Amiga on Fire on Playstore

The latest thing to try. A Cleanto Amiga Forever OS 3.1 install to SD card in the Amazon Fire 7. Is it the way to get a low power portable development system? Put an OS on an SD and save main memory? An efficient OS from times of sub 20 MHz, and 50 MB hard drives.

Is it relevant in the PC age? Yes. All the source code in Pascal or C can be shuffled to PC, and I might even develop some binary prototype apps. Maybe a simple web engine is a good thing to develop. With the low CSS bull and AROS open development for x86 architecture becoming better at making for a good VM sandbox experience with main browsing on a sub flavour of bloat OS 2020. A browser, a router and an Amiga.

Uae4arm is the emulation app available from the Playstore. I’m looking forward to some Aminet greatness. Some mildly irritated coding in free Pascal with objects these days, and a full GCC build chain. Even a licenced set of games will shrink the Android entertainment bloat. A bargain rush for the technical. Don’t worry you ST users, it’s a chance to dream.

Lazarus lives. Or at least Borglaz the great is as it was. Don’t expect to be developing video realtime code or supercomputer forecasts. I hear there is even a python. I wonder if there is some other nice things. GCC and a little GUI redo? It’s not about making replacements for Android apps, more a less bloat but a full do OS with enough test and utility grunt to make. I wonder how pas2js is. There is also AMOS 2.0 to turn AMOS source into nice web apps. It’s not as silly as it seems.

Retro minimalism is more power in the hands of code designers. A bit of flange and boilerplate later and it’s a consumer product option with some character.

So it needs about a 100 MB hard disk file located not on the SD as it needs write access, and some changes of disk later and a boot of a clean install is done. Add the downloads folder as a disk and alter the mouse speed for the plugged in OTG keyboard. Excellent. I’ve got more space and speed than I did in the early 90s and 128 MB of Zorro RAM. Still an AGA A1200 but with a 68040 on its fastest setting.

I’ve a plan to install free Pascal and GCC along with some other tools to take the ultra portable Amiga on the move. The night light on the little keyboard will be good for midnight use. Having a media player in the background will be fun and browser downloads should be easy to load.

I’ve installed total commander on the Android side to help with moving files about. The installed BSD socket library would allow running an old Mosaic browser, or AWeb but both are not really suited to any dynamic content. They would be fast though. In practice Chrome and a download mount is more realistic. It’s time to go Aminet fishing.

It turns out that is is possible to put hard files on the SD card, but they must be placed in the Android app data directory and made by the app for correct permissions. So a 512 MB disk was made for better use of larger development versions. This is good for the Pascal 3.1.1 version.

Onwards to install a good editor such as Black’s Editor and of course LHA and some other goodies such as NewIcons. I’ll delete the LCL alpha units from Pascal as these will not be used by me. I might even get into ARexx or some of the wonderfull things on those CD images from Meeting Pearls or a cover disk archive.

Update: For some reason the SD card hard disk image becomes read locked. The insistent gremlins of the demands of time value money. So it’s 100 MB and a few libraries short of C. Meanwhile Java N-IDE is churning out class files, PipedInputStream has the buffer to stop PipedOutputStream waffling on, filling up memory. Hecl the language is to be hooked into the CLI I’m throwing together. Then some data time streams and some algorithms. I think the interesting bit today was the idea of stream variables. No strings, a minimum would be a stream.

So after building a CLI and adding in some nice commands, maybe even JOGL as the Android graphics? You know the 32 and 64 bit restrictions (both) on the play store though. I wonder if both are pre-built as much of the regular Android development cycle is filled with crap. Flutter looks good, but for mobile CLI tools with some style of bitmap 80’s, it’s just a little too formulaic.

