While your version took 12 seconds for 16MB on my system:

C:\test>dir 1123355.bin
14/04/2015  16:50        16,777,216 1123355.bin

C:\test>1159245 1123355.bin
Took 12.897612 secs

[download]

(That was the third run so the cache was primed.)

This version took:

C:\test>1159245 1123355.bin
Took 3.832763 secs
  : 3762666
☺ : 46120
☻ : 43642
♥ : 44106
♦ : 43878
...

[download]

The code;

#! perl -slw
use strict;
use Time::HiRes qw[ time ];

my $start = time;

open I, '<:raw', $ARGV[ 0 ];

my @seen;

while( read( I, my $buf, 16384  ) ) {
    ++$seen[$_] for unpack 'C*', $buf;
}
printf "Took %f secs\n", time() - $start;

printf "%c : %u\n", $_, $seen[$_] for 0 .. 255;

[download]

In reply to Re: Count byte/character occurrence (1/4) by BrowserUk
in thread Count byte/character occurrence (quickly) by james28909

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