About

Michael Zucchi

 B.E. (Comp. Sys. Eng.)

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Friday, 28 December 2018, 09:53

Making biltong made easy

After a few iterations i've managed to get biltong making down to a pretty streamlined, 'somehwat lazy' process. It relies on the butcher (aka supermarket) doing the brining.

First get the spices ready. This is both important and a bit arbitrary. You can find recipes on the net but the main ingredients are coriander seed and black pepper (and those starting with 'one whole freshly butchered springbok' aren't very practical).

Here's a simple one. It was enough for two small batches.

Recipe for Biltong Spices
AmountIngredient
1 cupcoriander seed
1 tbspblack pepper
1 tbspallspice
1 tspfennel seed
1 handfuldried thai birds-eye hot chillies

Actually I didn't write it down so these numbers might be a bit off but it's about right. Thigs like allspice, fennel seeds, ginger, cinnamon, paprika, and so on can add a nice tweak to the basic recipe. I always add hot chillies as a matter of course, of course.

Not terribly important here but an Australian metric tablespoon is 4x teaspoons (20ml), not the usual 3 in the rest of the western world.

Ideally give them all a bit of a dry-roast in a pan or the oven to bring out the flavours. It isn't necessary but its worth it and it smells great. Basically just keep stirring over low-medium heat until they become aromatic and the chillies gain a bit of colour. Here i've just started roasting them.

Then powder them. If you have the time and the equipment using a mortar and pestle will produce a more aromatic powder; but i usually just use a blender and keep going until it's done. Don't breath it in if you've used any really hot chillies.

I also have a small precious supply of dried habaneros i made a few years ago and I threw a couple of those into the blender.

Next the meat. I wait till corned silverside is on special ($8/Kg) at my local Foodland and grab a couple of them. I try to get the largest ones they have (>1Kg), and given the packaging is often opaque its a bit hit and miss as to the quality you get - ideally good solid meat with little fat and gristle. Here i've just unpackaged them and wiped off the slimey brine residue, these are good cuts to use. Each one here is about 1.5Kg.

Corned silverside - corned beef - done this way is apparently an Australian thing (according to my butcher brother), so if you're from some backward arsed country that doesn't have this you'll have to do it the long way.

So you basically just slice it into roughty 2cm thick blocks and trim off most of the fat. It's reasonably easy to slice squarely because the brining makes it go stiffer than raw meat. I usually fry up the trimmings - its sort of like shit bacon, chewy but tasty.

So that's the hardest and messiest bit out of the way. If making it from scratch you would then brine this meat before moving to the next stage. And you have to be concerned about brine concentration or amount of salt (none of the recipes I found ever say how MUCH salt to use), and so on. I haven't found the pre-pickled meat to be completely consistent but it's always edible once completed. Sometimes it can be a bit on the salty side, but that just means you drink more beer.

`dip the slices of brined meat in vinegar'

aka fuck that. Pour half a cup of vinegar into the container, put the lid on, and shake the shit out of it. Drain.

'roll in the spices to cover evenly'

Pour about 1/2 a cup of the spice mix over the meat ...

Cover, and shake the shit out of it again. Done.

I used to have a bowl of vinegar i'd dip it in, then a tray of spice to do the coating. Messy as fuck and unreliable.

Actually i'm still working on getting the ideal coating, I always seem to put too much on because when you're applying it it doesn't look like much but when it's dry it's heavily coated and falling off. Next time I do it I might also try leaving it in this state in the fridge overnight to let the flavours seep in a bit more before starting to dry.

It took a while (literally years!) but i found a small local caterers shop that sold small stainelss steel butchers hooks. Previously i'd used fishing line (fucking pain to work with) then some stainelss steel wire I fashioned into hooks (which was ok until i found the proper ones). I bought out the shop at the time and got 13, which was just enough for this batch.

Hang them up on the hooks. I have a small cpu fan running off an old nokia charger to keep the air flowing to help speed up drying and a fly-screen to keep the bugs out. I used to have a small 20W incandescent lightglobe to help with the drying but they keep burning out and it isn't necessary in summer.

They're ready for 'picking' 1-2 weeks later depending on the weather and how thick you cut the meat. It will lose about 50% of it's original weight and be very dry and hard - you need a biltong cutter to get through it. I've tried stopping a bit earlier so it isn't so hard but the flavour is muted and it wont keep anywhere near as long.

Cut into as thin slices as you could be bothered with, consume with beer. If it's too thick it'll take a lot of chewing, if it's too thin just cutting it becomes a chore!

It lasts forever in the fridge. I made a batch just before getting gout a few years ago so didn't touch it for about a year - it was still ok when I finally got through it all.

