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diff --git a/2020/subtitles/emacsconf-2020--27-state-of-retro-gaming-in-emacs-chip8--vasilij-wasamasa-schneidermann-autogen.sbv b/2020/subtitles/emacsconf-2020--27-state-of-retro-gaming-in-emacs-chip8--vasilij-wasamasa-schneidermann-autogen.sbv deleted file mode 100644 index c88c3ded..00000000 --- a/2020/subtitles/emacsconf-2020--27-state-of-retro-gaming-in-emacs-chip8--vasilij-wasamasa-schneidermann-autogen.sbv +++ /dev/null @@ -1,912 +0,0 @@ -0:00:00.880,0:00:04.520 -hello everyone and welcome to my talk - -0:00:02.879,0:00:06.960 -state of retrogaming and Emacs - -0:00:04.520,0:00:08.639 -[Music] - -0:00:06.960,0:00:12.000 -first of all a little bit about myself - -0:00:08.639,0:00:13.599 -my name is neilman I'm 28 years old - -0:00:12.000,0:00:15.200 -I work as a cyber security consultant - -0:00:13.599,0:00:17.440 -msg systems and - -0:00:15.200,0:00:19.359 -test other people's web applications and - -0:00:17.440,0:00:20.160 -review the source code for security - -0:00:19.359,0:00:22.960 -problems - -0:00:20.160,0:00:25.039 -you can reach me by email I have my own - -0:00:22.960,0:00:26.480 -self-hosted git repositories - -0:00:25.039,0:00:28.480 -and I have a blog where you can - -0:00:26.480,0:00:32.160 -occasionally find new posts by me on all - -0:00:28.480,0:00:34.800 -kinds of things not just emix things - -0:00:32.160,0:00:36.480 -so but the motivation about this one I - -0:00:34.800,0:00:38.079 -found that Emacs is the ultimate - -0:00:36.480,0:00:40.160 -procrastination machine and there are - -0:00:38.079,0:00:41.200 -lots of fun demonstrations I'll go over - -0:00:40.160,0:00:44.160 -a few of them - -0:00:41.200,0:00:46.079 -for example someone made a thing to - -0:00:44.160,0:00:48.239 -order sell it for himself online so it - -0:00:46.079,0:00:50.879 -doesn't have to walk over to the shop - -0:00:48.239,0:00:51.760 -there's plenty rc bots there's some game - -0:00:50.879,0:00:53.520 -things - -0:00:51.760,0:00:55.600 -there's an emulator for the z machine - -0:00:53.520,0:00:57.600 -which you can use to play zorg - -0:00:55.600,0:00:59.039 -and so I asked myself at this point can - -0:00:57.600,0:01:01.039 -you actually emulate retro games at - -0:00:59.039,0:01:02.800 -60fps and it looked around a bit - -0:01:01.039,0:01:04.479 -and found some projects but none that - -0:01:02.800,0:01:07.360 -were actually able to - -0:01:04.479,0:01:08.000 -do it at 60fps so I set out to do my own - -0:01:07.360,0:01:09.439 -one - -0:01:08.000,0:01:11.119 -and looked out for a console that you - -0:01:09.439,0:01:13.439 -can actually emulate at that speed - -0:01:11.119,0:01:14.690 -using emax with its very very limited - -0:01:13.439,0:01:16.320 -rendering - -0:01:14.690,0:01:19.520 -[Music] - -0:01:16.320,0:01:20.560 -and here's the project chip8.el it's - -0:01:19.520,0:01:22.880 -pretty much finished - -0:01:20.560,0:01:24.000 -it clocks into under 1000 sourced lines - -0:01:22.880,0:01:26.159 -of code - -0:01:24.000,0:01:28.080 -it supports the superchip 8 extensions - -0:01:26.159,0:01:30.159 -it runs at full speed all games behave - -0:01:28.080,0:01:32.320 -okay as far as I'm concerned and - -0:01:30.159,0:01:34.479 -yeah I'm pretty happy with it it's very - -0:01:32.320,0:01:37.040 -much the hell world of emulation - -0:01:34.479,0:01:40.880 -and I might maybe do some other - -0:01:37.040,0:01:43.360 -emulation projects in the future - -0:01:40.880,0:01:45.439 -now for the section which is the longest - -0:01:43.360,0:01:46.320 -bunch of fun facts about ship a dot el - -0:01:45.439,0:01:49.759 -which I've learned - -0:01:46.320,0:01:52.240 -during this project so - -0:01:49.759,0:01:54.640 -what the hell is debate anyway first of - -0:01:52.240,0:01:56.799 -all unlike many other emulation game - -0:01:54.640,0:01:58.560 -things it's not a console but a vm - -0:01:56.799,0:02:00.000 -it was designed for easy parting of home - -0:01:58.560,0:02:02.560 -computer games - -0:02:00.000,0:02:03.680 -it wasn't terribly successful and but - -0:02:02.560,0:02:04.320 -there's still a small community of - -0:02:03.680,0:02:06.079 -enthusiasts - -0:02:04.320,0:02:09.119 -writing games for it and there are even - -0:02:06.079,0:02:11.920 -a few demos - -0:02:09.119,0:02:14.720 -this vm has system specs it has a very - -0:02:11.920,0:02:14.959 -very simple 8-bit cpu with 16 registers - -0:02:14.720,0:02:17.760 -and - -0:02:14.959,0:02:18.160 -36 fixed size instructions you have a - -0:02:17.760,0:02:20.560 -whole - -0:02:18.160,0:02:22.080 -4 kilobyte of ram you have a stack with - -0:02:20.560,0:02:24.480 -16 return addresses - -0:02:22.080,0:02:25.760 -the resolution is 64 by 32 black white - -0:02:24.480,0:02:28.000 -pixels - -0:02:25.760,0:02:29.440 -rendering is done by drawing sprites - -0:02:28.000,0:02:30.160 -these are drawn in excel mode meaning - -0:02:29.440,0:02:32.239 -that if you - -0:02:30.160,0:02:33.840 -draw a sprite and set a bit it just - -0:02:32.239,0:02:35.040 -flips over from black to white or white - -0:02:33.840,0:02:36.560 -to black - -0:02:35.040,0:02:38.239 -first one you have a modern buzz that - -0:02:36.560,0:02:40.640 -can just beep at one - -0:02:38.239,0:02:43.120 -frequency and most unusually there's a - -0:02:40.640,0:02:45.360 -hexadecimal keypad as input - -0:02:43.120,0:02:48.160 -so the keys are basically zero to nine - -0:02:45.360,0:02:48.160 -and a to f - -0:02:48.480,0:02:52.400 -so how does this whole thing work it - -0:02:50.879,0:02:53.599 -runs an unspecified speed - -0:02:52.400,0:02:54.879 -you'll probably have to do some fine - -0:02:53.599,0:02:56.080 -tune you find the speed you're happy - -0:02:54.879,0:02:58.560 -with - -0:02:56.080,0:03:01.120 -sound and delay timers exist they count - -0:02:58.560,0:03:02.879 -down at 60fps down to zero - -0:03:01.120,0:03:05.120 -this is done so that you can play a - -0:03:02.879,0:03:06.640 -sound at some specific time - -0:03:05.120,0:03:08.640 -the game itself is loaded with a fixed - -0:03:06.640,0:03:10.480 -offset into ram the program account is - -0:03:08.640,0:03:11.920 -set to exactly that offset - -0:03:10.480,0:03:13.840 -and from there it enters the game loop - -0:03:11.920,0:03:15.519 -where decodes and instruction executes - -0:03:13.840,0:03:18.130 -it for the side effects and just - -0:03:15.519,0:03:19.599 -loops and does this at infinitum - -0:03:18.130,0:03:21.920 -[Music] - -0:03:19.599,0:03:23.920 -so the game was the first thing where - -0:03:21.920,0:03:24.239 -into problems the usual game approach is - -0:03:23.920,0:03:26.640 -to - -0:03:24.239,0:03:28.239 -do stuff figure out how long to eight - -0:03:26.640,0:03:30.640 -wait for exactly that much and - -0:03:28.239,0:03:31.680 -repeat this doesn't work well in imax at - -0:03:30.640,0:03:34.959 -all because well - -0:03:31.680,0:03:37.280 -user input basically and - -0:03:34.959,0:03:39.040 -Emacs is designed to just do whatever it - -0:03:37.280,0:03:40.080 -needs to do whenever you enter use input - -0:03:39.040,0:03:42.799 -instead of - -0:03:40.080,0:03:43.440 -doing things at one specific time if you - -0:03:42.799,0:03:45.040 -try to do - -0:03:43.440,0:03:46.640 -interruptable sleep well you get - -0:03:45.040,0:03:49.440 -unpredictable behavior - -0:03:46.640,0:03:50.959 -for example can be the timer doesn't run - -0:03:49.440,0:03:52.560 -at all at next