as3 loop optimization

Question

I have this piece of code:

palette = new Array(paletteSize);
for (var i:int=0;i<paletteSize;i++) {
  palette[i] = 0xFF000000
    | (inputStream.readUnsignedByte() << 16)
    | (inputStream.readUnsignedByte() << 8)
    | (inputStream.readUnsignedByte());
}

This code is executed around 300 times and each time paletteSize varies from 1-255. So, on the whole this code takes around 60-80ms. Can this be optimized in some way? inputStream(IDataInput) is a socket connection and it does not spend any time waiting on i/o. This code is only executed when enough number of bytes are available in stream.

Try use "Vector.<uint>" instead of Array. Also if you control the incoming stream you could send 4-byte colors and read them using readUnsignedInt instead, avoiding the bit shifting. — Ville Krumlinde
– Ville Krumlinde, Commented Nov 19, 2011 at 14:34
I wasn't sure because it's been a while since I did as3-development so I cowardly wrote a comment instead (downvoters are ruthless ;-) ), but I've made it an answer now. — Ville Krumlinde
– Ville Krumlinde, Commented Nov 19, 2011 at 15:08
you could also try loop unwinding to see if it improves anything: en.wikipedia.org/wiki/Loop_unwinding — divillysausages
– divillysausages, Commented Nov 19, 2011 at 15:28

Ville Krumlinde · Accepted Answer · 2011-11-19 15:05:50Z

2

Copied from my comment: Try use "Vector." instead of Array. Also if you control the incoming stream you could send 4-byte colors and read them using readUnsignedInt instead, avoiding the bit shifting.

answered Nov 19, 2011 at 15:05

Ville Krumlinde

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2 Comments

Nakul Over a year ago

I need to an array only, since it goes to bitmapdata.paletteMap() :( and i don't have control over incoming stream either

Ville Krumlinde Over a year ago

I see. Perhaps read both R and G as a single 16-bit short with "(inputStream.readUnsignedShort() << 8) | inputStream.readUnsignedByte()" then? Sensitive for endianess though.

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