PC World 1999 June

home *** CD-ROM | disk | FTP | other *** search

/ PC World 1999 June / PCWorld_1999-06_cd.bin / software / temacd / winuae / WinUAE088R4.exe / uninst.exe < prev

Wrap

Text File | 1999-05-11 | 15.9 KB | 306 lines

You can help to make this program better. If you fix bugs or implement new features, I'd be grateful if you send me patches. For a list of interesting projects, and for a brief summary on how UAE works, see below. A few guidelines for anyone who wants to help: - Please contact me first before you implement major new features. Someone else might be doing the same thing already. This has already happened :-( Even if no one else is working on this feature, there might be alternative and better/easier/more elegant ways to do it. - If you have more than one Kickstart, try your code with each one. - Patches are welcome in any form, but diff -u or diff -c output is preferred. If I get whole source files, the first thing I do is to run diff on it. You can save me some work here (and make my mailbox smaller). Some possible projects, in order of estimated difficulty: - Add gamma correction - If the serial port still isn't working (I've got no idea, I don't use it), fix it. - Someone with a 68020 data sheet might check whether all opcodes are decoded correctly and whether all instructions really do what they are supposed to do (I'm pretty sure it's OK by now, but you never know...). - Add more 2.0 packets to filesys.c - Multi-thread support is there now, it just needs someone to test it on a SMP machine and to fix it so it improves speed instead of slowing the thing down. - Improve the Kickstart replacement to boot more demos. - Snapshots as in CPE. Will need to collect all the variables containing important information. Fairly easy, but boring. (Use core dumps instead :-) _If_ someone attempts this, please be more clever than the various CPC emulators and dump state only at one fixed point in the frame, preferrably the vsync point. Also talk with Petter about this. - Find out why uae.device has to be mounted manually with Kick 1.3. The problem seems to be that we don't have a handler for it. I _think_ what we need is the seglist of the standard filesystem handler. Problem is, DOS hasn't been started when the devices are initialized and so we can't get to the DosBase->RootNode->FileHandlerSeg pointer, and then there is the confusing matter of BCPL GlobVecs and other weird stuff... - Some incompatibilities might be fixed with user-modifiable fudge variables the same way it's done in various C64 emulators. - With the new display code, it would probably be easier than before to implement ECS resolutions - however, a lot of places rely on the OCS timing parameters and display sizes. - Figure out a diskfile format that supports every possible non-standard format. - Implement 68551 MMU. I have docs now. Not among the most necessary things. Should be done like exception 3 handling: add code to genamode in gencpu.c. - Implement AGA support. Some bits and pieces exist. - Reimplement Amiga OS. (Well-behaved) Amiga programs could then be made to use the X Window System as a "public screen". Of course, not all the OS would have to be re-done, only Intuition/GFX/Layers (which is enough). [Started, look at gfxlib.c - not usable yet.] - Find some extremely clever ways to optimize the smart update methods. Some ideas: a) Always use memcmpy() to check for bitplane differences. If no differences are found, see if BPLxDELAY got modified, if so, scroll. Problems: * You'd still have to draw a few pixels around the DIW borders. Not very hard. * Scrolling with memcpy in video memory can be terribly slow (no, I shouldn't have bought the cheaper video card with DRAMs) * At least every 15 pixels a full update has to be done since the bitplane pointers get updated after that. And that's with the slowest scrolling - if the playfield scrolls faster, the benefit converges against zero. You could also do vertical scrolling tests, but similar problems arise - where should one check? One line above/below? What about faster scrolling? You could use the bitplane pointers as hints, but with double/triple buffering this gets problematic, too. On the whole, I don't think it would be worth the effort, even if it works very well for a few games. b) Well, there is no b). If I thought of something I forgot it while writing a). - Port it to Java and Emacs Lisp - A formal proof of correctness would be nice. Source file layout src/ contains (mostly) machine-independent C code. include/ contains header files included by C code. md-*/ CPU and compiler dependent files, linked to machdep by configure od-*/ operating system dependent files, linked to osdep by configure td-*/ thread library dependent files, linked to threaddep by configure sd-*/ Sound code. sd-* is only for sound systems which are not OS specific or for which no "od-*" directory exists. Linked to sounddep targets/ Contains header files which contain some information about which options a specific port of UAE understands. Coding style As long as your code is hidden in a file buried in md-*/ or od-*/ where I never have a look at it, you can probably get away with not following these guidelines. * Do not include CR characters. * Do not use