On (22 Jan 95) [EMAIL PROTECTED] wrote to All... > OAA00488 for sam-users-outgoing; Sun, 22 Jan 1995 14:12:50 +0100 > [131.111.8.33]) by sabre-wulf.nvg.unit.no (8.6.9/8.6.9) with SMTP id > OAA00483 for <[email protected]>; Sun, 22 Jan 1995 14:12:39 +0100 > Date: Sun, 22 Jan 1995 13:10:45 +0000 (GMT) > From: Steve Taylor <[EMAIL PROTECTED]>
> On 22 Jan 1995, Johnathan Taylor wrote: > In my unix-like system, which only has the single application entry point, > I'll use the LINE interupt to increment tasks-ticks and it simply switches > OFF the line interupt on entry to the OS and restores it again on exit back > to the task. > That's how I'm working it at the moment, but using the frame int. The only difference though is the important one that the SAM system ROM has multiple entry-points rather than a single RST with magic numbers for system function required... can make it more dificult to maintain proper control:-( >> Or you could store initial FP stack parameters on initial switching in a >> task and defer the next context switch until the FP stack is returned to >> its entry size > That isn't a problem at the moment - besides, DPL optimises its FPC calls > in such a way that there might very well be things lying on the stack for > ages, waiting to be used. It would be a very un-flexible way of doing > things. That would definatly mess up the task switching.... Si mentioned somthing about the Floating point library ala Small-C.... There's also another one in Hi-Tech C for CP/M-z80... though as yet I've not had to use it as *Most* applications can be implemented in integer maths:-) >> Oh can't you re-direct the frame interupt to driver whilst the roms paged >> in using FRAMIV at 5AE2H to allow you to maintain control in driver? > Yeah, but not safely during FPC execution - Suppose two tasks want to use > some FP at the same time. If we were to try and switch during an FP call > (remember that the ROM is not really designed for this) lots of nasty > system vars etc. need to be stored, updated etc, and I really want to > avoid this kind of thing. Use the RST38 redirection to keep track of 'ticks' and hooks via RST28V to keep track of FPC progress to determine a neutral point at which a context switch can occour and then swap stacks and FPC BREG or is that BCREG and it's six 5byte memories plus anything else that's important:-) As you say the ROM was not designed to share itself so you'll have to swap everything that makes it not work, sorry. This DPL compiler of yours.... How much like compiling stuff under C is it? It could be useful for equiping the sam-nativ'ish mode with the many standard utils whose only other options would be to either crawl along in a BASIC port or be written in machine code which is a bit of a pain IMHO Regards Johnathan ... (((((YOU)))))((((ARE))))(((((FEELING)))))(((((SLEEPY))))) -- |Fidonet: Johnathan Taylor 2:2501/307.9 |Internet: [EMAIL PROTECTED] | | Standard disclaimer: The views of this user are strictly his own.
