公开(公告)号：WO1992015943A1

公开(公告)日：1992-09-17

申请号：PCT/US1992001284

申请日：1992-02-18

Applicant: DIGITAL EQUIPMENT CORPORATION

Inventor： DIGITAL EQUIPMENT CORPORATION ,  BLICKSTEIN, David, Scott ,  DAVIDSON, Caroline, Sweeney ,  FAIMAN, Robert, Neil, Jr. ,  GROVE, Richard, Barry ,  HOBBS, Steven, O. ,  MURPHY, Dennis, Joseph

IPC: G06F09/45

CPC classification number: G06F8/433 ,  G06F8/437 ,  G06F8/443 ,  G06F8/447

Abstract: A compiler framework uses a generic "shell" or control and sequencing mechanism, and a generic back end (where the code generator is target-specific). The generic back end includes the functions of optimization, register and memory allocation, and code generation. The shell may be executed on various host computers, and the code generation function of the back end may be targeted for any of a number of computer architectures. A front end is tailored for each different source language, such as Cobol, Fortran, Pascal, C, C++, Ada, etc. The front end scans and parses the source code modules, and generates from them an intermediate language ("IL") representation of the programs expressed in the source code. This IL is constructed to represent any of the source code languages in a universal manner, so the interface between the front end and back end is of a standard format, and need not be rewritten for each language-specific front end. The IL representation generated by the front end is based upon a tuple as the elemental unit, where each tuple represents a single operation to be performed, such as a load, a store, an add, a label, a branch, etc. A data structure is created by the front end for each tuple, with fields for various necessary information. One feature of the invention is a mechanism for representing effects and dependencies in the interface between front end and back end; a tuple has an effect if it writes to memory, and has a dependency if it reads from a location which some other node may write to. A mechanism independent of source language is provided for describing the effects of program execution. Another feature is the use in the optimization part of the compiler of a method for analyzing induction variables, where the improvement is to use the side effects sets used to construct IDEF sets. Another feature is a mechanism for "folding constants" (referred to as K-folding or a KFOLD routine), included as one of the optimizations. A further feature is the type definition mechanism, referred to as the TD module, which provides mechanisms used by the front end and the compiler of the back end in constructing program type information to be incorporated in an object module for use by a linker or debugger. Another feature is a method for doing code generation using code templates in a multipass manner.

Abstract translation: 编译器框架使用通用的“shell”或控制和排序机制，以及通用后端（代码生成器是特定于目标的）。 通用后端包括优化，寄存器和内存分配以及代码生成的功能。 外壳可以在各种主机上执行，并且后端的代码生成功能可以针对多种计算机体系结构中的任意一种。 前端针对每种不同的源语言进行定制，如Cobol，Fortran，Pascal，C，C ++，Ada等。前端扫描和解析源代码模块，并从中生成中间语言（“IL”） 在源代码中表示的程序的表示。 该IL被构造为以通用方式表示任何源代码语言，因此前端和后端之间的接口是标准格式，并且不需要为每个特定于语言的前端重写。 由前端生成的IL表示基于元组作为元素单元，其中每个元组表示要执行的单个操作，例如加载，存储，添加，标签，分支等。数据 结构由每个元组的前端创建，具有各种必要信息的字段。 本发明的一个特征是用于表示在前端和后端之间的接口中的效果和依赖性的机制; 如果一个元组写入内存，则该元组有效果，如果从其他节点可能写入的位置读取该元组，则具有依赖关系。 提供独立于源语言的机制来描述程序执行的效果。 另一个特征是在编译器的优化部分中使用一种分析感应变量的方法，其中改进是使用用于构建IDEF集合的副作用集。 另一个特征是包括作为优​​化之一的“折叠常数”（称为K折叠或KFOLD例程）的机制。 另一个特征是类型定义机制，称为TD模块，其提供前端使用的机制和后端的编译器来构造要并入到对象模块中以供由链接器或调试器使用的程序类型信息 。 另一个特征是使用多重方式的代码模板进行代码生成的方法。

公开(公告)号：WO1992015938A1

公开(公告)日：1992-09-17

申请号：PCT/US1992001776

申请日：1992-03-03

Applicant: DIGITAL EQUIPMENT CORPORATION

Inventor： DIGITAL EQUIPMENT CORPORATION ,  SITES, Richard, L.