Tagged cooking.
Friday, 28 December 2018, 08:46

Speaker Boxes and Music Players

I finally got around to mostly finishing the speakers I was making out of recovered drivers. Here's a bit of a photo-diary of the final stages.

Here we have the completed woodwork. It has been glued and sanded square. I'm mostly happy with how it turned out but I could have done a bit more sanding; I was over it by then. In each case I pretty much practiced on one and got better on the other one, hence a few differences here and there. The one on the left is unpainted and the one on the right has a coat of sanding sealer and also the binding post mounting mechanism.

Three undercoats, lots of sanding and two overcoats and it's ready to be put together.

Given the paint was so expensive ($90) I did a bit of a shit job in the end; I just got sick of dealing with everything. First I had a cheap throwaway brush which I should've just thrown away before I even started. Then the paint was too thick for the weather and needed more thinning, then I tried using a small roller - but again i got some cheap junk which left behind piles of dust and shit, and because I hadn't used a roller before I didn't apply it as well as I might have.

The next shot just shows the mounting point for the binding posts.

Even this I kinda fucked up. I tried using the drill press to drill the screw holes to mount it but to avoid scratching the paint I had it on a small block of foam. It moved when I wasn't looking and I drilled it in the wrong spot. It's hidden but I know it's there.

Soldering the wires.

Completed binding posts.

Connecting the driver.

Inserting the acoustic foam. I have 25mm at the read and 12.5mm down the sides - about as much as could fit in the small box.

A completed speaker (so far). The screws (all 24 of them) for the box are really only aesthetic as the box is very well glued. They did help when setting the glue though.

The pair. I've only redone the rubber surround on the right one so far, the one on the left is still a bit scratchy with high volume as a result. The mounting rubber washers/etc is still work in progress.

I'm still yet to get some fabric for the grilles. I did a quick peruse through lincraft but couldn't find any suitable, next time i'll ask and there's a couple of other places to try.

And finally a shot in testing. The plan is to put the electronics in another box with a battery pack. I've got the bits for the battery but am still working on the mechanics.

How do they sound? Well ok. They're not going to break any technical records; there's no engineering behind the boxes other than being a sealed box with a bit of foam in it. Each only has a woofer so the top-end is very retarded. The bottom end isn't too bad but it does have an echoey effect with some mid-tones, then again so do any other small speakers i've tried (including the $1000/pair units I just installed in the dining room). Quite ok for a bit of outside doof though!

It's been a good little project to get away from the screen so far, although finishing it off will not be.

Electronics and Software

I was looking around for hardware for the player but since I have the mele doing nothing I thought I may as well use that. Most of the other prototyping boards around now are either too high powered or missing some necessary bits; although the nanopi boards look quite attractive (on a side-note I can't believe how expensive raspberry pi shit is in australia). As this is nominally a 'portable' system based on recycled speakers (with no tweeters!) the audio quality isn't terribly important, the on-board dac/codec sounds good enough to me. I'm also considering an old phone or an old 7" tablet I have, although it's far less attractive to me if they can only run android (fuck that shit; yeah fuck you too google).

After spending most of a day on it I managed to get debian running on the mele. I tried the sunxi wiki and building my own kernel and bootloader but without any debug console I couldn't tell if it was working or not. I got this server image to work in the end, using the jessie image.

While trying to build using the sunxi instructions I discovered that the ubuntu maintainers have a really broken idea about what a cross-compiler should do. And they're really quite rude about it, hiding their rudeness behind the `code of conduct'.

To avoid dragging in gobs of junk and other poettering snot I built a basic SDL (1.2) and a cut-down ffmpeg (1.0) from source and have a basic console music player working. With a little more work I can control it with the mele airmouse although without a screen it's going to be difficult to do too many interesting things. Something to poke about with.

Tagged hacking, linux, workshop.
Thursday, 29 November 2018, 18:18

Dropper Fire Grill, and Firefox suxors too

So this came about because I was fighting with firefox and needed to get away from a screen for a while. I wrote a couple of plugins (oh sorry, 'addons', no hang on, web-extensions, WHATEVER THE FUCK YOU WANT TO CALL IT MOZILLA) and the experience was sour (can't you tell?).

The aforementioned BBQ/firepit thing I haven't gotten around to using yet, one reason is because I wanted to make a fire grate first because it's a bit too deep.

So a few droppers, a bit of hacksawing and some angle grinding later here it is. It just slots together with no fastening or welding.

It's even adjustable! No brick, brick flat, or brick on side!

Actually it might just work better as an esky, but i'll see.