time because you've - -0:03:50.959,0:03:54.400 -accidentally cancelled it - -0:03:52.560,0:03:55.760 -if you do uninterruptable sleep it's - -0:03:54.400,0:03:56.720 -freezes instead which isn't what you - -0:03:55.760,0:03:59.360 -want either - -0:03:56.720,0:04:00.560 -so I went for timers which forced me to - -0:03:59.360,0:04:02.159 -do inversion of control - -0:04:00.560,0:04:04.080 -meaning that I have to write code in the - -0:04:02.159,0:04:06.159 -style where it's just call it - -0:04:04.080,0:04:07.200 -time and this allows this input to - -0:04:06.159,0:04:09.120 -happen and to - -0:04:07.200,0:04:11.040 -for things to progress at roughly the - -0:04:09.120,0:04:12.879 -speed I want to - -0:04:11.040,0:04:14.159 -so there's the skydiver function which - -0:04:12.879,0:04:16.000 -is called a 60fps - -0:04:14.159,0:04:17.359 -and I have to be very careful to not do - -0:04:16.000,0:04:20.479 -too much in it - -0:04:17.359,0:04:22.960 -and say this function execute cpu cycles - -0:04:20.479,0:04:23.680 -decrypt the sound delay registers and - -0:04:22.960,0:04:27.759 -redraw - -0:04:23.680,0:04:28.800 -the screen so to map this whole system - -0:04:27.759,0:04:31.199 -to mx lisp - -0:04:28.800,0:04:33.120 -I've used just integers and vectors - -0:04:31.199,0:04:35.040 -which contain even more integers - -0:04:33.120,0:04:37.759 -this is used for the ram registers - -0:04:35.040,0:04:39.120 -return stack key state screen and so on - -0:04:37.759,0:04:41.520 -and so forth basically - -0:04:39.120,0:04:42.800 -what you would do if you were writing c - -0:04:41.520,0:04:44.560 -all of this is stored in global - -0:04:42.800,0:04:46.479 -variables I'm not using any - -0:04:44.560,0:04:48.400 -lists at all and as a side effect - -0:04:46.479,0:04:50.320 -there's no constant going on at all - -0:04:48.400,0:04:51.120 -there are no extra objects created which - -0:04:50.320,0:04:53.919 -would trigger - -0:04:51.120,0:04:55.840 -garbage collection pulses this getting - -0:04:53.919,0:04:56.720 -this red was rather tricky actually and - -0:04:55.840,0:04:58.560 -there were some - -0:04:56.720,0:05:01.680 -in garbage collection problems which I - -0:04:58.560,0:05:01.680 -had to resolve over time - -0:05:01.759,0:05:05.520 -so the coding instructions for this you - -0:05:04.320,0:05:06.800 -have to know that all instructions are - -0:05:05.520,0:05:08.880 -two bytes long - -0:05:06.800,0:05:10.240 -and the arguments encoded inside them - -0:05:08.880,0:05:11.440 -for example the jump to address - -0:05:10.240,0:05:15.120 -instruction - -0:05:11.440,0:05:18.400 -is encoded as one and three hex digits - -0:05:15.120,0:05:20.800 -the type is extracted masking with f000 - -0:05:18.400,0:05:21.680 -and then shifting it by 12 bits mask - -0:05:20.800,0:05:24.000 -means the hd - -0:05:21.680,0:05:25.440 -performance binary end you can do the - -0:05:24.000,0:05:26.639 -same with the argument basement with - -0:05:25.440,0:05:29.520 -zero fff - -0:05:26.639,0:05:31.039 -and no shift if you do this long enough - -0:05:29.520,0:05:32.639 -you'll find common patterns for example - -0:05:31.039,0:05:35.280 -addresses are always encoded like this - -0:05:32.639,0:05:36.880 -using the last three nibbles in the code - -0:05:35.280,0:05:38.400 -you'll find a big count which dispatches - -0:05:36.880,0:05:40.070 -on the type and executes it for the side - -0:05:38.400,0:05:41.440 -effects - -0:05:40.070,0:05:43.440 -[Music] - -0:05:41.440,0:05:45.919 -for testing I've initially just accused - -0:05:43.440,0:05:47.280 -the rom until I fit ctrl g - -0:05:45.919,0:05:49.039 -and then use the debug command to run - -0:05:47.280,0:05:51.360 -the screen to a buffer - -0:05:49.039,0:05:52.320 -later on I found tiny roms that just - -0:05:51.360,0:05:55.680 -display a static - -0:05:52.320,0:05:57.280 -test screen for example logo and looked - -0:05:55.680,0:05:59.199 -whether it looked right - -0:05:57.280,0:06:00.960 -I added instructions as needed and went - -0:05:59.199,0:06:03.360 -through more and more and more roms and - -0:06:00.960,0:06:05.199 -later I wrote in unit test suite as a - -0:06:03.360,0:06:06.000 -safety net and this unit test suite it - -0:06:05.199,0:06:08.400 -just - -0:06:06.000,0:06:10.080 -sets up an empty emulator state executes - -0:06:08.400,0:06:10.400 -some instructions and then looks whether - -0:06:10.080,0:06:13.840 -the - -0:06:10.400,0:06:13.840 -expected side effects have happened - -0:06:14.880,0:06:19.120 -for debugging I usually use e-debug but - -0:06:17.120,0:06:20.880 -this was super ineffective because well - -0:06:19.120,0:06:22.960 -you don't really want to step through - -0:06:20.880,0:06:24.960 -big cons doing side effects for every - -0:06:22.960,0:06:26.880 -single cycle when it can take like 100 - -0:06:24.960,0:06:29.680 -cycles for things to happen - -0:06:26.880,0:06:31.360 -therefore I've set up logging and - -0:06:29.680,0:06:32.720 -whenever I locked something - -0:06:31.360,0:06:33.919 -and couldn't figure out the error I - -0:06:32.720,0:06:37.039 -compared my lock output with - -0:06:33.919,0:06:39.199 -instrumented version of another emulator - -0:06:37.039,0:06:40.880 -and if the locks diverge then I have - -0:06:39.199,0:06:42.720 -figured out where the bug lies and could - -0:06:40.880,0:06:44.479 -look deeper into it - -0:06:42.720,0:06:46.639 -future project idea might be a chip 8 - -0:06:44.479,0:06:50.720 -debugger but I doubt I'll ever - -0:06:46.639,0:06:52.639 -go into it for analysis I initially - -0:06:50.720,0:06:54.400 -wrote a disassembler which is a very - -0:06:52.639,0:06:56.160 -simple thing but super tedious - -0:06:54.400,0:06:57.599 -especially if you wanted to add advanced - -0:06:56.160,0:06:59.120 -functionality for example analysis or - -0:06:57.599,0:07:00.000 -thinking of what part is data what had - -0:06:59.120,0:07:01.840 -this code - -0:07:00.000,0:07:03.360 -and I had this great idea for using the - -0:07:01.840,0:07:05.120 -radari 2 framework - -0:07:03.360,0:07:06.479 -and adding analysis and disassembly - -0:07:05.120,0:07:08.400 -plug-in for it - -0:07:06.479,0:07:10.319 -so I looked into this found okay here - -0:07:08.400,0:07:12.160 -where you can write plugins in c - -0:07:10.319,0:07:13.520 -but also in python so I wrote one in - -0:07:12.160,0:07:15.039 -python and then the scout there's - -0:07:13.520,0:07:17.440 -actually existing one in core which you - -0:07:15.039,0:07:19.599 -have to enable explicitly by passing its - -0:07:17.440,0:07:21.840 -argument so I've tried it and found it's - -0:07:19.599,0:07:23.680 -not exactly as good as my own one so - -0:07:21.840,0:07:26.610 -improved this one and submitted pull - -0:07:23.680,0:07:28.080 -requests until it was at the same level - -0:07:26.610,0:07:30.160 -[Music] - -0:07:28.080,0:07:31.360 -rendering was the trickiest part of this - -0:07:30.160,0:07:34.319 -whole thing because - -0:07:31.360,0:07:35.759 -well I decided against using a library - -0:07:34.319,0:07:37.120 -not like there would have been any - -0:07:35.759,0:07:39.599 -usable library for this - -0:07:37.120,0:07:41.680 -my usual approach of accelerating svg - -0:07:39.599,0:07:45.120 -file was too expensive it just created - -0:07:41.680,0:07:47.360 -too much garbage and took too long time - -0:07:45.120,0:07:49.599 -I then tried creating mutating strings - -0:07:47.360,0:07:52.639 -this was