GNU C extensions if you can't hide them in a macro or in a system-specific file so that an alternative implementation is available when GNU C is not used. This applies to _all_ OS/CPU/compiler specific details. Basically, nothing of that sort should appear in src/*.c (we're a bit away from that goal at the moment, but it's getting better). * Make sure your code does not make assumption about type sizes other than the minimum widths allowed by C. If you need specific type sizes, use the uae_u32 type and its friends. * Set up your editor so that tab characters round up to the next position where ((cursorx-1) % 8) == 0, i.e. 8 space tabs. Do not use 4 space tabs, that makes the code awful to read on other machines and worse to edit. (I'm talking about the tab character here, not indentation!) * Lines can be up to 132 characters wide. Use SVGATextMode for the Linux console, or use a windowing system in a high resolution. * C++ comments are a no-no in C code. * Indentation - look at some code in custom.c and try to follow it. Don't use GNU 2-space-in-weird-places indentation, I find it awful. But _do_ follow the GNU rules for adding whitespace in expressions, and those for breaking up multiple-line if statements. Fixed indentation rules almost never make sense - break the rules if that makes your code more readable. Hint: Get jed from space.mit.edu, /pub/davis. It can indent your code automatically. Put the following into your .jedrc, and it will come out right: C_INDENT = 4; C_BRACE = 0; C_BRA_NEWLINE = 0; C_Colon_Offset = 1; C_CONTINUED_OFFSET = 4; How it works Let's start with the memory emulation. All addressable memory is split into banks of 64K each. Each bank can define custom routines accessing bytes, words, and longwords. All banks that really represent physical memory just define these routines to write/read the specified amount of data to a chunk of memory. This memory area is organized as an array of uae_u8, which means that those parts of the emulator that want to access memory in a linear fashion can get a (uae_u8 *) pointer and use it to circumvent the overhead of the put_*() and get_*() calls. That is done, for example, in the pfield_doline() function which handles screen refreshes. Memory banks that represent hardware registers (such as the custom chip bank at 0xDF0000) can trap reads/writes and take any necessary actions. To provide a good emulation of graphical effects, only one thing is vital: Copper and playfield emulation have to be kept absolutely synchronous. If the copper writes to (say) a color register in a specific cycle, the playfield hardware needs to use the new information in the next word of data it processes. UAE 0.1 used to call routines like do_pfield() and do_copper() each time the CPU emulator had finished an instruction. That was one of the reasons why it was so slow. Recent versions try to draw complete scanlines in one piece. This is possible if the copper does not write to any registers affecting the display during that scanline. Therefore, drawing the line is deferred until the last cycle of the line. However, sometimes a register which affects how the screen will look is modified before the end of the line (think of copper plasmas). That's what "struct decision thisline_decision" is for. It is initialized at the start of each line. During the line, whenever a vital register is changed, one of the decide_*() functions is called and may modify thisline_decision. There are several independent decisions: - which DIW should be used - where does data fetch start/stop (or is the line in the border altogether) - where should sprites be drawn (note: the same sprite can appear more than once on one scanline, see Turrican I world 3 levels 1 and 3 for the best example) - what are the playfield pointers at the start of DDF. Related, what data do they point to. - what are the playfield modulos at the end of DDF - coppermagic with the colors is remembered for later use - so is copper magic with the bitplane delay values. I used to think there was no useful application for modifying BPLCON1 while data is being displayed, but Sanity demos can make Amiga emulator programmers look real old. All of this is remembered while the raster line is processed by the hardware. After the line (at hsync), all the decisions are made if they weren't made before. At that point the line can be drawn by playfield_draw_line. Additionally, all the decisions from the previous displayed frame are saved and compared with the new ones, since often lines are not modified between frames. This saves a lot of redrawing work. The CPU emulator no longer has to call all sorts of functions after each instruction. Instead, it keeps a list of events that are scheduled (timer interrupts, hsync and vsync events) and their "arrival time". Only the time for the next event is checked after each CPU instruction. If it's higher than the current cycle counter, the CPU can continue to execute. Things that can't be supported with the current "decision" model: - Changes in lores/hires mode during one line. Dunno whether that was ever used in reality. - Changes to the bitplane DMA bit during one line. Hardly useful and not likely to be used. [but there are at least two programs which do ugly