32位嵌入式系统中扩展精度数学算法实现

提出了一种32位嵌入式系统中应用的扩展精度数学算法。适用于缺乏数字协处理器硬件支持并且软件浮点运算达不到系统时间要求的系统。算法运算数据精度高、扩展性好。介绍了32位乘法、除法、开方算法以及64位加法、减法、乘法算法。     

基于VHDL的浮点算法研究

浮点运算是数字信号处理中最基本的运算,但因为现行EDA软件没有提供浮点运算功能,使其在FPGA中的实现却是个棘手问题.文中提出了一种基于VHDL的高精度浮点算法,并以9位实序列为例,通过浮点数表示、对阶操作、尾数运算以及规格化处理等步骤高效并准确地实现浮点加/减法、乘法、除法以及平方根等运算,最后在FPGA中下载并实现了上述浮点运算,并给出测试结果.测试数据表明:所设计的浮点算法在其浮点数位宽所对应的精度范围内,可以在FPGA上成功地实现包含加、减、乘、除及求平方根等各种浮点运算.     

80C196系列单片机高精度浮点运算及数制转换子程序

提供一组80C196单片机高精度浮点运算及数制转换子程序.阶码采用1字节移码,尾数采用双字节原码,精度为91/2位十进制数据.在16MHz时钟下,32位精度乘法及28位精度除法均不超过40μs,32位精度除法不超过80μs.程序有四舍五入功能及溢出判断功能.文中提供程序清单,可直接调用,为快速函数计算提供了有力支持.     

支持超越函数的浮点运算单元的设计与实现

介绍自主设计的龙腾C2微处理器中浮点运算单元的设计与实现.该处理器与Intel 80486DX4指令系统兼容,支持IEEE 754标准扩展精度的浮点基本函数和超越函数运算.介绍了浮点运算单元的结构,分析了实现超越函数的高精度CORDIC算法的流程,讨论了实现浮点超越函数运算的数据通路和控制通路结构,并给出了仿真结果和精度评估结果.仿真和分析的结果表明,浮点运算单元的设计满足龙腾C2微处理器的设计要求.     

基于编译原理的表达式计算器设计

通过对计算器功能的概述和算法的探讨,使用算符优先算法实现了表达式计算器.该表达式计算器能分析用户输入的表达式是否正确,支持括号运算、浮点运算、简单的四则运算、复杂的表达式运算、进制之间的相互转换等.该计算嚣操作简单,界面清晰.     

支持超越函数的浮点运算单元的设计与实现

介绍自主设计的龙腾C2微处理器中浮点运算单元的设计与实现。该处理器与Intel80486DX4指令系统兼容,支持IEEE754标准扩展精度的浮点基本函数和超越函数运算。介绍了浮点运算单元的结构,分析了实现超越函数的高精度CORDIC算法的流程,讨论了实现浮点超越函数运算的数据通路和控制通路结构,并给出了仿真结果和精度评估结果。仿真和分析的结果表明,浮点运算单元的设计满足龙腾C2微处理器的设计要求。     

80C196系列单片机高精度浮点运算及数制转换子程序

提供一组80C196单片机高精度浮点运算及数制转换子程序。阶码采用1字节移码，尾数采用双字节原码，精度为91／2位十进制数据。在16MHz时钟下，32位精度乘法及28位精度除法均不超过40цs，32位精度除法不超过80цs。程序有四舍五入功能及溢出判断功能。文中提供程序清单，可直接调用，为快速函数计算提供了有力支持。     

定点DSP C55X实现浮点相关运算

引言 DSP结构可以分为定点和浮点型两种.其中,定点型DSP可以实现整数、小数和特定的指数运算,它具有运算速度快、占用资源少、成本低等特点;灵活地使用定点型DSP进行浮点运算能够提高运算的效率.目前对定点DSP结构支持下的浮点需求也在不断增长,主要原因是: 实现算法的代码往往是采用C/C 编写,如果其中有标准型的浮点数据处理,又必须采用定点DSP器件,那么就需要将浮点算法转换成定点格式进行运算.同时,定点DSP结构下的浮点运算有很强的可行性,因为C语言和汇编语言分别具有可移植性强和运算效率高的特点,因此在定点DSP中结合C语言和汇编语言的混合编程技术将大大提高编程的灵活度,以及运算速度.     