More on the firefox plugins later, they're just for overriding site fonts and site colours. There do exist such plugins but they no longer work for some reason. OF course there's not much use distributing the source becuase you NEED A FUCKING MOZILLA ACCOUNT JUST TO INSTALL THEM.

Tagged rants, workshop.
Monday, 26 November 2018, 16:58

Putting things back together

My brother was here a few weeks ago and I took the opportunity of having transport (I don't drive - just never got a license) to get a few things that are a little difficult to transport on the bicycle.

One was to take my old VAF DC-7 Rev 1.0 speakers and get them reconditioned. It wasn't exactly cheap but they replaced the old drivers (required a bigger hole) and i'm not sure what else. But I asked to keep the old drivers just to muck around with, perhaps build a 'portable speaker' type thing out of them. They are a bit scratchy from uh, over-use, but I noticed the main problem is the surrounds had perished. I looked up some info about replacing them and ended up ordering some cheapies from China - i'm not sure I can recover them regardless and it's not worth the cost if I fail.

Part of the probess is removing the old rubber, and about all I can say about it is you have to be patient. I used a very sharp chisel and it took a couple of hours just to remove one, although the final 1/4 went much faster than the first once I got the technique sorted out.

Tools

Another thing I got was a welder, small drill press and some other tools. And that lead to a bit of a spending spree that continued after he left, buying a bunch of other workshop tools. They're mostly cheap bits and pieces because i'm not sure how much use i'll get out of them.

It wasn't the reason I got the welder but the first thing I thought of making was a belt buckle for a very wide kilt belt. I had asked a small leather work place (shoe repair, belts) shop in the city whether they could make wide belts but they couldn't and directed me to a saddlesmith at the other end of town. I dropped in one day and asked about it - yeah he could make any width belt, but he didn't have any buckles suitable. So the next weekend I got the welder out and turned a couple of pieces of wine barrel ring into a rather large belt buckle.

The welding is pretty shithouse but I haven't welded for years and the grinding and polishing hides most of it. The buckle has a loop through which the belt connects and a single pin which selects the size. The end of the belt comes around out the front (or can go behind) and a loop holds it in place.

The front finish is a sort of coarse brushed/dented appearance from using an angle grinder, wire brush and polishing wheel. I'm still not sure on the finish but I will probably clear coat it.

The belt I got made up is 70mm wide and the loop which connects to the buckle uses press-studs so I can make more buckles and easily replace them. 70mm is about the widest that suits the kilts I have which is just as well because I didn't really know what it would look like till it was made.

Not particularly cheap either at $99 but at least it's locally made and very solid leather - it should last forever. My existing belt was relatively 'cheap' one from utkilts that uses velcro to adjust the length. But the finish is wearing already (mostly creases), the velcro is coming off around the back, and the buckle - while ok - is a bit cheap. The actual bits are made in Pakistan I believe but the shipping costs from USA are outrageous - although they seem to have gotten slightly better, but to get the same belt ($26) and buckle ($17) again would cost $77 when shipping is added anyway, and they don't handle GST (I have no idea whether this means you get hit with import hassles above the $7 GST cost). And that's the absolute cheapest/slowest option, it ranges up to $130!

Actually I have an idea for another buckle mechanism that I might try out when I get time, if I do that I might get a 60mm belt made. The other idea would be a lower profile, hide the tail of the belt (wrap under), and possible be hole-less if I can create a binding mechanism that wont damage the front surface of the belt.

And today I turned one of the practice pieces of barrel strap into a bottle opener. I drilled some holes and filed out the opening shape by hand.

The finish is a little shit because I cut a bit deep using a sanding disc on an angle grinder and gave up trying to sand it out, although it is a lot shinier than it appears in the photo.

Partly I was experimenting with finishes and patterns and i'm happier with the pattern here, or at least the general approach. I created a round ended punch from an old broken screwdriver and used a small portable jackhammer (/ hammer drill) to pound in the dots. Because i'm just cold working it's a bit difficult to do much in the pattern department.

Gets me away from the computer screen anyway, i'm kinda burnt out on that. I'm not really doing enough hours lately for the guy who pays me (for various reasons beyond our control he's got more money than hours I want to work!), although the customers who pay him are quite happy with the output!

I'm at the point where I finally need to get some glasses. I had another eye test last week and while I can still survive without it it's to the point that i'm not recognising people from afar and squinting a bit too much reading at times. I need a separate reading and distance script unfortunately so I got a pair of sunnies for distance and reading glasses for work. They would've helped with the fabrication above! It's going to take a while to get used to them, and/or work out whether I get progressive lenses or whatnot, for example I can't read games very well on my TV, but that's farther away than the reading glasses work at, sigh. I guess i'll find out in a week or so.