things like that, and there are some hacks in UAE that make those programs work (Magic 12 Ray of Hope 2 is one of these demos)] - Changes in bitplane data during one line. If programs do this kind of thing, it's most likely accidental and the program is broken. Can happen with programs that use the blitter incorrectly, like all the Andromeda demos. - others? (fill in if you can think of anything) All in all, it's unlikely that this causes compatibility problems. If it does, fudge values could be introduced (although that sort of thing gets messy quickly). * Native code vs. 68k code It is possible to call native code from 68k code; autoconf.c has some routines which make setting up a call trap very easy. However, it is not as easy to call 68k code from native C code, at least not while Amiga Exec multitasking is running. You ask why? Amiga process1 calls native function foo Native function foo calls some 68k function and goes into 68k mode Amiga context switch happens, process1 is put to sleep and process2 gets run. Amiga process2 calls native function foo Native function foo calls some 68k function and goes into 68k mode Amiga context switch happens, process2 is put to sleep and process1 gets run. Process 1 completes the 68k function called by foo and returns from 68k mode. There. Now we are in function foo again. When it called the 68k code, process2 was active. Now process1 is active, and the function we called in process2 hasn't completed yet. What a mess. To get around this, you need to do some stack magic. Code to do this exists, but it must be adapted for each port, since setting up a different stack is completely non-portable. * How multithreading in filesys.c works AmigaOS is nice enough to start one processes for each mounted filesystem. All of these run in the 68k emulation code, i.e. in the main UAE thread. This is the reason why multithreading is desirable: if the main UAE thread blocks waiting for I/O, the CPU emulation can't continue to run. Since the Amiga OS is capable of multi-tasking, it is possible that other code could run until the I/O operation is complete. The most important bit of code that can run is the code that moves the mouse pointer - it's unpleasant if the pointer does not follow mouse movement during disk/CD accesses. When a packet is received by the filesys.asm code, filesys_handler is called. This function always runs in the main UAE thread. - In the single-threaded case, this function performs the action that was requested, then returns 0 to indicate "action completed, reply packet". Nothing else is performed. - In the multi-threaded case, filesys_handler figures out which unit the packet was for and sends the packet to the UAE thread responsible for handling this unit. filesys_handler returns 0 to indicate: queue the packet. Also, one (at that point unused) field in the packet is set to 0 to indicate that the action was not completed. The latter case is the interesting one. The thread that got the packet does the following: - perform the action as usual - set the "command complete" field in the packet to -1. - send a message to the AmigaOS (!) filesystem process. However, it can't do that without some effort. We can't call 68k code from the emulator easily. So we have to use an Amiga interrupt. The filesystem init code sets up an Exec IntServer for the EXTER interrupt, and hsync_handler() checks periodically whether the filesystem needs an interrupt and raises one if necessary. Only one dummy message is used per filesystem unit, which is allocated at startup. This means that there must be some locking to prevent the unit thread from sending the same message twice to the same port. To determine whether the message is free, three counts are kept. "cmds_sent" is incremented by the UAE thread whenever it has completed a command. "cmds_acked" is set to the same value of cmds_sent at the point that the interrupt handler got invoked and decided it must send a message. Finally, cmds_complete is set to this value at the time the AmigaOS process receives the dummy message. Whenever cmds_acked == cmds_complete, the dummy message is free to be sent again. The EXTER interrupt basically walks through the units, looks at the cmds_* fields and sends the dummy message to the Amiga filesystem process when possible and necessary. When the Amiga filesystem process receives such a dummy message, it does the following: - increment cmds_complete as described above. - walk through the queue of unprocessed commands and see which ones now have a status of -1, indicating that they are finished. These are removed from the queue and replied to. * Calltraps at fixed locations F0FF00: return from 68k mode. F0FF10: must have gotten lost somewhere ;) F0FF20: used by filesys.c to store away some information from the startup packet. F0FF30: filesys_handler(). F0FF40: startup_handler(), handles only the startup packet for each filesystem. F0FF50: used by the EXTER interrupt which we set up for the filesystem. F0FF60: used by the uaectrl/uae-control programs (see uaelib.c) F0FF70: used by the task that gets set up for the mouse emulation. * How the compiler works .. yet to be written. To be decided, in fact. Portability This section was out of date. I'll rewrite it. Some day.