Today’s Thought


import 'dart:math';

class PseudoRandom {
  int a;
  int c;
  int m = 1 << 32;
  int s;
  int i;

  PseudoRandom([int prod = 1664525, int add = 1013904223]) {
    a = prod;
    c = add;
    s = Random().nextInt(m) * 2 + 1;//odd
    next();// a fast round
    i = a.modInverse(m);//4276115653 as inverse of 1664525
  }

  int next() {
    return s = (a * s + c) % m;
  }

  int prev() {
    return s = (s - c) * i % m;
  }
}

class RingNick {
  List<double> walls = [ 0.25, 0.5, 0.75 ];
  int position = 0;
  int mostEscaped = 1;//the lowest pair of walls 0.25 and 0.5
  int leastEscaped = 2;//the highest walls 0.5 and 0.75
  int theThird = 0;//the 0.75 and 0.25 walls
  bool right = true;
  PseudoRandom pr = PseudoRandom();

  int _getPosition() => position;

  int _asMod(int pos) {
    return pos % walls.length;
  }

  void _setPosition(int pos) {
    position = _asMod(pos);
  }

  void _next() {
    int direction = right ? 0 : walls.length - 1;//truncate to 2
    double wall = walls[_asMod(_getPosition() + direction)];
    if(pr.next() > (wall * pr.m).toInt()) {
      //jumped
      _setPosition(position + (right ? 1 : walls.length - 1));
    } else {
      //not jumped
      right = !right;//bounce
    }
  }

  void _prev() {
    int direction = !right ? 0 : walls.length - 1;//truncate to 2
    double wall = walls[_asMod(_getPosition() + direction)];
    if(pr.s > (wall * pr.m).toInt()) {// the jump over before sync
      //jumped
      _setPosition(position + (!right ? 1 : walls.length - 1));
    } else {
      //not jumped
      right = !right;//bounce -- double bounce and scale before sync
    }
    pr.prev();//exact inverse
  }

  void next() {
    _next();
    while(_getPosition() == mostEscaped) _next();
  }

  void prev() {
    _prev();
    while(_getPosition() == mostEscaped) _prev();
  }
}

class GroupHandler {
  List<RingNick> rn;

  GroupHandler(int size) {
    if(size % 2 == 0) size++;
    rn = List<RingNick>(size);
  }

  void next() {
    for(RingNick r in rn) r.next();
  }

  void prev() {
    for(RingNick r in rn.reversed) r.prev();
  }

  bool majority() {
    int count = 0;
    for(RingNick r in rn) if(r._getPosition() == r.leastEscaped) count++;//a main cumulative
    return (2 * count > rn.length);// the > 2/3rd state is true
  }

  void modulate() {
    for(RingNick r in rn) if(r._getPosition() == r.leastEscaped) {
      r._setPosition(r.theThird);
    } else {
      //mostEscaped eliminated by not being used
      r._setPosition(r.leastEscaped);
    }
  }
}

class Modulator {
  GroupHandler gh = GroupHandler(55);

  int putBit(bool bitToAbsorb) {//returns absorption status
    gh.next();
    if(gh.majority()) {//main zero state
      if(bitToAbsorb) {
        gh.modulate();
        return 0;//a zero yet to absorb
      } else {
        return 1;//absorbed zero
      }
    } else {
      return -1;//no absorption emitted 1
    }
  }

  int getBit(bool bitLastEmitted) {
    if(gh.majority()) {//zero
      gh.prev();
      return 1;//last bit not needed emit zero
    } else {
      if(bitLastEmitted) {
        gh.prev();
        return -1;//last bit needed and nothing to emit
      } else {
        gh.modulate();
        gh.prev();
        return 0;//last bit needed, emit 1
      }
    }
  }
}

class StackHandler {
  List<bool> data = [];
  Modulator m = Modulator();

  int putBits() {
    int count = 0;
    while(data.length > 0) {
      bool v = data.removeLast();
      switch(m.putBit(v)) {
        case -1:
          data.add(v);
          data.add(true);
          break;
        case 0:
          data.add(false);
          break;
        case 1:
          break;//absorbed zero
        default: break;
      }
      count++;
    }
    return count;
  }

  void getBits(int count) {
    while(count > 0) {
      bool v;
      v = (data.length == 0 ? false : data.removeLast());//zeros out
      switch(m.getBit(v)) {
        case 1:
          data.add(v);//not needed
          data.add(false);//emitted zero
          break;
        case 0:
          data.add(true);//emitted 1 used zero
          break;
        case -1:
          break;//bad skip, ...
        default: break;
      }
      count--;
    }
  }
}

Statistics and Damn Lies

I was wondering over the statistics problem I call the ABC problem. Say you have 3 walls in a circular path, of different heights, and between them are points marked A, B and C. If in any ‘turn’ the ‘climber’ attempts to scale the wall in the current clockwise or anti-clockwise direction. The chances of success are proportional to the wall height. If the climber fails to get over a wall, they reverse direction. A simple thing, but what are the chances of the climber will be found facing clockwise just before scaling or not a wall? Is it close to 0.5 as the problem is not symmetric?

