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DMA-based data transfer method

A data transmission method and DMA controller technology, applied in the field of data transmission, can solve problems such as high data transmission efficiency and CPU interruption, and achieve the effect of avoiding low efficiency, avoiding performance degradation, and improving data transmission efficiency and performance

Active Publication Date: 2019-02-01
SHANGHAI UNITED IMAGING HEALTHCARE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the CPU can be freed to do other things during the data transmission process, the entire interaction process still involves CPU interrupts and DMA request interaction
For a large amount of data transmission, high data transmission efficiency is required, and interruption and interaction are performance bottlenecks

Method used

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Experimental program
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Embodiment Construction

[0028] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0029] image 3 It is a schematic diagram of the data transmission process based on DMA in the present invention.

[0030] See image 3 , the data transmission method based on DMA provided by the present invention comprises the following steps:

[0031] Step S1: Initialize the external device, and set the DMA operation buffer (ring buffer) for each external device and then start the DMA controller; the information of the initialized device includes: the physical memory start address DATA_BUFFER_START_ADDRESS used to store data during the DMA operation, The data buffer length DATA_BUFFER_LENGTH and the address offset value DATA_OFFSET_ADDRESS used to indicate that the device has written the data in the DMA operation buffer relative to DATA_BUFFER_START_ADDRESS. Turn on the DMA controller after initializing the device. Next, the mutual interaction bet...

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Abstract

The invention discloses a data transmission method based on DMA. The method comprises the steps that (a) external devices are initialized, a DMA operation buffering zone is set for each external device, and then a DMA controller is started; (b) each external device transmits data to the DMA operation buffering zone of itself through the DMA controller; (c) an application program acquires the data in the DMA operation buffering zone corresponding to each external device in a regular polling mode. According to the data transmission method based on DMA, whether DMA transmission is conducted is automatically and completely judged by the external devices, a CPU only needs to inquire whether data are available, and in this way, performance reduction caused by frequent interaction during traditional DMA data transmission is avoided, low efficiency caused by interaction interruption is avoided, and data transmission efficiency and performance are improved.

Description

technical field [0001] The invention relates to a data transmission method, in particular to a DMA-based data transmission method. Background technique [0002] DMA (Direct Memory Access, direct memory access) is an important feature of all modern computers, which allows hardware devices of different speeds to communicate without requiring a large amount of interrupt load depending on the CPU. [0003] DMA transfers copy data from one address space to another. When the CPU initiates the transfer action, the transfer action itself is implemented and completed by the DMA controller. A typical example is moving a block of external memory to a faster memory area inside the chip. Such an operation does not stall the processor work, but can be rescheduled to handle other work. [0004] When implementing DMA transmission, the DMA controller is directly in charge of the bus, so there is a problem of bus control right transfer. That is, before the DMA transfer, the CPU should hand...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06F13/28G06F12/08G06F12/0868
Inventor 曾群
Owner SHANGHAI UNITED IMAGING HEALTHCARE