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Emesary : rework transfer encoding

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This better supports -ve numbers by using -range/2 to range/2 instead of prepending a '-' to the start of the encoded value for -ve numbers.
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Richard Harrison 2020-06-05 12:46:54 +02:00
parent d006f00cd4
commit 077d44f347
1 changed files with 54 additions and 59 deletions
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113
Nasal/emesary.nas
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@ -20,7 +20,7 @@
#
# Version : 4.8
#
# Copyright © 2016 Richard Harrison Released under GPL V2
# Copyright © 2016 Richard Harrison Released under GPL V2
#
#---------------------------------------------------------------------------*/
@ -296,13 +296,12 @@ var Recipient =
# use this transmitters, however other transmitters can be created and merely use the global transmitter to discover each other
var GlobalTransmitter = Transmitter.new("GlobalTransmitter");
#
#
# This is basically a base64 like encode except we just use alphanumerics which gives us a base62 encode.
# Base method of transferring all numeric based values.
# Using the same techinque as base64 - except this is base248 because we can use a much wider range of characters.
#
var BinaryAsciiTransfer =
{
# alphabet : "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ",
alphabet : chr(1)~chr(2)~chr(3)~chr(4)~chr(5)~chr(6)~chr(7)~chr(8)~chr(9)~chr(10)~chr(11)~chr(12)~chr(13)
~chr(14)~chr(15)~chr(16)~chr(17)~chr(18)~chr(19)~chr(20)~chr(21)~chr(22)~chr(23)~chr(24)~chr(25)
~chr(26)~chr(27)~chr(28)~chr(29)~chr(30)~chr(31)~chr(34)
@ -319,46 +318,48 @@ var BinaryAsciiTransfer =
~chr(227)~chr(228)~chr(229)~chr(230)~chr(231)~chr(232)~chr(233)~chr(234)~chr(235)~chr(236)~chr(237)
~chr(238)~chr(239)~chr(240)~chr(241)~chr(242)~chr(243)~chr(244)~chr(245)~chr(246)~chr(247)~chr(248)
~chr(249)~chr(250)~chr(251)~chr(252)~chr(253)~chr(254)~chr(255),
# base248: powers of 2 (i.e. po2(x) = f(248 ^ x);
# 0 based list so the first item is really[1]; i.e. 124 which is 248/2 as po2 is the magnitude excluding sign
po2: [1, 124, 30752, 7626496, 1891371008, 469060009984, 116326882476032, 28849066854055936],
_base: 248,
spaces: " ",
empty_encoding: chr(1)~chr(1)~chr(1)~chr(1)~chr(1)~chr(1)~chr(1)~chr(1)~chr(1)~chr(1)~chr(1),
encodeInt : func(num,length)
encodeNumeric : func(_num,length,factor)
{
#print(BinaryAsciiTransfer.po2[1]);
var irange = int(BinaryAsciiTransfer.po2[length] / factor);
var scale = int(irange / factor);
#print("EC ",irange, " sc=",scale);
var num = int(_num / factor);
if (num < -scale) num = -scale;
else if (num > scale) num = scale;
num = int(num + irange);
if (num == 0)
return substr(BinaryAsciiTransfer.empty_encoding,0,length);
var arr="";
var negate=0;
if (num < 0) {
negate = 1;
num = -num;
}
while (num > 0 and length > 0) {
var num0 = num;
num = (int)(num / BinaryAsciiTransfer._base);
num = int(num / BinaryAsciiTransfer._base);
rem = num0-(num*BinaryAsciiTransfer._base);
arr =substr(BinaryAsciiTransfer.alphabet, rem,1) ~ arr;
length -= 1;
}
if (length>0)
arr = substr(BinaryAsciiTransfer.spaces,0,length)~arr;
if(negate)
arr = "-"~arr;
return arr;
},
retval : {value:0, pos:0},
decodeInt : func(str, length, pos)
decodeNumeric : func(str, length, factor, pos)
{
var power = length-1;
var negate = 0;
var irange = int(BinaryAsciiTransfer.po2[length]/factor);
var power = length - 1;
BinaryAsciiTransfer.retval.value = 0;
BinaryAsciiTransfer.retval.pos = pos;
if (substr(str,BinaryAsciiTransfer.retval.pos,1)=="-") {
negate=1;
BinaryAsciiTransfer.retval.pos = BinaryAsciiTransfer.retval.pos+1;
}
while (length > 0 and power > 0) {
var c = substr(str,BinaryAsciiTransfer.retval.pos,1);
if (c != " ") break;
@ -373,7 +374,7 @@ var BinaryAsciiTransfer =
var cc = find(c,BinaryAsciiTransfer.alphabet);
if (cc < 0)
{
print("Emesary: BinaryAsciiTransfer.decodeInt: Bad encoding ");
print("Emesary: BinaryAsciiTransfer.decodeNumeric: Bad encoding ");
return BinaryAsciiTransfer.retval;
}
BinaryAsciiTransfer.retval.value += int(cc * math.exp(math.ln(BinaryAsciiTransfer._base) * power));
@ -382,9 +383,15 @@ var BinaryAsciiTransfer =
length = length-1;
BinaryAsciiTransfer.retval.pos = BinaryAsciiTransfer.retval.pos + 1;
