Am 23.01.2012 19:38, schrieb Jan Kiszka:
Forking an expr process for every byte of the input data slows down the checksum calculation massively. Fix this while still remaining portable by implementing the algorithm in awk.Signed-off-by: Jan Kiszka<jan.kis...@siemens.com> --- That "remaining portable" is an unproven claim. So please check that problematic NetBSD and also mingw. Thanks! scripts/signrom.sh | 18 ++++++++---------- 1 files changed, 8 insertions(+), 10 deletions(-) diff --git a/scripts/signrom.sh b/scripts/signrom.sh index 9dc5c63..f0f460e 100755 --- a/scripts/signrom.sh +++ b/scripts/signrom.sh @@ -23,22 +23,20 @@ # did we get proper arguments? test "$1" -a "$2" || exit 1 -sum=0 - # find out the file size x=`dd if="$1" bs=1 count=1 skip=2 2>/dev/null | od -t u1 -A n` -#size=`expr $x \* 512 - 1` size=$(( $x * 512 - 1 )) # now get the checksum nums=`od -A n -t u1 -v -N $size "$1"` -for i in ${nums}; do - # add each byte's value to sum - sum=`expr \( $sum + $i \) % 256` -done - -sum=$(( (256 - $sum) % 256 )) -sum_octal=$( printf "%o" $sum ) +sum_octal=`echo $nums | awk 'BEGIN { + getline data_str; + sum = 0; + n = split(data_str, data, " "); + for (i = 1; i<= n; i++) + sum = ( sum + data[i] ) % 256; + printf "%o", (256 - sum) % 256; +}'` # and write the output file cp "$1" "$2"
What about replacing the whole script by a python script? That would save about 6 more forks :-) I'd prefer if we could get rid of all AWK dependencies in QEMU and focus on as few scripting languages as reasonable. Regards, Stefan W.
