基于TCAM报文分类的范围编码方案

针对现有范围编码方案三态内容寻址存储器(TCAM)利用率不高及更新性能差问题,提出一种混合范围编码方案(Hybrid-RES),根据扩展系数和出现频率,采用纵向或横向扩展编码策略对范围字段进行编码。纵向扩展编码策略利用格雷码的对称映射特征设计一种格雷范围编码算法,对纵向扩展出TCAM表项数目较多的范围字段采用横向扩展编码策略。理论分析和实验结果表明,Hybrid-RES可以较大地提高TCAM利用率,同时获得较好的更新性能。     

面向多核的基于RSTM系统的冲突管理策略

程序并行化是充分发挥多核处理器性能的有效手段。现有编程模型受锁、管道等同步方式的约束,并行度很难提高。针对上述问题,提出一种面向多核的基于Rochester软件事务存储(RSTM)系统的冲突管理策略,在现有编程语言中提供接口,通过事务方式提高程序并行度,以优先级方式解决2个事务发生冲突时的裁决问题,减少不必要的一致性验证,减小系统开销。     

基于三态内容可寻址器件的P2P流量控制

介绍一种基于三态内容可寻址器件及TCP速率的控制机制,研究吉比特链路的P2P流量检测与控制方法,提出一个PM模型,采用高精度的特征码匹配方法以识别P2P数据包,依概率对P2P数据包进行随机丢弃,从而达到控制高带宽P2P流量的目的。仿真实验结果表明,该模型可根据丢弃概率有效地控制P2P流量,改善非P2P应用的服务质量。     

MIPS内存管理单元的设计与实现

设计MIPS32 4kc处理器内存管理单元(MMU),该模块对处理器地址进行合法性检查,并按照不同的地址空间对虚拟地址进行静态或动态映射。在硬件上采用三级流水线方式实现JTLB,并为处理器指令端口和数据端口设计相应的快表以提高TLB的查询速度。MMU与总线接口模块的时序采用简化的AMBA协议,与处理器进行联合调试并运行Linux操作系统,同时在功能上通过FPGA验证。该模块经过DC综合后,面积约为32K等效逻辑门。     

MP3音频解码在内存空间中的优化

MP3采用MPEG-1 LayerⅢ音频压缩编码标准,数据压缩率高、失真小,同时解码需要占用较大的内存空间。针对以上问题,在16 bit定点数字信号处理器芯片实现MP3解码算法时,对一些复杂算法进行优化,并且通过合理分配内部动态和静态存储空间,对动态存储器进行直接存储器存取操作,将动态数据临时存储在外存中,对静态存储器通过空间混用和压缩冗余数据等方法缩减内存占用空间。在解码速度提高的情况下,内存占用从大于40 KB降至15.9 KB。     

高速SDRAM控制器的嵌入式设计

为适应高数据吞吐速率的应用场合,在分析同步动态随机存储器(SDRAM)控制器工作原理的基础上,研究支持高数据处理效率可连续读写操作的存储控制算法。利用现场可编程门阵列设计SDRAM嵌入式存储控制器,采用CMD命令形式,根据猝发长度分配连续读写延时,通过数据通道控制与读写操作协同工作提高数据处理效率。测试结果表明,该控制器运行频率高于100 MHz,数据处理效率大于95%,适用于视频采集数据缓存及大型LED显示控制中。     

Light-weight salient foreground detection for embedded smart cameras

An embedded smart camera is a stand-alone unit that not only captures images, but also includes a processor, memory and communication interface. Battery-powered, embedded smart cameras introduce many additional challenges since they have very limited resources, such as energy, processing power and memory. Computer vision algorithms running on these camera boards should be light-weight and efficient. Considering the memory requirements of an algorithm and its portability to an embedded processor should be an integral part of the algorithm design in addition to the accuracy requirements. This paper presents a light-weight and efficient background modeling and foreground detection algorithm that is highly robust against lighting variations and non-static backgrounds including scenes with swaying trees, water fountains and rain. Compared to many traditional methods, the memory requirement for the data saved for each pixel is very small in the proposed algorithm. Moreover, the number of memory accesses and instructions are adaptive, and are decreased depending on the amount of activity in the scene. Each pixel is treated differently based on its history, and instead of requiring the same number of memory accesses and instructions for every pixel, we require less instructions for stable background pixels. The plot of the number of unstable pixels at each frame also serves as a tool to find the video portions with high activity. The proposed method selectively updates the background model with an automatically adaptive rate, thus can adapt to rapid changes. As opposed to traditional methods, pixels are not always treated individually, and information about neighbors is incorporated into decision making. The results obtained with nine challenging outdoor and indoor sequences are presented, and compared with the results of different state-of-the-art background subtraction methods. The ROC curves and memory comparison of different background subtraction methods are also provided. The experimental results demonstrate the success of the proposed light-weight salient foreground detection method.     

提取与检验电子证据的若干实践要点

提取电子证据应当按照案发后及时保护好计算机犯罪现场、保存涉案计算机和各种资料、收集相关资料、询问当事人、现场勘查文档记录等步骤开展工作。电子证据的存储介质不同,对其检验与固定的方法也不尽相同。     

嵌入式Linux下的FRAM驱动程序设计

针对铁电存储器(FRAM)在基于ARM9的嵌入式Linux系统下设备节点的读写及应用问题,研究Linux系统的驱动设计,分析FRAM的工作原理和硬件特性,提出基于Linux系统标准驱动架构与铁电底层预处理、读写、控制等工作机制相结合的FRAM驱动程序设计与实现流程。底层实现采用内核级基于FRAM的寻址方式,结果证明了该驱动在相应数据存储、传输中的可行性与稳定性。     

基于CK-CPU的Linux2.6实时性能优化

针对Linux2.6在实时中断应用上的局限性,提出一种基于CK-CPU的实时性能优化方案。设计用于实时中断的快速中断请求(FIQ)机制,在FIQ处理程序退出时增加实时进程调度策略,将FIQ服务程序的公共代码和堆栈保留在便笺式存储器中,减少FIQ服务程序的内存访问次数并加快其执行速度。实验结果证明,该方案可显著提高Linux2.6的实时性能。