#!/bin/bash

declare -x SFK
SFK="${SFK:-$(dirname $(readlink -f ${0}))/sfk}"
[ -x "$SFK" ] || { echo >&2 "ERROR: this script requires sfk tool which is not found on your system, expected location of the tool is \"$SFK\""; exit 1; }

#
# $1 - input file
# $2 - pattern type (bin, pat/text, spat/spats - see "sfk help pat" for details)
# $3 - pattern
#
# returns:
#   offsets of all pattern matches
getHexOffsetsOfAllMatches() {
	"$SFK" hexfind "$1" -$2 "/$3/" -quiet | sed -nr -e 's|.*hit at offset (0x[0-9A-F]+)|\1|p'
}
getDecOffsetsOfAllMatches() {
	local matches=$(getHexOffsetsOfAllMatches "$@")
	[ -z "$matches" ] && return
	echo "$matches" | xargs printf "%d\n"
}

#
# $1 - input file
# $2 - offset
# $3 - length
#
getHexContentAtOffset() {
	"$SFK" hexdump -offlen "$2" "$3" -nofile -pure "$1" | tr -d $'\n'
}

#
# zero pads each line of stdin to number of characters specified in $1
#
# $1 - number of characters to pad to, default 8 if omitted
#
padLeftZero() {
	local numberOfCharsToPadTo="${1:-8}"
	sed -r -e ':zero_pad;s/^(.{1,'"$((numberOfCharsToPadTo-1))"'})((.{'"${numberOfCharsToPadTo}"'})*)$/0\1\2/;tzero_pad'
}

#
# inverts endianness of each line of stdin
# each line is assumed to be a hex-string representation of 32-bit data and is processed separately
# if hex-string length is not muptiple of 8 it is zero padded
#
invertEndianness() {
	padLeftZero 8 | sed -r -e 's/(..)(..)(..)(..)/\4\3\2\1/g'
}

#
# $1 - input file
# $2 - offset
#
getLEu32AtOffset() {
	echo -n $((0x$(getHexContentAtOffset "$1" "$2" 4 | invertEndianness)))
}