zstda2

#!/bin/bash

## hyphop ##

#= ZSTD advanced

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

"

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

chksum="xxhsum -H2"
chkname="xxh128sum"

ZSTD_HDR(){
hdr_sz=$1
echo "[i] zstd header $1">&2
hdr_sx=$(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"
CMP=""

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

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

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

zstd -T0 -c $CMP $IN >> $OUT

#exit 0

# UNPACK_SIZE
S=$(stat -L -c%s $IN)
# PACKED_SIZE withoud bound tail mark
S0=$(stat -L -c%s $OUT)
S0=$((S0-BS))
SM=${#MARK_FILE_END}
S1=$((S0+ZSTD_HDR_SIZE))
S2=$((S1/BS*BS))

[ $S2 = $S1 ] || S2=$((S2+BS))
S21=$((S2-S1))
S22=$((S21))
echo "[i] S: $S => S0: $S0 => S1: $S1 => S2: $S2 S21: $S21 S22: $S22"

ZSTD_HDR $((S22)) >> $OUT
printf "%${S22}s" " " >> $OUT

ls -l1 $OUT
SIZE_=$(stat -c%s $OUT)
SIZE_CHK=$((SIZE_/BS*BS))

[ $SIZE_ = $SIZE_CHK ] || {
    echo "[e] wrong output size not div by $SIZE_ != $SIZE_CHK /// $BS">&2
}

exit 0

for IN_CHKSUM in $(dd if=$IN bs=$BS  2>/dev/null | $chksum); do
break
done

for OUT_CHKSUM in $(dd if=$OUT bs=$BS skip=1 2>/dev/null | $chksum); do
break
done


(
ZSTD_HDR $BH
echo "
$IN
$MARK_INFO_BEGIN
FILE_NAME: $IN
FMT: zstd
UNPACK_SIZE: $S
PACKED_SIZE: $S0
FILE_SIZE: $((S1+BS))
HEADER_SIZE: $BS
DATA_SIZE: $S1
BOUND_SIZE: $((S1+BS-S0))
OUT-$chkname: $OUT_CHKSUM
IN-$chkname: $IN_CHKSUM
$MARK_INFO_END
"
) | dd of=$OUT conv=notrunc

file $OUT && zstd -l $OUT