UNIX for Dummies Questions & Answers

#!/bin/bash

# "decimalstring" is a 24576 byte contiguous 3 byte decimal
# value from 255 to 000 generated from an 8KB binary file...
decimalstring=`hexdump -n8192 -s0 -v -e '1/1 "%03u"' 8KB.dat`

splicedstaing=""
somestring=""
n=0
m=0

# printf "$decimalstring" > 24KB.txt
# printf "$decimalstring"

printf "\nStart!"

# Start position of slow loop.
for splicedstring in $( seq 0 3 24575 )
do
	somestring="${decimalstring:$splicedstring:3}"
	if [ $somestring -ge 128 ]
	then
		m=$[ ( m + 1 ) ]
	fi
	if [ $somestring -le 127 ]
	then
		n=$[ ( n + 1 ) ]
	fi
done
# End position of slow loop.

printf "\n\nDone!, m=$m, n=$n...\n\n"

# printf "$decimalstring"

Last login: Sat May 25 17:26:11 on ttys000
Barrys-MacBook-Pro:~ barrywalker$ ./decimal_string.sh

Start!

Done!, m=4096, n=4096...

Barrys-MacBook-Pro:~ barrywalker$

	if [ $somestring -ge 128 ]
	then
		m=$[ ( m + 1 ) ]
	else
		n=$[ ( n + 1 ) ]
	fi

for splicedstring in $( seq 0 3 24575 )
  do a=$((10#${decimalstring:$splicedstring:3} & 128 >> 7))  # ANDing out bit 7; shift right to bit 1; result is 1 or 0
     m=$((m+=a ))                                            # increment m if bit was set (number >= 128)
     n=$((n+=(1-a)))                                         # increment n if bit was clear
  done

for splicedstring in {0..24575..3}