File access method and device of SD (Secure Digital) card

A file reading and file technology, applied in the direction of input/output to record carrier, instrument, electrical digital data processing, etc., can solve the problems of discontinuity, resource occupation, memory address discontinuity, etc., to reduce resource occupation and improve speed Effect

Active Publication Date: 2010-11-03
中星智能系统技术有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The file access of the SD card is usually realized by DMA (direct memory access). It is known that a DMA transfer can only be performed for data that is physically continuously stored. However, in practice, the memory address corresponding to a file may It is discontinuous (such as the CPU memory address obtained by MMU mapping), or the cluster corresponding to a file in the SD card

Method used

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  • File access method and device of SD (Secure Digital) card
  • File access method and device of SD (Secure Digital) card
  • File access method and device of SD (Secure Digital) card

Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0069] Method Example 1:

[0070] reference figure 2 The flow chart of Embodiment 1 of an SD card file writing method is shown. The file writing involves a DMA transfer process of writing file data from a discontinuous memory address to a continuous physical cluster of the SD card. The embodiment may specifically include the following steps:

[0071] Step 201: Configure first file transfer information, where the first file transfer information includes: starting address and data length information of multiple pieces of file data in the memory, and information about consecutive physical clusters in the SD card;

[0072] Step 202: Read data of corresponding length from the multiple start addresses of the memory in sequence, and continuously write them into the continuous physical clusters of the SD card.

[0073] In practice, the file has an end identifier. In a preferred embodiment of the present invention, step 202 may specifically include the following sub-steps:

[0074] Sub-step S...

Example Embodiment

[0085] Method Example 2:

[0086] reference image 3 As shown in the flowchart of Embodiment 1 of a method for reading a file on an SD card, the file reading involves a DMA transfer process of writing file data from a continuous physical cluster of the SD card to a discontinuous memory address. This implementation The example can specifically include the following steps:

[0087] Step 301: Configure second file transfer information, where the second file transfer information includes: information about consecutive physical clusters in the SD card, and multiple pieces of address information in the memory;

[0088] Step 302: Extract data of corresponding lengths in consecutive physical clusters of the SD card in sequence, and write them into corresponding address segments in the memory respectively.

[0089] In practice, the file has an end identifier. In a preferred embodiment of the present invention, step 302 may specifically include the following sub-steps:

[0090] Sub-step S21, ac...

Example Embodiment

[0101] Method Example 3:

[0102] reference Figure 4 As shown in the flowchart of Embodiment 2 of an SD card file writing method, the file writing involves a DMA transfer process of writing file data from a continuous memory address to a discontinuous physical cluster group in the SD card. This embodiment may specifically include the following steps:

[0103] Step 401: Configure third file transfer information, where the third file transfer information includes: continuous address segment information in the memory and information about multiple physical cluster groups in the SD card;

[0104] Step 402: Extract data of corresponding lengths in consecutive address segments of the memory in sequence, and write them into corresponding physical cluster groups in the SD card.

[0105] In practice, the file has an end identifier. In a preferred embodiment of the present invention, step 402 may specifically include the following sub-steps:

[0106] Sub-step S31, according to the cluster numb...

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Abstract

The invention provides a file writing-in method of a SD (Secure Digital) card. The file writing-in process relates to a one-step DMA (Direct Memory Access) transmission process of wiring file data into a continuous physical cluster of the SD card from a discontinuous memory address. The method comprises the steps of: configuring first file transmission information, wherein the first file transmission information comprises initial addresses of multiple sections of file data in the memory and the information of the continuous physical cluster in the SD card; and sequentially reading data with corresponding length from the multiple sections of initial addresses of the memory, and continuously writing the data into the continuous physical cluster of the SD card. The invention can improve the direct memory access speed of the SD card and reduce the resource occupation of CPU (Central Processing Unit).

Description

technical field [0001] The invention relates to the field of data transmission control, in particular to a file reading method for an SD card, a file writing method for the SD card, a file reading device for the SD card, and a file writing device for the SD card. Background technique [0002] For a long time, SD cards (cards) with Flash Memory as storage bodies have been widely used in consumer electronic products due to their small size, low power consumption, rewritable and non-volatile characteristics. Especially in recent years, its range of applications has been increasing as prices have been falling and storage capacity has been increasing. [0003] Generally speaking, the SD card uses the FAT ((File Allocation Table, file allocation table) system to organize and manage the various files stored in it, and store the information related to the files in the FAT table for future access to files When used. The FAT table is a chain structure used for disk data (file) indexi...

Claims

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Application Information

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IPC IPC(8): G06F13/28G06F3/06
Inventor 艾国
Owner 中星智能系统技术有限公司
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