reading of the rest of the descriptor information.

Description

technical field

[0001] The present invention relates to a DMA (Direct Memory Access) control device capable of forwarding multi-frame data with one forwarding start by creating a descriptor chain. Background technique

[0002] In the case of compiling a descriptor chain and performing DMA forwarding, the descriptor information is usually preset in the register or memory, the control circuit reads the descriptor information, and performs DMA forwarding according to the read descriptor information . The descriptor information includes information such as the starting address of the forwarding source, the forwarding frame size, the next descriptor number (address), and the end descriptor flag.

[0003] When performing DMA transfer, when the number of frames that can be transferred by one activation is limited, the entire descriptor chain may not be transferred by one activation.

[0004] Patent Document 1 describes that a 1-bit value indicating whether to perform DMA transfer...

Examples

Embodiment approach 1

[0026] In Embodiment 1, a description will be given of the DMA control device 100 which, when reading the descriptor information corresponding to the number of frames that can be transferred, skips and does not read the descriptors of subsequent frames. information.

[0027] figure 1 It is a block diagram showing the functions of the DMA control device 100 (data transfer device) according to the first embodiment.

[0028] The DMA control device 100 includes a descriptor information storage unit 110 , a descriptor information control unit 120 (descriptor information reading unit), a transfer determination unit 130 , and a data transfer unit 140 . In addition, the transfer determination unit 130 has a backward skip control unit 131 .

[0029] The descriptor information storage unit 110 is a memory for storing descriptor information including a start address of a forwarding source, a forwarding frame size, a next descriptor number (address), a forwarding completion flag indicat...

Embodiment approach 2

[0049]In Embodiment 2, the DMA control apparatus 100 which skips and does not read the descriptor information of the frame transferred up to the time of the previous start-up will be demonstrated.

[0050] image 3 It is a block diagram showing the functions of the DMA control device 100 according to the second embodiment.

[0051] image 3 The DMA control device 100 shown with figure 1 The difference between the illustrated DMA control device 100 is that the transfer determination unit 130 has a forward skip control unit 132 but does not have a backward skip control unit 131 .

[0052] The forward skip control unit 132 counts the number of descriptor information read by the descriptor information control unit 120 (that is, the number of frames to be transferred) immediately after the transfer start signal 16 is asserted. If the number of descriptor information read out is consistent with the forwardable frame number 17 declared by the CPU, the forward skip control unit 132...

Embodiment approach 3

[0063] In Embodiment 3, a DMA control device 100 having the functions of both Embodiments 1 and 2 will be described.

[0064] Figure 5 It is a block diagram showing the functions of the DMA control device 100 according to the third embodiment.

[0065] Figure 5 The DMA control device 100 shown with figure 1 The difference between the illustrated DMA control device 100 is that the forwarding determination unit 130 has the forward and backward skip control unit 133 and does not have the backward skip control unit 131 .

[0066] The forward and backward skip control unit 133 counts the number of descriptor information read by the descriptor information control unit 120 (that is, the number of frames to be transferred) immediately after the transfer enable signal 16 is asserted. If the number of read descriptor information matches the number of transferable frames 17 declared by the CPU, the forward and backward skip control unit 133 enables the backward skip instruction 18 f...

technical field

[0001] The present invention relates to a DMA (Direct Memory Access) control device capable of forwarding multi-frame data with one forwarding start by creating a descriptor chain. Background technique

[0002] In the case of compiling a descriptor chain and performing DMA forwarding, the descriptor information is usually preset in the register or memory, the control circuit reads the descriptor information, and performs DMA forwarding according to the read descriptor information . The descriptor information includes information such as the starting address of the forwarding source, the forwarding frame size, the next descriptor number (address), and the end descriptor flag.

[0003] When performing DMA transfer, when the number of frames that can be transferred by one activation is limited, the entire descriptor chain may not be transferred by one activation.

[0004] Patent Document 1 describes that a 1-bit value indicating whether to perform DMA transfer...

Examples

Embodiment approach 1

[0026] In Embodiment 1, a description will be given of the DMA control device 100 which, when reading the descriptor information corresponding to the number of frames that can be transferred, skips and does not read the descriptors of subsequent frames. information.

[0027] figure 1 It is a block diagram showing the functions of the DMA control device 100 (data transfer device) according to the first embodiment.

[0028] The DMA control device 100 includes a descriptor information storage unit 110 , a descriptor information control unit 120 (descriptor information reading unit), a transfer determination unit 130 , and a data transfer unit 140 . In addition, the transfer determination unit 130 has a backward skip control unit 131 .

[0029] The descriptor information storage unit 110 is a memory for storing descriptor information including a start address of a forwarding source, a forwarding frame size, a next descriptor number (address), a forwarding completion flag indicat...

Embodiment approach 2

[0049]In Embodiment 2, the DMA control apparatus 100 which skips and does not read the descriptor information of the frame transferred up to the time of the previous start-up will be demonstrated.

[0050] image 3 It is a block diagram showing the functions of the DMA control device 100 according to the second embodiment.

[0051] image 3 The DMA control device 100 shown with figure 1 The difference between the illustrated DMA control device 100 is that the transfer determination unit 130 has a forward skip control unit 132 but does not have a backward skip control unit 131 .

[0052] The forward skip control unit 132 counts the number of descriptor information read by the descriptor information control unit 120 (that is, the number of frames to be transferred) immediately after the transfer start signal 16 is asserted. If the number of descriptor information read out is consistent with the forwardable frame number 17 declared by the CPU, the forward skip control unit 132...

Embodiment approach 3

[0063] In Embodiment 3, a DMA control device 100 having the functions of both Embodiments 1 and 2 will be described.

[0064] Figure 5 It is a block diagram showing the functions of the DMA control device 100 according to the third embodiment.

[0065] Figure 5 The DMA control device 100 shown with figure 1 The difference between the illustrated DMA control device 100 is that the forwarding determination unit 130 has the forward and backward skip control unit 133 and does not have the backward skip control unit 131 .

[0066] The forward and backward skip control unit 133 counts the number of descriptor information read by the descriptor information control unit 120 (that is, the number of frames to be transferred) immediately after the transfer enable signal 16 is asserted. If the number of read descriptor information matches the number of transferable frames 17 declared by the CPU, the forward and backward skip control unit 133 enables the backward skip instruction 18 f...

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