More interestingly the climber will be in a very real sense captured more often in the cell with the highest pair of walls. If the cell with the lowest pair of walls is just considered as consumption of time, then what is the ratio of the containment time over the total time not in the least inescapable wall cell?

So the binomial distribution of the elimination of the ’emptiest’ when repeating this pattern as an array with co-prime ‘dice’ (if all occupancy has to be in either of the most secure cells in each ‘ring nick’), the rate depends on the number of ring nicks. The considered security majority state is the state (selected from the two most secure cell states) which more of the ring nicks are in, given none are in the least secure state of the three states.

For the ring nick array to be majority most secure more than two thirds the time is another binomial or two away. If there are more than two-thirds of the time (excluding gaping minimal occupancy cells) the most secure state majority and less than two-thirds (by unitary summation) of the middle-security cells in majority, there exists a Jaxon Modulation coding to place data on the Prisoners by reversing all their directions at once where necessary, to invert the majority into a minority rarer state with more Shannon information. Note that the pseudo-random dice and other quantifying information remains constant in bits.

Dedicated to Kurt Godel … I am number 6. 😀

BLZW Compression Java

Uses Sais.java with dictionary persist, and initialisation corrections. Also with alignment fix and unused function removed. A 32 bucket context provides an effective 17 bit dictionary key, using just 12 bits, along with the BWT redundancy model. This should provide superior compression of text. Now includes the faster skip decode. Feel free to donate to grow some open source based on data compression and related codecs.





/* BWT/LZW fast wide dictionary. (C)2016-2017 K Ring Technologies Ltd.
The context is used to make 32 dictionary spaces for 128k symbols max.
This then givez 12 bit tokens for an almost effective 16 bit dictionary.
For an approximate 20% data saving above regular LZW.

The process is optimized for L2 cache sizea.

A mod 16 gives DT and EU collisions on hash.
A mod 32 is ASCII proof, and hence good for text.

The count compaction includes a skip code for efficient storage.
The dictionary persists over the stream for good running compression.
64k blocks are used for fast BWT. Larger blocks would give better
compression, but be slower. The main loss is the count compactio storage.

An arithmetic coder post may be effective but would be slow. Dictonary
acceleration would not necessarily be useful, and problematic after the
stream start. A 12 bit code is easy to pack, keeps the dictionary small
and has the sweet spot of redundancy in while not making large rare or
single use symbols.
*/

package uk.co.kring.net;

import java.io.EOFException;
import java.io.Externalizable;
import java.io.FilterInputStream;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.HashMap;

/**
 * Created by user on 06/06/2016.
 */
public class Packer {

    public static class OutputStream extends FilterOutputStream implements Externalizable {

        byte[] buf = new byte[4096 * 16];//64K block max
        int cnt = 0;//pointer to end
        int[] dmax = new int[32];
        HashMap<String, Integer> dict;

        public OutputStream(java.io.OutputStream out) {
            super(out);
        }

        @Override
        public void readExternal(ObjectInput input) throws IOException, ClassNotFoundException {
            out = (java.io.OutputStream)input.readObject();
            input.read(buf);
            cnt = input.readChar();
            dict = (HashMap<String, Integer>)input.readObject();
        }

        @Override
        public void writeExternal(ObjectOutput output) throws IOException {
            output.writeObject(out);
            output.write(buf);
            output.writeChar(cnt);
            output.writeObject(dict);
        }

        @Override
        public void close() throws IOException {
            flush();
            out.close();
        }

        private byte pair = 0;
        private boolean two = false;

        private void outputCount(int num, boolean small, boolean tiny) throws IOException {
            if(tiny) {
                out.write((byte)num);
                return;
            }
            if(small) {
                out.write((byte)num);
                pair = (byte)((pair << 4) + (num >> 8));
                if(two) {
                    two = false;
                    out.write(pair);
                } else {
                    two = true;
                }
                return;
            }
            out.write((byte)(num >> 8));
            out.write((byte)num);
        }

