利用MIPS® DSP ASE进行高效DSP编程与优化指南

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本篇文档"Effective DSP Programming using MIPS® DSP Application Specific Extensions"（MD00475，修订版1.22，发布日期2008年6月30日）是一篇关于如何有效利用MIPS® DSP Application Specific Extensions (DSP ASE) 进行数字信号处理编程的专业指南。文档主要涵盖以下几个关键知识点： 1. **MIPS DSP ASE简介**：文档首先解释了MIPS 32(R) DSP ASE，这是一种针对特定应用设计的扩展，旨在提升数字信号处理器（DSP）的性能。它提供了专门针对DSP任务设计的指令集，如滤波、傅里叶变换等。 2. **编程基础**：文章从基础概念出发，定义了基本的数字信号处理术语，比如信号的定义和典型目标。此外，还介绍了DSP处理系统通常追求的目标，以及常见的DSP操作，如加法、减法、乘法和除法等。 3. **新指令集介绍**：通过分类和具体示例，文档深入剖析了DSP ASE的新指令，这些指令针对信号处理任务进行了优化，如快速傅里叶变换（FFT）、滤波器设计等。同时，文中强调了指令执行时间的重要性，以确保实现最佳性能。 4. **代码转换与实例**：作者通过一系列实例展示了从C语言代码到MIPS 32汇编语言再到最终的DSP ASE实现的过程，让读者理解如何逐步优化代码以利用这些特殊扩展。 5. **性能优化指南**：文档的结尾部分提供了一些实用的代码优化策略，帮助开发者更好地利用DSP ASE进行高效的编程，以提升程序运行速度和降低功耗。这篇文档为MIPS DSP ASE的使用者提供了丰富的资源，包括理论知识、实践技巧和优化建议，旨在帮助他们在实际项目中提高 DSP 应用程序的性能和效率。对于那些从事或希望了解MIPS DSP编程的工程师来说，这是一份非常有价值的参考资料。

2 Introduction to Digital Signal Processing

6 Effective DSP Programming using MIPS® DSP Application Specific Extensions, Revision 01.22

output[k] = s;

}

In this code example, N is the total number of samples that are processed and T is the number of ﬁlter coefﬁcients

(taps). The coefﬁcients are stored in the array called ﬁlter in reverse order to simplify the array indexing. The inner-

most loop computes the dot product of the ﬁlter coefﬁcients and the group of T input samples starting from sample k.

Note the MAC operation at the heart of the code - one input sample is multiplied by one coefﬁcient and the product is

accumulated. Since MAC operations are very common in DSP algorithms, processors targeting DSP applications

often provide specialized MAC instructions. The MIPS32 instruction set provides MAC instructions, while its capa-

bilities are enhanced by the DSP ASE.

2.4 DSP Data Types

The example in the previous section does not make the data types explicit. It is easiest to perform all calculations

using ﬂoating-point numbers, but hardware ﬂoating-point support is not always available. Even if it is, the perfor-

mance of ﬂoating-point operations might be lower than that of integer operations and processors supporting ﬂoating-

point units are typically bigger and have a higher cost. To avoid magnitude growth of the multiplication product, DSP

algorithms often represent the data samples and the coefﬁcients used in the computation as fractional numbers

between -1 and +1. This is accomplished by placing the binary point separating the integer and fractional parts of the

number immediately after the sign bit. Some of the commonly used ﬁxed-point (or fractional) formats include Q15

(sign bit, zero integer bits, 15 fractional bits) and Q31 (sign bit, zero integer bits, 31 fractional bits). Sometimes data

formats with one or more integer bits are used, trading off increased dynamic range for lower precision.

Note that the same hardware that performs integer add, subtract, and multiply operations can also be used for ﬁxed-

point operations. However, a fractional multiplication operation needs to be shifted left by one bit to re-align the data

to a correct fractional double-width product. This is because multiplying two numbers in ﬁxed-point format produces

one redundant sign bit. The fractional multiply instructions in the MIPS32 DSP ASE automatically perform this cor-

rection.

2.5 Saturation And Rounding

Saturation and rounding are rare operations in non-DSP code, but used often in DSP algorithms. Saturation limits the

result of a computation to the range implied by the input data type, thus avoiding overﬂow and underﬂow conditions.

For example, an image processing application will typically use 8-bit unsigned integers for pixel representation, with

the value of zero corresponding to black and the value of 255 corresponding to white.

Now imagine that we have to make an image 25% brighter. If we have a somewhat white pixel with a value of 220

and we multiply it by 1.25 to make it 25% brighter, we would get:

220 x 1.25 = 275

But 275 is not representable as an 8-bit number! Instead, the multiplication result will wrap-around to

275 - 256 = 19,

and suddenly we have a somewhat dark pixel! Saturation prevents cases like this by clipping the result to the maxi-

mum allowed value-- in this example, 255:

saturate(275) = 255

The rounding operation is used when the precision of some calculated result needs to be reduced. For example, multi-

plying Q15 numbers produces a Q31 result, but if we want to store it to memory as a 16-bit value, then we simply

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利用MIPS® DSP ASE进行高效DSP编程与优化指南

dsp编程优化

DSP编程技巧（很有用）

DSP程序优化方法

XT N安帧处理的应用，帧长10ms,预计需要处理100万条指令，那么选择处理能力为多少的DSP最为经济(处理能力和价K&rETEL aБхIЕLЬ) ( )

将c语言转化为mips指令

写出以下缩写词的中英文全称：DSP、MMACS、MIPS、MOPS、 MFLOPS。

dsp28305 中文资料

reworks操作系统 dsp

计算机体系结构a 为 10mips, b 为 20mips, c 为 40mips。 三台机器实际性能相同。

MIPS TAM设计的预备知识

最新资源

计算机体系结构a 为 10mips, b 为 20mips, c 为 40mips。三台机器实际性能相同。