#! /bin/bash

set -e -o pipefail
prog=${0##*/}

case $# in 1) ;; *) echo >&2 "usage: $prog DEV"; exit 127 ;; esac
dev=$1

typeset -i sz; sz=$(blockdev --getsize64 "$dev")
k=$(gorp -fhex 256)

## Figure out a useful block size.
typeset -i bsz=1 nb=$sz
for i in 2 3 5 7; do
  while :; do
    case $((nb%i)) in
      0) bsz=$((bsz*i)) nb=$((nb/i)) ;;
      *) break ;;
    esac
    if (( bsz >= 65536 )); then break 2; fi
  done
done
echo >&2 "$prog: using $nb blocks of size $bsz"

## Write the initial stream.
echo >&2 "$prog: writing pseudorandom pattern..."
rspit salsa20/8 -H$k -z$sz -pT | \
  dd status=none iflag=fullblock oflag=direct bs=$bsz count=$nb of="$dev"
echo >&2 "$prog: writing pseudorandom pattern... done"

## Read the stream back, and check against the reference.
echo >&2 "$prog: checking pseudorandom pattern..."
cmp <(rspit salsa20/8 -H$k -z$sz -pT) \
    <(dd status=none iflag=direct bs=$bsz count=$nb if="$dev")
echo >&2 "$prog: checking pseudorandom pattern... done"
echo >&2 "$prog: all ok"