IPC: G06F09/44

CPC classification number: G06F8/52

Abstract: Possible values for a computed destination address of an execution transfer instruction are found by a backward search through a flowgraph of a program. During the search, a symbolic expression for the destination address is successively modified to reflect the effect of each prior instruction until the symbolic expression represents an absolute or program-counter relative address, or until the search can no longer continue. The search can no longer continue, for example, when an instruction is reached that affects the value of the expression in an indefinite way. When backward symbolic execution reaches the entry point of a block in the flowgraph, backward symbolic execution proceeds backward to each predecessor block that has not already been examined for the execution transfer instruction. Therefore multiple definite values as well as a value of "unknown" may be found for a computed destination address. Preferably backward symbolic execution is performed while constructing the flowgraph, in order to find the locations of additional instructions. As additional instructions are found, new blocks and new paths between blocks are added to the flowgraph. Backward symbolic execution is repeated when the new paths may provide additional values for the computed destination addresses.

Abstract translation: 执行传输指令的计算目标地址的可能值是通过程序流程图的后向搜索找到的。 在搜索期间，连续修改目的地地址的符号表达式以反映每个先前指令的效果，直到符号表达式表示绝对或程序计数器的相对地址，或直到搜索不再继续。 搜索无法继续，例如，当达到一种无限期影响表达式值的指令时。 当向后符号执行到达流程图中的块的入口点时，向后的符号执行向后返回到尚未被检查用于执行传送指令的每个前导块。 因此，可以为计算的目的地地址找到多个确定值以及“未知”的值。 优选地，在构建流程图时执行向后符号执行，以便找到附加指令的位置。 随着附加说明的发现，块之间的新块和新路径被添加到流程图中。 当新路径可能为计算出的目的地地址提供附加值时，重复向后符号执行。

公开(公告)号：WO1992013413A1

公开(公告)日：1992-08-06

申请号：PCT/US1992000553

申请日：1992-01-24

Applicant: DIGITAL EQUIPMENT CORPORATION

Inventor： DIGITAL EQUIPMENT CORPORATION ,  PERLMAN, Radia, J. ,  HAWE, William, R. ,  BACKES, Floyd, J. ,  KONING, G., Paul ,  MITTON, David, J.

IPC: H04L12/46

CPC classification number: H04L12/1836 ,  H04L12/46 ,  H04L45/742 ,  H04L2212/00

Abstract: There is provided means to preserve the multicast address of a frame on a first communications system having a large multicast address space when the frame is forwarded onto a second communications system having a small multicast address space. A connection apparatus is provided for connecting a first communications system with a second communications system. There is a means for receiving at least one first frame from said first communications system, said at least one first frame having a destination address field, said destination address field containing a desired destination address, and there is a means for forwarding said at least one first frame onto said second communications system as a second frame, and for writing a second destination address into a destination address field of said second frame. Also there is a means for writing said desired destination address into a predetermined field of said second frame, and a means for writing an indicator into said second frame, said indicator capable of being interpreted by a receiving station to mean that said desired destination address is written into said predetermined field of said second frame. The frame may be forwarded onto a third communications system supporting the multicast address structure of the first communications system, and the multicast address is recovered from the representation of the multicast address written into the second frame and the multicast address is written into the address field of a third frame transmitted onto the third communications system.

Abstract translation: 提供了当帧被转发到具有小的多播地址空间的第二通信系统时，在具有大的多播地址空间的第一通信系统上保留帧的多播地址的装置。 提供一种用于将第一通信系统与第二通信系统连接的连接装置。 存在用于从所述第一通信系统接收至少一个第一帧的装置，所述至少一个第一帧具有目的地地址字段，所述目的地地址字段包含期望的目的地地址，并且存在用于转发所述至少一个 第一帧到第二通信系统作为第二帧，并且用于将第二目的地地址写入到所述第二帧的目的地地址字段中。 还有一种用于将所述期望的目的地地址写入所述第二帧的预定字段的装置，以及用于将指示符写入所述第二帧的装置，所述指示符能够被接收站解释为意味着所述所需目的地址是 写入所述第二帧的所述预定场。 帧可以转发到支持第一通信系统的多播地址结构的第三通信系统，并且多播地址从写入第二帧的多播地址的表示中恢复，多播地址被写入到 第三帧传输到第三通信系统。

公开(公告)号：WO1992013410A1

公开(公告)日：1992-08-06

申请号：PCT/US1992000586

申请日：1992-01-24

Applicant: DIGITAL EQUIPMENT CORPORATION

Inventor： DIGITAL EQUIPMENT CORPORATION ,  BACKLES, Floyd, J. ,  HAWE, William, R. ,  KONING, G., Paul ,  MITTON, David, J. ,  PERLMAN, Radia, J.

