软件管道化方法

用完全数据关联图CDG来表述软件管道化问题,图中有向边表示循环中各指令间的关联性,同时提出了基础集的概念,平行可扩展的基础集可以覆循环的指令,文中用遗传算法来搜索基础集的最优解或次最优解,这种方法可以处理所有可能的数据关联性,从而可以将循环高度并行化。     

LS SIMD计算机的并行技术

文章主要讨论了LSSIMD计算机中所采用的并行技术数据并行技术、三级指令流水线并行技术与三组指令并行执行技术。     

Combining Coarse-Grained Software Pipelining with DVS for Scheduling Real-Time Periodic Dependent Tasks on Multi-Core Embedded Systems

In this paper, we combine coarse-grained software pipelining with DVS (Dynamic Voltage/Frequency Scaling) for optimizing energy consumption of stream-based multimedia applications on multi-core embedded systems. By exploiting the potential of multi-core architecture and the characteristic of streaming applications, we propose a two-phase approach to solve the energy minimization problem for periodic dependent tasks on multi-core processors with discrete voltage levels. With our approach, in the first phase, we propose a coarse-grained task-level software pipelining algorithm called RDAG to transform the periodic dependent tasks into a set of independent tasks based on the retiming technique (Leiserson and Saxe, Algorithmica 6:5–35, 1991). In the second phase, we propose two DVS scheduling algorithms for energy minimization. For single-core processors, we propose a pseudo-polynomial algorithm based on dynamic programming that can achieve optimal solution. For multi-core processors, we propose a novel scheduling algorithm called SpringS which works like a spring and can effectively reduce energy consumption by iteratively adjusting task scheduling and voltage selection. We conduct experiments with a set of benchmarks from E3S (Dick 2008) and TGFF () based on the power model of the AMD Mobile Athlon4 DVS processor. The experimental results show that our technique can achieve 12.7% energy saving compared with the algorithms in Zhang et al. (2002) on average.

一个流水线型三维DCT硬件核的设计

在优化3D-DCT算法的基础上,采用流水线型结构,系数转换、矩阵转置、数据装载和截位的通盘解决方式,构造一个流水线型的三维DCT硬件核,使运动图像的压解中DCT运算的CPU耗时下降十几倍,实现实时压缩。     

An Effective Software Pipelining Algorithm for Clustered Embedded VLIW Processors

This paper proposes a software pipelining framework, CALiBeR (ClusterAware Load Balancing Retiming Algorithm), suitable for compilers targetingclustered embedded VLIW processors. CALiBeR can be used by embedded systemdesigners to explore different code optimization alternatives, that is, high-qualitycustomized retiming solutions for desired throughput and program memory sizerequirements, while minimizing register pressure. An extensive set of experimentalresults is presented, demonstrating that our algorithm compares favorablywith one of the best state-of-the-art algorithms, achieving up to 50% improvementin performance and up to 47% improvement in register requirements. In orderto empirically assess the effectiveness of clustering for high ILP applications,additional experiments are presented contrasting the performance achievedby software pipelined kernels executing on clustered and on centralized machines.     

基于FPGA的32位浮点加法器的设计

在综合分析各种浮点加法器算法的基础上,提出了一种符合TI格式标准的32位浮点加法器,同时兼顾了速度和面积两方面因素.本设计在virtex-4系列FPGA上进行了实现,最高速度可达到182.415MHz,资源占用也较为合理.     

FPGA Implementation of Integer Transform and Quantizer for H.264 Encoder

This paper deals with the process of Transformation and Quantization that is carried out on each inter-predicted residual block in a video encoding process and their reduced complexity hardware implementation. H.264/AVC utilizes 4 × 4 integer transform, which is derived from the 4 × 4 DCT. We propose, a reduced complexity algorithm and a pipelined structure for the Core forward integer transform module. A multiplier-less architecture is realized with less number of shifts and adds compared to existing works. The corresponding inverse transform is exactly reversible. Each of the transformed coefficients is quantized by a scalar quantizer. The quantization step size can be varied from macroblock to macroblock. The proposed unified pipelined architecture outperforms many recent implementations in terms of gate count and is capable of processing a 4 × 4 residual block in 4 clock cycles.

TMS320C6X的SPLOOP技术

软件流水是一种实现循环迭代中指令级并行的指令调度技术。它可以克服多周期指令延迟对CPU处理性能的影响,保证循环核的运行效率最优。从C64X+开始,TMS320C6X系列DSP引入SPLOOP技术,软件上增加SPLOOP(D/W)、SPKERNEL等相关指令,硬件上增加软件流水缓存等专用模块,通过模调度软件流水模式,有效缩小了软件代码量,提升了执行代码效率。一般情况下,采用SPLOOP技术后机器编译输出的循环代码质量很高,编程人员无需再对代码进行进一步的手工优化。     

基于M/2点FFT的MLT快速算法及其FPGA实现

传统的基于DSP(数字信号处理器)实现的MLT(调制重叠变换)由于DSP的特点在速度上已经不能满足实际系统的要求,而随着FPGA(现场可编程门阵列)技术的发展,使得基于FPGA的MLT高速处理成为可能。基于FPGA的特点,选用了M/2点FFT(快速傅里叶变换)实现MLT快速算法,并对其进行了修正,采用并行处理和流水线技术,完成了此快速算法的FPGA硬件设计。仿真结果表明,设计满足了信号实时处理的要求,大大提高了信号的处理速度。     

基于汇编语言的DSP源代码优化技术的研究

介绍了一种利用汇编语言 ,借助流水线技术优化 TMS3 2 0 C60 0 0源代码的方法。该方法能够提高代码的执行效率 ,为实际工程中复杂算法的实时性提供了软件保障。以图像的测量跟踪程序为例 ,介绍了使用汇编语言 ,利用流水线结构优化源代码的方法和步骤 ,在实验中得出三个程序优化前和优化后的执行时间情况对比。窗口尺寸为 1 0 0× 80的重心跟踪程序优化前所用时间为 1 640μs,优化后所用时间为 48μs,执行时间缩短了 3 4.2倍 ,充分验证了汇编语言和流水线技术对 TMS3 2 0 C60 0 0源代码的优化效果 ,为实时条件下应用更为复杂和有效的算法开辟了广阔的空间