}
if (negate)
BinaryAsciiTransfer.retval.value = -BinaryAsciiTransfer.retval.value;
BinaryAsciiTransfer.retval.value -= irange;
BinaryAsciiTransfer.retval.value = BinaryAsciiTransfer.retval.value * factor;
return BinaryAsciiTransfer.retval;
},
encodeInt : func(num,length){
return me.encodeNumeric(num, length, 1.0);
},
decodeInt : func(str, length, pos){
return me.decodeNumeric(str, length, 1.0, pos);
}
};
@ -417,15 +424,18 @@ var TransferString =
actual_len = actual_len + 1;
}
}
rv = BinaryAsciiTransfer.encodeInt(l,1) ~ rv;
rv = BinaryAsciiTransfer.encodeNumeric(l,1,1.0) ~ rv;
return rv;
},
decode : func(v,pos)
{
var dv = BinaryAsciiTransfer.decodeInt(v,1,pos);
var dv = BinaryAsciiTransfer.decodeNumeric(v,1,1.0,pos);
var length = dv.value;
if (length == 0)
if (length == 0){
dv.value = "";
return dv;
}
var rv = substr(v,dv.pos,length);
dv.pos = dv.pos + length;
dv.value = rv;
@ -439,53 +449,38 @@ var TransferInt =
{
encode : func(v, length)
{
return BinaryAsciiTransfer.encodeInt(v,length);
return BinaryAsciiTransfer.encodeNumeric(v,length, 1.0);
},
decode : func(v, length, pos)
{
return BinaryAsciiTransfer.decodeInt(v,length,pos);
return BinaryAsciiTransfer.decodeNumeric(v,length, 1.0, pos);
}
};
var TransferFixedDouble =
{
po2: [1.0,124.0,30752.0,7626496.0,1891371008.0,469060009984.0,116326882476032.0,28849066854055936.0], # needs to match powers of BinaryAsciiTransfer._base
encode : func(v, length, factor)
{
var scale = int(me.po2[length] / factor);
var v = int(v * factor);
if (v < -scale) v = -scale;
else if (v > scale) v = scale;
return BinaryAsciiTransfer.encodeInt(int(v), length);
return BinaryAsciiTransfer.encodeNumeric(int(v), length, factor);
},
decode : func(v, length, factor, pos)
{
var scale = int(me.po2[length] / factor);
var dv = BinaryAsciiTransfer.decodeInt(v, length, pos);
dv.value = (int(dv.value)/factor);
return dv;
return BinaryAsciiTransfer.decodeNumeric(v, length, pos, factor);
}
};
var TransferNorm =
{
powers: [1,10.0, 100.0, 1000.0, 10000.0, 100000.0, 1000000.0, 10000000.0, 100000000.0, 1000000000.0, 10000000000.0, 100000000000.0],
po2: [1.0,123.0,30751.0,7626495.0,1891371007,469060009983,116326882476031,28849066854055935], # needs to match powers of BinaryAsciiTransfer._base
encode : func(v, length)
{
v = v + 1;
if(v>2)
v=2;
else if (v < 0)
v=0;
return BinaryAsciiTransfer.encodeInt(int(v * me.po2[length]),length);
return BinaryAsciiTransfer.encodeNumeric(int(v * BinaryAsciiTransfer.po2[length]),length, 1.0);
},
decode : func(v, length, pos)
{
dv = BinaryAsciiTransfer.decodeInt(v, length,pos);
dv.value = (dv.value/me.po2[length]) - 1;
dv = BinaryAsciiTransfer.decodeNumeric(v, length, 1.0, pos);
dv.value = (dv.value/BinaryAsciiTransfer.po2[length]);
return dv;
}
};
@ -494,11 +489,11 @@ var TransferByte =
{
encode : func(v)
{
return BinaryAsciiTransfer.encodeInt(v,1);
return BinaryAsciiTransfer.encodeNumeric(v,1, 1.0);
},
decode : func(v, pos)
{
return BinaryAsciiTransfer.decodeInt(v, 1,pos);
return BinaryAsciiTransfer.decodeNumeric(v, 1, 1.0, pos);
}
};
@ -511,17 +506,17 @@ var TransferCoord =
# 1 degree = 110574 meters;
encode : func(v)
{
return BinaryAsciiTransfer.encodeInt((v.lat()+90)*745654,5)
~ BinaryAsciiTransfer.encodeInt((v.lon()+180)*745654,5)
~ TransferInt.encode(v.alt(), 3);
return BinaryAsciiTransfer.encodeNumeric((v.lat()+90)*745654,5, 1.0)
~ BinaryAsciiTransfer.encodeNumeric((v.lon()+180)*745654,5, 1.0)
~ TransferNumeric.encode(v.alt(), 3, 1.0);
},
decode : func(v,pos)
{
var dv = BinaryAsciiTransfer.decodeInt(v,5,pos);
var dv = BinaryAsciiTransfer.decodeNumeric(v,5, 1.0 ,pos);
var lat = (dv.value / 745654)-90;
dv = BinaryAsciiTransfer.decodeInt(v,5,dv.pos);
dv = BinaryAsciiTransfer.decodeNumeric(v,5, 1.0 ,dv.pos);
var lon = (dv.value / 745654)-180;
dv = TransferInt.decode(v, 3, dv.pos);
dv = TransferNumeric.decode(v, 3, 1.0 ,dv.pos);
var alt =dv.value;
dv.value = geo.Coord.new().set_latlon(lat, lon).set_alt(alt);
@ -533,4 +528,4 @@ var TransferCoord =
#print ("i ",i, " --> ", (TransferNorm.decode(TransferNorm.encode(i,2), 2,0)).value);
#debug.dump(TransferNorm.decode(TransferNorm.encode(-1,2), 2,0));
#debug.dump(TransferNorm.decode(TransferNorm.encode(0,2), 2,0));
#debug.dump(TransferNorm.decode(TransferNorm.encode(1,2), 2,0));
#debug.dump(TransferNorm.decode(TransferNorm.encode(1,2), 2,0));