Digital Equipment Corporation

Daniel L Murphy

Robert E Stewart

William B Noyce

Alan Kotok

A jacketing system automatically interfaces dissimilar program units during program execution on a computer system. Means are provided for detecting a call for execution of a second program unit having a second call standard form a first program unit having a first call standard during execution of the first program unit on the computer system. A procedure descriptor is used in the code for the first program unit and it includes a signature that defines the call standard for each incoming call to the first program unit. A bound procedure descriptor is also used in the code for each outgoing call from the first program unit and it includes a signature that defines the call standard for the target program unit. Jacketing routines are driven by the descriptors in jacketing calls between the two program units.

System and method for automatically interfacing call conventions between

An improved method for linking images at program activation is provided by use of a symbol vector in a sharable code image. The symbol vector is automatically constructed which the linker and operating system use to effect fast lookup of symbol values at program activation, thus providing flexibility similar to that of link-time binding. For each sharable image being constructed, the programmer provides a list of symbols which are to be made visible outside of the image. These symbols may be procedure names, data cells, absolute values, or any other valid use of a symbolic value. The order of this list must remain fixed from one image build to the next. From this list, the 'symbol vector' is constructed (as by the linker) of the value of each of the identified symbols, and the symbol vector is associated with the sharable image. A symbol table is also associated with the sharable image, where each symbol has the value of its index in the symbol vector. When resolving references to other images, the linker does a symbolic lookup in the symbol table of the target image and obtains the index into the target symbol vector. That index is bound into the calling image. Then, at program activation, the image activator uses the index bound into a calling image to obtain the current value of the symbol in the target image.

System for linking program units by binding symbol vector index in the

A central processor for use in a data processing system that is adapted for addressing a substantially larger virtual memory than the address space defined by the memory address field in an instruction normally provides. Information identifying an extended address is placed in working registers of the central processor. Other working registers in the central processor receive information corresponding to the memory word addressed by the instruction word. If the memory word requires indexing, the central processor adds the contents of an index register to the address contained in the memory address field of the memory word. If the resultant address is extended, the arithmetic and logic unit's carry logic is not inhibited and the larger address space is provided to one of the working registers. Concurrently, control logic is set within the central processor which causes the central processor to interpret the information as an extended address. If the memory word indicates that another memory word is required, the central processor performs similar calculations on the indirect word until an effective address is calculated. Several levels of indirection can be performed depending upon the characteristics of each preceding indirect word.

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Hollis, NH, United States of America

Daniel L Murphy