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Improved Technique for Port Status Management

IP.com Disclosure Number: IPCOM000034545D
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-27

Publishing Venue

IBM

Related People

Authors:
Fasig, JL [+details]

Abstract

This technique improves performance of the AS400 Storage Subsystem by reducing the lines of code required to determine hardware port availability. AS400 HWC also managed these ports by declaring bit flags, which were reorganized into associative pairs as shown in Fig. 1. Note that the flag bit pairs are deliberately declared as the only elements of a named 16-bit field. This allows the microprocessor to make efficient memory accesses without forcing the compiler to generate extra code to mask off bits not related to this test. /***************** SA/DA Port Allocation Flags ******************/ /* */ /* This section contains the status of the DA DMA ports 0 and */ /* 1 and the other DA operations in general.