Method and device for calculating fixed point digital signal common function value

A digital signal and function value technology, which is applied in the field of fixed-point digital signal processing, can solve problems such as low accuracy, inability to accurately calculate common function values ​​of fixed-point digital signals, redundant table contents, etc. The effect of small value range and reduced space

Inactive Publication Date: 2007-04-11
VIMICRO CORP
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0020] To sum up, the existing method of using look-up tables to find common function values ​​has the disadvantages of low accuracy and redundant table content, and cannot accurately calculate the common function values ​​of fixed-point digital signals.

Method used

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  • Method and device for calculating fixed point digital signal common function value
  • Method and device for calculating fixed point digital signal common function value
  • Method and device for calculating fixed point digital signal common function value

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Embodiment 1

[0073] In this embodiment, the word length of the fixed-point digital signal is 16 bits, the number of low-order data bits to be discarded is 6, and the commonly used function is the square root function. In actual application, according to the different word lengths of the hardware platform implementing the technical solution of the present invention, the fixed-point digital signal word length may be 24bits, 32bits or other lengths, and the number of low-order data bits to be discarded may also vary depending on the specific application. It can be other values ​​depending on the different degree requirements, and it can be implemented only by adjusting the word length of the fixed-point digital signal and the number of low-order data bits to be discarded in this embodiment.

[0074] FIG. 2 is a flow chart of a method for calculating a common function value of a fixed-point digital signal in Embodiment 1 of the present invention. In this embodiment, the commonly used function ...

Embodiment 2

[0124] In this embodiment, the word length of the fixed-point digital signal is 16 bits, the number of data bits to be discarded is 5, and the common function is a natural logarithmic function with e as the base.

[0125] The method flowchart of finding natural logarithm function value in the present embodiment is identical with Fig. 2 in embodiment one, referring to Fig. 2, the present embodiment method comprises the following steps:

[0126] In step 201, according to the predetermined fixed-point digital signal word length, the number of low-order data bits to be discarded, and the type of commonly used functions, a corresponding relationship table between intermediate results and table look-up indexes is established, which is recorded as ln_table[]. In this embodiment, since the number of low-order data bits to be discarded is 5, the established ln-table[] needs 16-2-5=9bits, and there are 2 bits in the table. 9 = 512 elements.

[0127] The basis for determining the interm...

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Abstract

The invention discloses a method of seeking the common function of the fixed-point digital signal. This method is based on word length of the pre-determined fixed-point digital signal, the number of the low-order data which is prepared to abandon, and the type of commonly used functions to establish the corresponding relationship between the medium result and the index for looking up table, which includes the following steps: A. integrating the input data of the common function and gaining the integrated data, B. requiring the index according to the integrated data and obtaining the medium result according to the index and the relationship between pre-established medium result and index, C. calculating the common function of the input data according to medium results. The invention also discloses a device of seeking such common function. The application of this invention can improve the accuracy of the fixed-point digital signal processing, cut down the space of storing the corresponding relationship between the medium result and the index.

Description

technical field [0001] The invention relates to a fixed-point digital signal processing technology, in particular to a method and a device for calculating a common function value of a fixed-point digital signal. Background technique [0002] Digital signal processors can quickly implement various digital signal processing algorithms in real time, which provides great convenience for real-time signal processing. Digital signal processors can be divided into floating-point digital signal processors and fixed-point digital signal processors. Most fixed-point digital signal processors do not support the operation of directly calculating the value of a common function of an input data, for example, calculating the square root or logarithm, etc. Therefore, when performing signal processing on a fixed-point digital signal processor, how to efficiently and accurately Common functions like square root and logarithm are a pervasive problem. Usually, the common function value of the f...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F1/03
Inventor 邓昊冯宇红张晨
Owner VIMICRO CORP
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