        @Override
        public void flush() throws IOException {
            outputCount(cnt, false, false);//just in case length
            char[] count = new char[256];
            if(dict == null) {
                dict = new HashMap<>();
                for(int i = 0; i < 32; i++) {
                    dmax[i] = 256;//dictionary max
                }
            }
            for(int i = 0; i < cnt; i++) {
                count[buf[i]]++;
            }
            char skip = 0;
            boolean first = true;
            char acc = 0;
            char[] start = new char[256];
            for(int j = 0; j < 2; j++) {
                for (int i = 0; i < 256; i++) {
                    if(j == 0) {
                        acc += count[i];
                        start[i] = acc;
                    }
                    if (count[i] == 0) {
                        skip++;
                        if (first) {
                            outputCount(0, false, true);
                            first = false;
                        }
                    } else {
                        if (skip != 0) {
                            outputCount(skip, false, true);
                            skip = 0;
                            first = true;
                        }
                        outputCount(count[i], false, true);
                        count[i] >>= 8;
                    }
                }
                if(skip != 0) outputCount(skip, false, true);//final skip
            }
            int[] ptr = new int[buf.length];
            byte[] bwt = new byte[buf.length];

            outputCount(Sais.bwtransform(buf, bwt, ptr, cnt), false, false);

            //now an lzw
            String sym = "";
            char context = 0;
            char lastContext = 0;
            int test = 0;
            for(int j = 0; j < cnt; j++) {
                while(j >= start[context]) context++;
                if(lastContext == context) {
                    sym += bwt[j];//add a char
                } else {
                    lastContext = context;
                    outputCount(test, true, false);
                    sym = "" + bwt[j];//new char
                }
                if(sym.length() == 1) {
                    test = (int)sym.charAt(0);
                } else {
                    if(dict.containsKey(context + sym)) {
                        test = dict.get(context + sym);
                    } else {
                        outputCount(test, true, false);
                        if (dmax[context & 0x1f] < 0x1000) {//context limit
                            dict.put(context + sym, dmax[context & 0x1f]);
                            dmax[context & 0x1f]++;
                        }
                        sym = "" + bwt[j];//new symbol
                    }
                }
            }
            outputCount(test, true, false);//last match
            if(!two) outputCount(0, true, false);//aligned data
            out.flush();
            cnt = 0;//fill next buffer
        }

        @Override
        public void write(int oneByte) throws IOException {
            if(cnt == buf.length) flush();
            buf[cnt++] = (byte)oneByte;
        }
    }

    public static class InputStream extends FilterInputStream implements Externalizable {

        @Override
        public void readExternal(ObjectInput input) throws IOException, ClassNotFoundException {
            in = (java.io.InputStream)input.readObject();
            input.read(buf);
            idx = input.readChar();
            cnt = input.readChar();
            dict = (HashMap<Integer, String>)input.readObject();
        }

        @Override
        public void writeExternal(ObjectOutput output) throws IOException {
            output.writeObject(in);
            output.write(buf);
            output.writeChar(idx);
            output.writeChar(cnt);
            output.writeObject(dict);
        }

        //SEE MIT LICENCE OF Sais.java

        private static void unbwt(byte[] T, byte[] U, int[] LF, int n, int pidx) {
            int[] C = new int[256];
            int i, t;
            //for(i = 0; i < 256; ++i) { C[i] = 0; }//Java
            for(i = 0; i < n; ++i) { LF[i] = C[(int)(T[i] & 0xff)]++; }
            for(i = 0, t = 0; i < 256; ++i) { t += C[i]; C[i] = t - C[i]; }
            for(i = n - 1, t = 0; 0 <= i; --i) {
                t = LF[t] + C[(int)((U[i] = T[t]) & 0xff)];
                t += (t < pidx) ? 1 : 0;
            }
        }

