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Article #298Re: assembly-language coding conventions (using patch areas)
From: David Cole
Date: Sun, 04 Sep 2005 16:28
Date: Sun, 04 Sep 2005 16:28
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3605 bytes
BBlack writes: > Another point: a pre-assembled patch area is usually > covered by an existing base register, while an EXTENDed > area may not be. JGilmore wrote: > and this is certainly true. It is not, however, very > interesting. Base registers retain their traditional > usefulness for addressing blocks of constants and, > sometimes, DSECTs. For almost all other purposes much > better constructs are now available and should be used > instead. BDissen wrote: > It is much better to use a pre-calculated base/displacement > than to [manually] calculate the relative offset and divide > by two (and is it relative to the current instruction > address, or the new PSW? Same for BRC and LARL? - I should > look it up). > > It is better to reduce the chance of error, rather than make > things fancy. Ben: The chance of error can be reduced *substantially* for large zaps (now matter what addressing method you prefer) if you'd use an ASM2ZAP program: a tool that scrapes a "PRINT ON,GEN,DATA" listing and produces zap statements based on the extracted machine code. Howard Gilbert of Yale's computer center wrote one decades ago. I think it might be available on the CBT modes tape. It's also available for free download from my web site at "www.colesoft.com/utilities.html". Developing a methodology for using ASM2ZAP is not that hard. Just design an assembly that represents your intended zap and use appropriate DSECT, ORG, and USING statements to make it congruent with your intended target. Dave Cole REPLY TO: dbcole@colesoft.com Cole Software WEB PAGE: http://www.colesoft.com 736 Fox Hollow Road VOICE: 540-456-8536 Afton, VA 22920 FAX: 540-456-6658
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From: David Cole <dbcole@colesoft.com>
Newsgroups: bit.listserv.asm370
Subject: Re: assembly-language coding conventions (using patch areas)
Date: Sun, 4 Sep 2005 12:28:16 -0400
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