zstd_header2

#!/bin/bash

## hyphop ##

#=  zstd image header
#=  zstd image tail
#= kresq image tail

MSG="$1"
hdr_sz=${#MSG}
hdr_sx=$(printf "%08x" ${#MSG})

#echo "$hdr_sx">&2

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

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

#echo "\x$h1\x$h2\x$h3\x$h4">&2

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