Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!elroy.jpl.nasa.gov!news.arc.nasa.gov!vsi1!zorch!amiga0!mykes From: mykes@amiga0.SF-Bay.ORG (Mike Schwartz) Newsgroups: comp.sys.amiga.programmer Subject: Re: Information on Amiga Technical Reference Seri Message-ID: Date: 16 Jun 91 20:58:39 GMT References: <21956@cbmvax.commodore.com> <1603@glyph.kingston.ny.us> <1991Jun3.140107.945@csc.canterbury.ac.nz> <1057.284e0dbf@vger.nsu.edu> <91158.110654GHGAQA4@cc1.kuleuven.ac.be> <1062.2853935b@vger.nsu.edu> andy@cbmvax.commodore.com (Andy Finkel) writes: >>In other words, the Amiga OS makes over 400 functions (more under 2.0) public, while >>Lemmings et al make none public. There is the difference. > >Except we'd like people to program to the external interface of the >OS, rather than to the internal workings. Having the source available >is often educational in the wrong way. "Knowing" that register A5 is >free, or that a routine happens to not touch A1 is the usual outcome. > I wouldn't recommend that anyone ever rely on "knowing" that registers are used or not. If you do want to ensure that your APP will work with future releases of the OS, and you MUST rely on the way the current implementation of the OS works, you could cut and paste the routine from the OS sources into the APP. Carrying along the extra baggage (duplicate of a routine in ROM) is the price the app programmer decides to pay. Again, there are also routines in the ROM that CAN be used to do what you want, but aren't ideal. I used the example of BltMaskBitMapBitMap() in an earlier post... You could emulate such a routine with 2 BltBitMap() calls, but you pay a serious price in speed. Calling BltMaskBitMapRastPort() is not an answer, either, because it is even slower than 2 BltBitMap() calls :) It would be much easier for an application programmer to go and hack BltBitMap() so that it took fewer parameters (faster calling convention), and used 3 inputs instead of 2... >> >>By the way, I wouldn't mind it if publishers did indeed publish source to their >>games (after sales diminish, of course). When I do games under contract, the contracts specifically forbid me from publishing the sources. It would be up to the publishers to decide... -- **************************************************** * I want games that look like Shadow of the Beast * * but play like Leisure Suit Larry. * ****************************************************