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New encoding scheme for transfer over bridge that is slightly more efficient in most cases.

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This commit is contained in:
Richard Harrison 2016-04-16 15:13:33 +02:00
parent bb24cfaec5
commit db7ddba8ba
1 changed files with 70 additions and 17 deletions
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87
Nasal/emesary.nas
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@ -210,17 +210,71 @@ 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");
var TransferCoord =
#
#
# This is basically a base64 like encode except we just use alphanumerics which gives us a base62 encode.
var BinaryAsciiTransfer =
{
encode : func(v)
alphabet : "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ",
encodeInt : func(num)
{
return mp_broadcast.Binary.encodeCoord(v);
if (num == 0)
return substr(BinaryAsciiTransfer.alphabet,0,1);
var arr="";
var _base = size(BinaryAsciiTransfer.alphabet);
while(num > 0)
{
var rem = math.mod(num,_base);
num = int(num / _base);
arr =substr(BinaryAsciiTransfer.alphabet, rem,1) ~ arr;
}
return arr;
},
decode : func(v)
decodeInt : func(v)
{
return mp_broadcast.Binary.decodeCoord(v);
var _base = size(BinaryAsciiTransfer.alphabet);
var power = size(v) - 1;
var num = 0;
var idx = 0;
for(var idx=0; idx < size(v); idx += 1)
{
var c = substr(v,idx,1);
var cc = find(c,BinaryAsciiTransfer.alphabet);
if (cc < 0)
return nil;
num += int(cc * math.exp(math.ln(_base) * power));
power -= 1;
}
return num;
}
};
var TransferCoord =
{
# 28 bits = 268435456 (268 435 456)
# to transfer lat lon (360 degree range) 268435456/360=745654
# we could use different factors for lat lon due to the differing range, however
# this will be fine.
encode : func(v)
{
return BinaryAsciiTransfer.encodeInt( (v.lat()+90)*745654) ~ "." ~
BinaryAsciiTransfer.encodeInt((v.lon()+180)*745654) ~ "." ~
BinaryAsciiTransfer.encodeInt((v.alt()+1400)*100);
}
,
decode : func(v)
{
var parts = split(".", v);
var lat = (BinaryAsciiTransfer.decodeInt(parts[0]) / 745654)-90;
var lon = (BinaryAsciiTransfer.decodeInt(parts[1]) / 745654)-180;
var alt = (BinaryAsciiTransfer.decodeInt(parts[2]) / 100)-1400;
return geo.Coord.new().set_latlon(lat, lon).set_alt(alt);
}
};
var TransferString =
{
#
@ -237,7 +291,7 @@ var TransferString =
var l = size(v);
if (l > 16)
l = 16;
var rv = mp_broadcast.Binary.encodeByte(l);
var rv = BinaryAsciiTransfer.encodeInt(l);
print ("Encode string ",v," l=",l);
for(var ii = 0; ii < l; ii = ii + 1)
@ -252,7 +306,7 @@ printf("%d,%d (%s)\n",ii+1,1,rv);
},
decode : func(v)
{
var l = mp_broadcast.Binary.decodeByte(v);
var l = BinaryAsciiTransfer.decodeInt(v);
var rv = substr(v,1,l-1);
print("String decode l=",l," val=",rv);
return rv;
@ -263,11 +317,11 @@ var TransferByte =
{
encode : func(v)
{
return mp_broadcast.Binary.encodeByte(v);
return BinaryAsciiTransfer.encodeInt(v);
},
decode : func(v)
{
return mp_broadcast.Binary.decodeByte(v);
return BinaryAsciiTransfer.decodeInt(v);
}
};
@ -275,23 +329,22 @@ var TransferInt =
{
encode : func(v)
{
return mp_broadcast.Binary.encodeInt(v);
return BinaryAsciiTransfer.encodeInt(v);
},
decode : func(v)
{
return mp_broadcast.Binary.decodeInt(v);
return BinaryAsciiTransfer.decodeInt(v);
}
};
var TransferDouble =
var TransferFixedDouble =
{
encode : func(v)
encode : func(v, precision=4)
{
return mp_broadcast.Binary.encodeDouble(v);
return BinaryAsciiTransfer.encodeInt(v*math.exp(math.ln(10) * precision));
},
decode : func(v)
decode : func(v, precision=4)
{
return mp_broadcast.Binary.decodeDouble(v);
return BinaryAsciiTransfer.decodeInt(v)/math.exp(math.ln(10) * precision);
}
};