Tagged workshop.
Sunday, 04 November 2018, 20:31

Pulling things apart

I pulled an old deskjet printer apart the other day. It wasn't a particularly expensive machine and it broke years ago; it's just been sitting in the corner of my room collecting dust for the day I threw it out or took out the useful bits. I guess what I found most interesting is despite it being a disposable item just how well put together it was.

Basically it looks like it was designed to be repairable. Can't imagine the equivalent today would be.

Flymo

I also have a more recent machine that still runs, a mains powered electric hover mower. It's one that has the motor on a separate spindle to the blade which is driven by a belt. For a few years it's been 'running' rough due to bung bearings, I had looked at it before but it looked irrepearable. The whole base-plate, clutch and drive pulley assembly can be bought as a FRU but it must be ordered from England. The last time I tried I couldn't get the payment to go through and so i've just been living with a mower on the edge of self-destruction.

Today it was getting so bad I finally had another look at it. And lo! I managed to get the bearings out, although it took about 2+ hours with the tools I have at hand and an awful lot of swearing! Anyway the two bearings should be easy to source and hopefully it'll be back up and running once I put it back together. It would be a pity to get a whole new mower just because a couple of small cheap parts failed, and repairing it would've been prohibitively expensive. Hate wasting stuff.

Apart from all that I took a few days off and have been doing a lot of gardening, preparing vegetable gardens and whatnot. Hopefully a year or so basically fallow will work in my favour, I need some more exotic chillies and home-grown tomatoes can't be beat.

Tagged biographical, philosophy.
Wednesday, 24 October 2018, 12:33

Beer for the Win!

So apparently I won one of these things.

Just in time for summer!

I might have a beer to celebrate! I spent the morning pulling out weeds so I earned it!

Tagged biographical.
Tuesday, 23 October 2018, 18:47

Fast incremental Java builds with openjdk 11 and GNU make

This post wont match the article but I think i've solved all the main problems needed to make it work. The only thing missing is ancestor scanning - which isn't trivial but should be straightforward.

Conceptually it's quite simple and it doesn't take much code but bloody hell it took a lot of mucking about with make and the javac TaskListener.

I took the approach I outlined yesterday, I did try to get more out of the AST but couldn't find the info I needed. The module system is making navigating source-code a pain in Netbeans (it wont find modules if the source can't). Some of the 'easy' steps turned out to be a complete headfuck. Anyway some points of interest.

Dependency Tracking

Even though a java file can create any number of classes one doesn't need to track any of the non top-level .class files that might be created for dependency purposes. Any time a .java file is compiled all of it's generated classes are created at the same time. So if any java file uses for example a nested class it only need to track the source file.

I didn't realise this at first and it got messy fast.

Modified Class List

I'm using a javac plugin (-Xplugin) to track the compilation via a TaskListener. This notifies the plugin of various compilation stages including generating class files. The painful bit here is that you don't get information on the actual class files generated, only on the source file and the name of the class being generated. And you can't get the actual name of the class file for anonymous inner classes (it's in the implementation but hidden from public view). In short it's a bit messy getting a simple and complete list of every class file generated from every java file compiled.

But for various other reasons this isn't terribly important so I just track the toplevel class files; but it was a tedious discovery process on a very poorly documented api.

When the compiler plugin get the COMPILATION finished event it uses the information it gathered (and more it discovers) to generate per-class dependency files similar to `gcc -MD'.

Dependency Generation & Consistency

To find all the (immediate) dependencies the .class file is processed. The ClassInfo records provide a starting point but all field and method signatures (descriptors) must be parsed as well.

When an inner class is encountered it's container class is used to determine if the inner class is still extant in the source code - if not it can be deleted.

And still this isn't quite enough - if you have a package private additional class embedded inside the .java file there is no cross-reference between the two apart from the SourceFile attribute and implied package path. So to determine if this is stale one needs to check the Modified Class List instead.

The upshot is that you can't just parse the modified class list and any inner classes that reference them. I scan a whole package at a time and then look for anomilies.

One-shot compile

Because invoking the compiler is slow - but also because it will discover and compile classes as necessary - it's highly beneficial to run it once only. Unfortunately this is not how make works and so it needs to be manipulated somewhat. After a few false starts I found a simple way that works:

The per-module rules are required due to the source-tree naming conventions used by netbeans (src/[module]/classes/[name] to build/modules/[module]/[name]), a common-stem based approach is also possible in which case it wouldn't be required. In practice it isn't particularly onerous as I use metamake facilities to generate these per-module rules automatically.