多核浮点非线性运算协处理器的设计与实现

在载人航天飞船的终端仪器仪表设计中,处理算法中的浮点非线性运算常采用库函数实现,但软件实现非线性函数执行速度慢,限制了浮点算法的应用。为此,针对航天领域处理器不支持非线性函数运算的情况以及浮点算法执行速度慢的问题,提出一种多核并行执行浮点非线性运算处理方法,利用现场可编程门阵列内部并行架构带来的低延迟特性来提高非线性浮点运算的速度。仿真实验结果表明,该方法可计算有限定义域范围内的浮点非线性函数,有效提高浮点运算的执行速度。     

HDS-801系统中央处理机的可靠性设计

HDS-801系统是一台采用 74S系列中规模集成电路作为逻辑元件、半导体MOS大规模集成电路作为主存贮器的高性能中型通用电子计算机系统. 它的主要性能: ·32位字长; ·四种指令形式,共有190条指令; ·多通用累加器的运算处理结构; ·具有位运算操作,字节运算操作,定点运算操作浮点运算操作和双字长浮点运算操作;     

Rounding errors in random number generators

The deviations of the cumulative distribution function from the uniform one for the pseudorandom floating point values produced by integer arithmetics are discussed. It is shown that the converion from fixed point values into floating point values introduces specific artefacts even when the integer arithmetics guarantees ideal uniformity. Two type of defects are considered: the appearance of the value 1.0 among pseudorandom values, and the sharp jumps of uniformity at the level of discreteness which corresponds to the computer representation of the floating point values. The non-uniformity at small level of discreteness can be neglected in most cases, but the appearance of the parasitic value 1.0 where nobody expects it can be very dangerous if special precautions are not taken by the user. Both defects are demonstrated using the random number generator from the system library of the Microsoft Power Station Fortran 1.0.     

基于Goldschmidt算法的高性能双精度浮点除法器设计

针对双精度浮点除法通常运算过程复杂、延时较大这一问题,提出一种基于Goldschmidt算法设计支持IEEE-754标准的高性能双精度浮点除法器方法。首先,分析Goldschmidt算法运算除法的过程以及迭代运算产生的误差;然后,提出了控制误差的方法;其次,采用了较节约面积的双查找表法确定迭代初值,迭代单元采用并行乘法器结构以提高迭代速度;最后,合理划分流水站,控制迭代过程使浮点除法可以流水执行,从而进一步提高除法器运算速率。实验结果表明,在40 nm工艺下,双精度浮点除法器采用14位迭代初值流水结构,其综合cell面积为84902.2618 μm²,运行频率可达2.2 GHz;相比采用8位迭代初值流水结构运算速度提高了32.73%,面积增加了5.05%;计算一条双精度浮点除法的延迟为12个时钟周期,流水执行时,单条除法平均延迟为3个时钟周期,与其他处理器中基于SRT算法实现的双精度浮点除法器相比,数据吞吐率提高了3~7倍;与其他处理器中基于Goldschmidt算法实现的双精度浮点除法器相比,数据吞吐率提高了2~3倍。     

An algorithm to solve integer linear systems exactly using numerical methods

In this paper, we present a new algorithm for the exact solutions of linear systems with integer coefficients using numerical methods. It terminates with the correct answer in well-conditioned cases or quickly aborts in ill-conditioned cases. Success of this algorithm on a linear equation requires that the linear system must be sufficiently well-conditioned for the numeric linear algebra method being used to compute a solution with sufficient accuracy. Our method is to find an initial approximate solution by using a numerical method, then amplify the approximate solution by a scalar, and adjust the amplified solution and corresponding residual to integers so that they can be computed without large integer arithmetic involved and can be stored exactly. Then we repeat these steps to refine the solution until sufficient accuracy is achieved, and finally reconstruct the rational solution. Our approximating, amplifying, and adjusting idea enables us to compute the solutions without involving high precision software floating point operations in the whole procedure or large integer arithmetic except at the final rational reconstruction step. We will expose the theoretical cost and show some experimental results.     