IPC: H04L12/18

CPC classification number: H04L12/1836 ,  H04L12/46 ,  H04L45/742 ,  H04L2212/00

Abstract: There is provided a means to preserve the multicast address of a frame on a first communications system having a large multicast address space when the frame is forwarded onto a second communications system having a small multicast address space. The invention comprises a connection apparatus for connecting a first communications system with a second commmunications system and has a means for receiving at least one first frame from the first communications system, the at least one first frame having a multicast destination address, the multicast destination address requiring the at least one first frame to be transmitted onto the second communications system. Also there is a means for writting a representation of the multicast address into a second frame and for transmitting the second frame onto the second communications system.

Abstract translation: 当帧被转发到具有小的多播地址空间的第二通信系统时，提供了一种在具有大的多播地址空间的第一通信系统上保留帧的多播地址的装置。 本发明包括用于将第一通信系统与第二通信系统连接的连接装置，并且具有用于从第一通信系统接收至少一个第一帧的装置，所述至少一个第一帧具有组播目的地地址，多播目的地址 要求将至少一个第一帧传送到第二通信系统上。 还有一种用于将组播地址的表示写入第二帧并用于将第二帧发送到第二通信系统的装置。

公开(公告)号：WO1992013409A1

公开(公告)日：1992-08-06

申请号：PCT/US1992000585

申请日：1992-01-24

Applicant: DIGITAL EQUIPMENT CORPORATION

Inventor： DIGITAL EQUIPMENT CORPORATION ,  PERLMAN, Radia, J. ,  BACKES, Floyd, J. ,  HAWE, William, R. ,  KONING, G., Paul. ,  MITTON, David, J.

IPC: H04L12/18

CPC classification number: H04L12/1836 ,  H04L12/46 ,  H04L45/742 ,  H04L2212/00

Abstract: Use of a multicast address in a LAN, where the LAN does not support an adequate multicast address space, is implemented. An apparatus is provided for delivering a multicast address to a station on a local area network, where the local area network does not suppport the multicast address. There is a means for transmitting a frame on the local area network, the frame having; a predetermined field containing a reference to the multicast address, an indicator, the indicator capable of being interpreted by a receiving station to mean that the multicast address may be recovered from the frame by parsing the frame, and an applications program may be executed in response to the multicast address. Also, the apparatus may have a receiving station capable of receiving the frame; and there may be a means, in the receiving station, for executing an applications program in response to the multicast address.

Abstract translation: 在LAN中不支持足够的多播地址空间的LAN中使用组播地址。 提供了一种用于将组播地址传送到局域网上不支持组播地址的局域网上的站的装置。 存在用于在局域网上发送帧的装置，该帧具有： 包含对多播地址的引用的预定字段，指示符，能够由接收站解释的指示符，表示可以通过解析帧来从帧中恢复多播地址，并且可以响应地执行应用程序 到组播地址。 此外，该装置可以具有能够接收该帧的接收站; 并且在接收站中可以存在用于响应于多播地址执行应用程序的手段。

公开(公告)号：WO1992012587A1

公开(公告)日：1992-07-23

申请号：PCT/GB1992000034

申请日：1992-01-08

Applicant: DIGITAL EQUIPMENT CORPORATION ,  HARPER, John

Inventor： DIGITAL EQUIPMENT CORPORATION ,  PERLMAN, Radia, J. ,  HAWE, William

IPC: H04L12/46

CPC classification number: H04L45/28 ,  H04L12/4604 ,  H04L12/462 ,  H04L12/4633 ,  H04L45/00 ,  H04L45/18 ,  H04L45/48

Abstract: A technique for logically connecting local area networks (LANs) that may be separated by wide area networks containing routers and other network components. A logical link is formed between two bridge-like devices called tunnelers, such that, once a tunnel has been established between two LANs, other devices on the LANs can communicate as if the tunnel were a bridge. The tunneling mechanism of the invention requires that each LAN or extended LAN have only one active tunneler at any particular time, referred to as the designated tunneler, and each of the tunnelers is configured to have knowledge of the identities of the other tunnelers. A tunnel is established after a successful exchange of messages between two tunnelers, and then traffic may be forwarded through the tunnel in a transparent manner. The tunneling mechanism permits messages to be forwarded between LANs separated by a wide area network containing routers. Moreover, the mechanism permits filtering of traffic, such that only selected types of traffic, or messages for selected destinations or from selected sources, are forwarded through tunnels. The tunneling mechanism inherently precludes the formation of closed communication loops. An alternate embodiment of the invention optimizes the configuration process for particular network topologies.