I spent an inordinate amount of time trying to get this to work but kept hitting puzzling (but documented) behaviour with pattern and implicit rule chaining and various other issues. One big one was using concrete rules (made files) for tracking stages, suddenly everything breaks.

I resorted to just individual java invocations as one would do for gcc, and trying the compiler server idea to mitigate the costs. It worked well enough particularly since it parallelises properly. But after I went to bed I realised i'd fucked up and then spent a few hours working out a better solution.

Example

This is the prototype i've been using to develop the idea.

modules:=notzed.proto notzed.build

SRCS:=$(shell find src -name '*.java')
CLASSES:=$(foreach mod,$(modules),\
 $(patsubst src/$(mod)/classes/%.java,classes/$(mod)/%.class,$(filter src/$(mod)/%,$(SRCS))))

all: $(CLASSES)
        lists='$(foreach mod,$(modules),$(wildcard status/$(mod).list))' ; \
        built='$(patsubst %.list,%.built,$(foreach mod,$(modules),$(wildcard status/$(mod).list)))' ; \
        files='$(addprefix @,$(foreach mod,$(modules),$(wildcard status/$(mod).list)))' ; \
        if [ -n "$$built" ] ; then \
                javac -Xplugin:javadepend --processor-module-path classes --module-source-path 'src/*/classes' -d classes $$files ; \
                touch $$built; \
                rm $$lists ; \
        else \
                echo "All classes up to date" ; \
        fi

define makemod=
classes/$1/%.class: src/$1/classes/%.java
        $$(file >> status/$1.list,$$<)

$1: $2
        if [ -f status/$1.list ] ; then \
                javac --module-source-path 'src/*/classes' -d classes @status/$1.list ; \
                rm status/$1.list ; \
                touch status/$1.built ; \
        fi
endef

$(foreach mod,$(modules),$(eval $(call makemod,$(mod),\
  $(patsubst src/$(mod)/classes/%.java,classes/$(mod)/%.class,$(filter src/$(mod)/%,$(SRCS))))))

-include $(patsubst classes/%,status/%.d,$(CLASSES))

In addition there is a compiler plugin which is about 500 lines of standalone java code. This creates the dependency files (included at the end above) and purges any stale .class files.

I still need to work out a few details with ancestor dependencies and a few other things.

Tagged java.
Monday, 22 October 2018, 17:42

Java 11 Modules, Building

I'm basically done modularising the code at work - at least the active code. I rather indulgently took the opportunity to do a massive cleanup - pretty well all the FIXMEs, should be FIXMEs, TODOs, dead-code and de-duplication that's collected over the last few years. Even quite a few 'would be a bit nicers'. It's not perfect but it was nice to be able to afford the time to do it.

I'm still trying to decide if I break the projects up into related super-projects or just put everything in the single one as modules. I'm aiming toward the latter because basically i'm sick of typing "cd ../blah" so often, and Netbeans doesn't recompile the dependencies properly.

I'm going to reset the repository and try using git. I don't like it but I don't much like mercurial either.

Building

At the moment I have a build system which uses make and compiles at the module level - i.e. any source changes and the whole module is recompiled, and one can add explicit module-module dependencies to control the build order and ensure a consistent build.

One reason I do this is because there is no 1:1 correspondance between build sources and build classes. If you add or remove nested or anonymous (or co-located) classes from a source file that adds or removes .class files which are generated. So to ensure there are no stale classes I just reset it on every build.

This isn't too bad and absolutely guarantees a consistent build (assuming one configures the inter-module dependencies properly) but the compiler is still invoked multiple times which has overheads.

Building Faster

Really the speed isn't a problem for these projects but out of interest i'm having a look at a couple of other things.

One is relatively simple - basically use JSR-199 to create a compiler server something like the jdk uses to build itself.

The more complicated task is incremental builds using GNU Make. I think I should be able to hook into JavacTask and with a small bit of extra code create something akin to the "gcc -MD" option for auto-generating dependencies. It has the added complication of having to detect and remove stale .class files, and doing it all in a way that make understands. I've already done a few little experiments today while I was procrastinating over some weeding.

Using JavacTask it is possible to find out all the .class files that are generated for a given source file. This is one big part of the puzzle and covers the first-level dependencies (i.e. %.java: %.class plus all the co-resident classes). One can also get the AST and other information but that isn't necessary here.

To find the other dependencies I wrote a simple class file decoder which finds all the classes referenced by the binary. Some relatively simple pattern matching and name resolution should be able to turn this into a dependency list.

Actually it may not be necessary to use JavacTask for this because the .class files contain enough information. There is extra overhead because they must be parsed, but they are simple to parse.

Tagged java.
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