Warning!
You are viewing this exercise in a course that you are not a member of. You won't appear on your teacher's scoresheets until you register.
Warning! It seems that you are using Dodona within another webpage, so not everything may work properly. Let your teacher know so that he can solve the problem by adjusting a setting in the learning environment. In the meantime, you can click this link to open Dodona in a new window.
Sign in to test your solution.
The deadline for this exercise is at 17:15, which is less than 5 minutes away.
The deadline for this exercise was at 2020-08-21 17:15. You can still submit, but your submissions may not be accounted for.
decToChar () {
# converts single-byte decimal value to equivalent character
# arg: decimal number from 0-255
# out: one character
echo -n -e "\x$(printf %02X "$1")"
}
readDecimal() {
# Read the n'th decimal from a file. This function looks at the 2 least significant bits of 4 consecutive bytes in
# the given file and pastes them together to decode the decimal.
# arg1: decimal offset
# arg2: filename from which the given decimal should be read and decoded.
readcharDec () {
# read one character from file & convert to equivalent decimal value
# arg1: offset (# of bytes to skip before reading)
# arg2: filename
# out: decimal value from 0-255
VAL=$(xxd -p -l1 -s $1 $2)
printf %d "0x$VAL"
}
readLSB2 () {
# read the 2 LSB's from the byte at the given position in the given file.
# arg1: byte offset
# arg2: filename
READ_BYTE=$(readcharDec $1 $2)
echo $(( READ_BYTE & 3 ))
}
CURRENT_DECIMAL=0
IDX=$1
FILE=$2
for ((j = 3; j > 0; j--)); do
CURRENT_VAL=$(readLSB2 $(( IDX * 4 + j )) $FILE)
CURRENT_DECIMAL=$(( (CURRENT_DECIMAL | CURRENT_VAL) << 2 ))
done
CURRENT_VAL=$(readLSB2 $(( IDX * 4 )) $FILE)
CURRENT_DECIMAL=$(( (CURRENT_DECIMAL | CURRENT_VAL) ))
echo "$CURRENT_DECIMAL"
}
You can submit as many times as you like. Only your latest submission will be taken into account.
Sign in to test your solution.