zstda

#!/bin/bash

## hyphop ##

#= ZSTD advanced

ZSTDA="
 _________ _____ ____    _    
|__  / ___|_   _|  _ \  / \   
  / /\___ \ | | | | | |/ _ \  
 / /_ ___) || | | |_| / ___ \ 
/____|____/ |_| |____/_/   \_\

"

#+ zstd image header
#+ 4096 block size padding
#+ zstd image tail

ZSTD_HDR(){
hdr_sz=$1
hdr_sx=$(printf "%08x" $1)

#########
#01234567
#########

h1=${hdr_sx:6:2}
h2=${hdr_sx:4:2}
h3=${hdr_sx:2:2}
h4=${hdr_sx:0:2}

printf "%b" '\x50\x2A\x4D\x18'
printf "%b" "\x$h1\x$h2\x$h3\x$h4"

}

MARK_INFO_BEGIN="
##ZSTD_INFO
"
MARK_INFO_END="
##ZSTD-INFO
"
MARK_FILE_END="
##ZSTD#END
"

BS=4096
ZSTD_HDR_SIZE=8

IN=$1

[ "$IN" ] || {
    echo "[w] undef input file">&2
    exit 1
}

OUT=$2

CMP="--ultra -22"

[ "$OUT" ] || OUT="$IN.zstd"

BH=$((BS-$ZSTD_HDR_SIZE))
ZSTD_HDR $BH > $OUT

printf "%${BH}s" " " >> $OUT

xxhsum="xxhsum -C2"

(
zstd -T0 -c $CMP $IN

#exit 0

S=$(stat -L -c%s $IN)
S0=$(stat -L -c%s $OUT)
S0=$((S0-$BS))
S1=$((S0/$BS*$BS))
[ "$S1" = "$S0" ] || S1=$((S1+$BS))
S3=$((S1-$S0-$ZSTD_HDR_SIZE))
SM=${#MARK_FILE_END}

[ "$S3" -lt "$SM" ] && {
    S3=$((S3+$BS))
}

S4=$((S3-$SM))

echo "[i] S4 $S4 + $SM == S3 $S3 .. $S0 => $S1">&2

ZSTD_HDR $BS
printf "%${S4}s${MARK_FILE_END}" " "

) | $xxhsum >> $OUT 2>/tmp/xxhsum.txt
#) >> $OUT

xxhsum=$(cat /tmp/xxhsum.txt)

(
ZSTD_HDR $BH
echo "$IN"
echo "xxh128sum: $xxhsum"
) | dd of=$OUT conv=notrunc

#dd if=$OUT bs=$BS skip=1 | $chksum
#ls -l1 $OUT

file $OUT && zstd -l $OUT