Abstract translation: 一种用于逻辑连接可能由包含路由器和其他网络组件的广域网分隔的局域网（LAN）的技术。 在称为隧道传输器的两个类似桥的设备之间形成逻辑链路，使得一旦在两个LAN之间建立了隧道，则LAN上的其他设备可以像隧道是桥接一样进行通信。 本发明的隧道机制要求每个LAN或扩展LAN在任何特定时间仅具有一个主动隧道，称为指定的隧道，并且每个隧道被配置为具有其他隧道的身份知识。 在两个隧道之间成功交换消息之后建立隧道，然后可以透明地通过隧道转发流量。 隧道机制允许在由包含路由器的广域网分离的LAN之间转发消息。 此外，该机制允许对流量进行过滤，使得仅选择类型的流量或者所选目的地或来自所选源的消息通过隧道转发。 隧道机制固有地阻止了封闭通信环路的形成。 本发明的替代实施例优化了特定网络拓扑的配置过程。

公开(公告)号：WO1992005492A1

公开(公告)日：1992-04-02

申请号：PCT/US1991006947

申请日：1991-09-24

Applicant: DIGITAL EQUIPMENT CORPORATION

Inventor： DIGITAL EQUIPMENT CORPORATION ,  ROSICH, Mitchell, N.

IPC: G06F12/06

CPC classification number: G06F12/0676 ,  G06F12/0684

Abstract: In a data processing system, a memory board recognizes the presence of a special condition in the system, such as a 128 MB memory board. In such a situation, the memory board configures itself to map its address space accordingly, such as around a "hole" in the available memory to prevent conflicts between memory space and I/O space. In the absence of the special condition, the memory space will be contiguous. In addition, slot identification signals are passed sequentially to aid the memory boards in determining where their address spaces exist.

Abstract translation: 在数据处理系统中，存储器板识别系统中存在特殊状况，例如128MB存储器板。 在这种情况下，存储器板将其自身配置为相应地映射其地址空间，例如在可用存储器中的“孔”周围，以防止存储空间与I / O空间之间的冲突。 在没有特殊条件的情况下，内存空间将是连续的。 此外，时隙识别信号被顺序通过以帮助存储器确定它们的地址空间在何处存在。

公开(公告)号：WO1991007719A1

公开(公告)日：1991-05-30

申请号：PCT/US1990006591

申请日：1990-11-10

Applicant: DIGITAL EQUIPMENT CORPORATION

Inventor： DIGITAL EQUIPMENT CORPORATION ,  HARROW, Jeffrey, Rubin

IPC: G06F09/44

公开(公告)号：WO1991006088A2

公开(公告)日：1991-05-02

申请号：PCT/US1990005947

申请日：1990-10-16

Applicant: DIGITAL EQUIPMENT CORPORATION

Inventor： DIGITAL EQUIPMENT CORPORATION ,  FISHER, Edward, G. ,  GILBERT, Peter, D.

IPC: G09G01/00

CPC classification number: G09G5/30

Abstract: A method of encoding the characters of a character set, wherein the characters have a plurality of attributes (e.g., base, diacritical, and case), and wherein each attribute may have a plurality of values. The method comprises the steps of: dividing a multi-digit code into a plurality of parts, assigning each attribute to a different part, and, within each part, assigning a different numerical code to each different value of the attribute.

Abstract translation: 一个字符集的字符的编码的方法，其特征在于，所述字符具有多个属性（例如，碱，音调符号，和断裂），并且其中每个属性可以具有多个值。 该方法包括将多位数代码划分成多个部分的，分配每个属性到一个不同的部分的步骤，并且在每个部分，分配不同的数字代码的属性的每个不同的值。

公开(公告)号：WO1991003020A1

公开(公告)日：1991-03-07

申请号：PCT/DE1990000643

申请日：1990-08-23

Applicant: DIGITAL EQUIPMENT CORPORATION ,  SCHLAGE, Thomas

Inventor： DIGITAL EQUIPMENT CORPORATION

IPC: G06F13/28

CPC classification number: G06F13/28

Abstract: In a data processing system with a central processing unit (CPU), a main store (2) and a system bus (3), which may be connected to the main store (2) may be directly connected to the CPU (1) and there are a first switching unit (5) which controls the connection between the CPU (1) and the main store (2) and a second switching units (5, 7) are so interconnected that only one of them can release the existing connection of the CPU (1) or the system bus (3) to the main store. Here the main store, the first and second circuit and the first and second buffers are fitted on the same board as the CPU (1).

Abstract translation: 在具有中央处理单元（CPU）的数据处理系统中，可以连接到主存储器（2）的主存储（2）和系统总线（3）可以直接连接到CPU（1）和 存在控制CPU（1）和主存储（2）之间的连接的第一切换单元（5），并且第二交换单元（5,7）互连，使得只有其中一个可以释放现有的连接 CPU（1）或系统总线（3）连接到主存储。 这里，主存储器，第一和第二电路以及第一和第二缓冲器安装在与CPU（1）相同的板上。