Computing the Isolated Roots by Matrix Methods

Two main approaches are used, nowadays, to compute the roots of a zero-dimensional polynomial system. The first one involves Gröbner basis computation, and applies to any zero-dimensional system. But, it is performed withexact arithmetic and, usually, large numbers appear during the computation. The other approach is based on resultant formulations and can be performed with floating point arithmetic. However, it applies only to generic situations, leading to singular problems in several systems coming from robotics and computational vision, for instance.In this paper, reinvestigating the resultant approach from the linear algebra point of view, we handle the problem of genericity and present a new algorithm for computing the isolated roots of an algebraic variety, not necessarily of dimension zero. We analyse two types of resultant formulations, transform them into eigenvector problems, and describe special linear algebra operations on the matrix pencils in order to reduce the root computation to a non-singular eigenvector problem. This new algorithm, based on pencil decompositions, has a good complexity even in the non-generic situations and can be executed with floating point arithmetic.     

Computation of signal output probability for Boolean functions represented by OBDD

In [l] and [2], two algorithms have been proposed to calculate the output probability of Boolean functions represented by OBDDs, assuming that the input variables are equiprobable and each variable is statistically independent from others. In this paper, we point out that under these assumptions, the output probability calculation is equivalent to counting the number of minterms of the corresponding Boolean functions. An algorithm is proposed to compute the output probability using simple integer arithmetic as opposed to floating point arithmetic involved in [1,2]. To compute output probability of Boolean functions represented by shared OBDI)s and OBDDs with edge negation, we further propose a generalized algorithm.     

基于GIS技术的矿井供电设计与计算系统

本文介绍了基于GIS技术的矿井供电设计与计算系统主要模块的设计和实现。系统利用UML建模,GIS空间数据结构,使用VC开发,ACCESS数据库。把CAD与矿井供电结合,增加了电网参数计算功能,使本系统较好的解决传统的手工绘制供电图纸与计算问题。     

岸潜综合业务宽带通信关键技术与实现

在叙述对潜通信技术发展的基础上,根据岸潜宽带业务通信的需求,分析了浮筏平台、拖曳电缆和与潜艇匹配自动释放等系统的关键技术,给出了涉及岸潜无线通信信道的幅度衰落、时间色散和频率色散等衰落特性的分析以及岸潜无线通信要考虑的浮筏天线设计、岸站天线设计、分集和电平储备等主要因素。     

On Floating‐Point Normal Vectors

In this paper we analyze normal vector representations. We derive the error of the most widely used representation, namely 3D floating‐point normal vectors. Based on this analysis, we show that, in theory, the discretization error inherent to single precision floating‐point normals can be achieved by 2^50.2 uniformly distributed normals, addressable by 51 bits. We review common sphere parameterizations and show that octahedron normal vectors perform best: they are fast and stable to compute, have a controllable error, and require only 1 bit more than the theoretical optimal discretization with the same error.     

SQL Server数据库的应用级持续数据保护系统

针对传统数据容灾系统备份窗口大、容灾等级低等问题,提出并设计了与SQL Server数据库相结合的应用级持续数据保护容灾系统.系统通过SQL Server提供的应用程序接口API,读取数据库事务日志变化,从而实时捕获数据库数据变化,将捕获的数据变化以日志的形式缓存并传送到异地进行操作重放,实现异地远程容灾.当发生灾难时利用心跳检测、IP浮动等技术进行远程异地接管;当发生误操作时可根据日志文件恢复到之前的任意时间点,有效应对人为或意外造成的数据丢失和损坏     

一种改进的混合范围划分方法

混合范围划分方法给出了计算数据分置节点数的公式以及数据划分的方法;加强的混合范围划分方法通过引入可变范围的数据分块,达到了节点间数据存储量的一致,解决了混合范围划分方法的数据倾斜问题。为了达到系统运行时节点间的查询负载平衡,本文对上述方法进行了改进,引入了热度的概念来反映查询负载,通过对系统初始阶段的数
数据划分方法和系统运行阶段的数据迁移方法的改进,来达到上述目的。