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Creating Dummy Control Sections Additive for Addressing

IP.com Disclosure Number: IPCOM000086511D
Original Publication Date: 1976-Sep-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

DeOrsey, LS: AUTHOR [+3]

Abstract

In programming systems, it is often the case that a data structure used by an assembly language program is a composite of other data structures or control blocks, where each control block is defined or `mapped' by its own individual dummy control section (DSECT), thus requiring its own base register for addressing. Often, these mappings, used for symbolic referencing of the fields within the data structure, are generated by macroinstructions or COPY statements, so that the programmer designing a program has no control over the contents of these DSECTs.

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Creating Dummy Control Sections Additive for Addressing

In programming systems, it is often the case that a data structure used by an assembly language program is a composite of other data structures or control blocks, where each control block is defined or `mapped' by its own individual dummy control section (DSECT), thus requiring its own base register for addressing. Often, these mappings, used for symbolic referencing of the fields within the data structure, are generated by macroinstructions or COPY statements, so that the programmer designing a program has no control over the contents of these DSECTs.

These dummy control sections can be combined so that they may all be addressed with a single base register, resulting in a savings in the usage of machine registers, a limited resource. This permits programs to be optimized to a greater degree since more registers will be available and fewer instructions will be spent loading them to establish addressability to individual control blocks.

To combine dummy sections of constant (i.e., nonvariable) size, use is made of a function available through many assemblers. This function, known as `OPSYN' in the case of many IBM assemblers, permits any assembler operation code or pseudo-operation code to be assigned new attributes, as well as to define new codes which have the same attributes as existing codes. By defining a new code with the same attributes as `DSECT', then redefining `DSECT' to have another set of attributes, the `DSECT' statements appearing...