either either too expensive - -0:07:49.599,0:07:55.039 -just like svgs or too complicated I - -0:07:52.639,0:07:57.280 -tried changing svg tiles which created - -0:07:55.039,0:07:59.520 -gaps between the lines - -0:07:57.280,0:08:00.720 -then I tried to create an xpm file which - -0:07:59.520,0:08:02.400 -was backed by a bull vector - -0:08:00.720,0:08:04.400 -administrating this bull vector - -0:08:02.400,0:08:06.879 -but the image caching effect made it - -0:08:04.400,0:08:10.000 -just every nth frame to appear which - -0:08:06.879,0:08:11.440 -wasn't good either then I had the idea - -0:08:10.000,0:08:13.280 -to just use plain text - -0:08:11.440,0:08:14.800 -and paint the individual characters with - -0:08:13.280,0:08:17.120 -a different background color this - -0:08:14.800,0:08:18.479 -this had perfect perfect performance - -0:08:17.120,0:08:20.000 -there were many optimization attempts - -0:08:18.479,0:08:21.840 -until I got there and it was - -0:08:20.000,0:08:23.199 -very very stressful I wasn't sure - -0:08:21.840,0:08:26.160 -whether I would ever get to accept the - -0:08:23.199,0:08:28.560 -performance at all - -0:08:26.160,0:08:30.319 -for sound you only need to a single beep - -0:08:28.560,0:08:31.280 -so technically it shouldn't be difficult - -0:08:30.319,0:08:33.519 -to emulate it - -0:08:31.280,0:08:34.880 -however doing this is hard because Emacs - -0:08:33.519,0:08:37.200 -officially only supports synchronous - -0:08:34.880,0:08:39.039 -playback of sounds - -0:08:37.200,0:08:41.360 -but there's also emax process which you - -0:08:39.039,0:08:43.519 -can launch in asynchronous way - -0:08:41.360,0:08:45.279 -so I looked into it and found that - -0:08:43.519,0:08:46.640 -employee has a slave mode and mpv - -0:08:45.279,0:08:50.880 -supports listing on the - -0:08:46.640,0:08:54.000 -fifo for commands so I've created a pipe - -0:08:50.880,0:08:55.519 -started a past mpv in loop mode and - -0:08:54.000,0:08:58.000 -always send in pause and pause command - -0:08:55.519,0:09:01.839 -to the fifo and that way I could control - -0:08:58.000,0:09:01.839 -when to start beeping and stop beeping - -0:09:02.640,0:09:07.200 -so yeah that's it so far was a very - -0:09:05.760,0:09:09.279 -educational experience - -0:09:07.200,0:09:10.320 -I have tried out a bunch of games which - -0:09:09.279,0:09:12.640 -were - -0:09:10.320,0:09:14.320 -well I almost say the worst ports of - -0:09:12.640,0:09:15.839 -classic games I've ever tried - -0:09:14.320,0:09:18.320 -it wasn't terribly fun to play them but - -0:09:15.839,0:09:21.760 -was fun to improve the emulator until - -0:09:18.320,0:09:23.279 -well things worked good enough - -0:09:21.760,0:09:25.120 -and I've learned a lot about how - -0:09:23.279,0:09:27.760 -computers work at this level - -0:09:25.120,0:09:28.880 -so maybe maybe I'll in the future make - -0:09:27.760,0:09:31.920 -another emulator - -0:09:28.880,0:09:34.000 -but uh I'm not sure whether anything - -0:09:31.920,0:09:36.560 -more advanced like intel 8080 emulator - -0:09:34.000,0:09:37.839 -will actually run mix fast enough - -0:09:36.560,0:09:39.200 -but it's still an interesting idea - -0:09:37.839,0:09:39.600 -because then you could actually have an - -0:09:39.200,0:09:41.680 -os - -0:09:39.600,0:09:43.120 -inside Emacs and fulfill that one - -0:09:41.680,0:09:45.440 -specific meme - -0:09:43.120,0:09:47.279 -but if I try to do most serious stuff - -0:09:45.440,0:09:48.000 -I'll probably use chicken scheme which - -0:09:47.279,0:09:49.920 -is my - -0:09:48.000,0:09:53.279 -preferred language for serious projects - -0:09:49.920,0:09:57.839 -and writing neso gamer emulator - -0:09:53.279,0:09:57.839 -and that's it thank you - |