base64 encoding using the new binary syntax

[Sean Hinde]

Mattias,

> Since the binary syntax is here now, maybe people are interested in
> exploring its performance characteristics. Here's something to start
> the discussion. Performance of the attached module when en(de)coding
> rfc2045.txt (71kb) on my 167MHz ultrasparc:

Running the profiler (using rfc2719 - 48kB) on my laptop has the following
result:

16> eprof:analyse().
FUNCTION                                       CALLS      TIME 

****** Process <0.56.0>    -- 100 % of profiled time *** 
bitbase64:enc/1                                17116      51 % 
bitbase64:acc_pack/2                           901        30 % 
bitbase64:int_to_b64/1                         64862      19 % 
eprof:call/4                                   1          0 % 
bitbase64:pack/1                               1          0 % 

Total time: 1.60
Measurement overhead: 1.06
ok

I think this means that per call:

acc_pack/1 takes 0.179 mS
enc/1 takes 0.016 ms
int_to_b64 takes 0.00158 mS

All acc_pack is doing is splitting a binary and joining another so this does
seem a little excessive...

Rgds,
Sean



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