Re: manipulating bits not bytes-Enthusiasts level question

[David Manura <dm.lua@...>]

On Sat, Sep 4, 2010 at 9:15 AM, Patrick Mc(avery >
> bin = io.open('29fb.bin', 'r') --29fb is 512 KB I am on Linux no "rb"
> bin_all = bin:read("*all")
> bin_zero, ntimes  = bin_all.gsub(bin_all, '1', '0')
> print(ntimes) --> 20 --should be way more times then this

If you want to count the number of 1's in binary data, I suggest
creating a lookup table that maps each byte (0-255) to the number of
1's in that byte.  Then sum each byte after translating via that
table.

> Is there also a way to read one bit? read(1) is one byte, is there a way to
> read one bit?

The Lua implementation of the DEFLATE algorithm processes bits at a time. [1]

[1] http://lua-users.org/wiki/ModuleCompressDeflateLua