        byte[] buf = new byte[4096 * 16];//64K block max
        int cnt = 0;//pointer to end
        int idx = 0;
        int[] dmax = new int[32];
        HashMap<Integer, String> dict;

        private boolean two = false;
        private int vala = 0;
        private int valb = 0;

        private int reader() throws IOException {
            int i = in.read();
            if(i == -1) throw new EOFException("End Of Stream");
            return i;
        }

        private char inCount(boolean small, boolean tiny) throws IOException {
            if(tiny) return (char)reader();
            if(small) {
                if(!two) {
                    vala = reader();
                    valb = reader();
                    int valc = reader();
                    vala += (valc << 4) & 0xf00;
                    valb += (valc << 8) & 0xf00;
                    two = true;
                } else {
                    vala = valb;
                    two = false;
                }
                return (char)vala;
            }
            int val = reader() << 8;
            val += reader();
            return (char)val;
        }

        public InputStream(java.io.InputStream in) {
            super(in);
        }

        @Override
        public int available() throws IOException {
            return cnt - idx;
        }

        @Override
        public void close() throws IOException {
            in.close();
        }

        private void doReads() throws IOException {
            if(available() == 0) {
                two = false;//align
                if(dict == null) {
                    dict = new HashMap<>();
                    for(int i = 0; i < 32; i++) {
                        dmax[i] = 256;
                    }
                }
                cnt = inCount(false, false);
                char[] count = new char[256];
                char tmp;
                for(int j = 0; j < 2; j++) {
                    for (int i = 0; i < 256; i++) {
                        count[i] += tmp = (char)(inCount(false, true) << (j == 1?8:0));
                        if (tmp == 0) {
                            i += inCount(false, true) - 1;
                        }
                    }
                }
                for(int i = 1; i < 256; i++) {
                    count[i] += count[i - 1];//accumulate
                }
                if(cnt != count[255]) throw new IOException("Bad Input Check (character count)");
                int choose = inCount(false, false);//read index
                if(cnt < choose) throw new IOException("Bad Input Check (selected row)");
                byte[] build;//make this
                //then lzw
                //rosetta code
                int context = 0;
                int lastContext = 0;
                String w = "" + inCount(true, false);
                StringBuilder result = new StringBuilder(w);
                while (result.length() < cnt) {//not yet complete
                    char k = inCount(true, false);
                    String entry;
                    while(result.length() > count[context]) {
                        context++;//do first
                        if (context > 255)
                            throw new IOException("Bad Input Check (character count)");
                    }
                    if(k < 256)
                        entry = "" + k;
                    else if (dict.containsKey(((context & 0x1f) << 16) + k))
                        entry = dict.get(((context & 0x1f) << 16) + k);
                    else if (k == dmax[context & 0x1f])
                        entry = w + w.charAt(0);
                    else
                        throw new IOException("Bad Input Check (token: " + k + ")");
                    result.append(entry);
                    // Add w+entry[0] to the dictionary.
                    if(lastContext == context) {
                        if (dmax[context & 0x1f] < 0x1000) {
                            dict.put(((context & 0x1f) << 16) +
                                    (dmax[context & 0x1f]++),
                                    w + entry.charAt(0));
                        }
                        w = entry;
                    } else {
                        //context change
                        context = lastContext;
                        //and following context should be a <256 ...
                        if(result.length() < cnt) {
                            w = "" + inCount(true, false);
                            result.append(w);
                        }
                    }
                }
                build = result.toString().getBytes();
                //working buffers
                int[] wrk = new int[buf.length];
                unbwt(build, buf, wrk, buf.length, choose);
                idx = 0;//ready for reads
                if(!two) inCount(true, false);//aligned data
            }
        }

        @Override
        public int read() throws IOException {
            try {
                doReads();
                int x = buf[idx++];
                doReads();//to prevent avail = 0 never access
                return x;
            } catch(EOFException e) {
                return -1;
            }
        }

        @Override
        public long skip(long byteCount) throws IOException {
            long i;
            for(i = 0; i < byteCount; i++)
                if(read() == -1) break;
            return i;
        }

        @Override
        public boolean markSupported() {
            return false;
        }

        @Override
        public synchronized void reset() throws IOException {
            throw new IOException("Mark Not Supported");
        }
    }
}