#!/bin/sh
######################################################################
#
# Determine which endian the processor uses to store numbers.
#
# SYNOPSIS
#
#	endian
#	endian big
#	endian little
#
# DESCRIPTION
#
#	This script attempts to determine the endianness of the processor it is
#	running under. http://en.wikipedia.org/wiki/Endianness
#
#	This script may be run in two modes. In the first mode you simply call
#	"endian" with no options and it will print a string "little" or "big"
#	depending on what endianness was found. In the second mode you pass an
#	option of either "big" or "little" and the script will exit 0 if the
#	endianness matches or will exit 1 if the endianness does not match.
#
# EXAMPLES
#
#	$ endian
#	little
#
#	$ if [ "$(endian)" = "little" ]; then echo "Running on a little endian system."; fi
#	Running on a little endian system.
#
#	$ if endian little; then echo "Running on a little endian system."; fi
#	Running on a little endian system.
#
# EXIT STATUS
#
#	This script exits with status 0 if the endianness matches the argument,
#	or it exits with 1 if the endianness does not match.
#
# AUTHOR
#
#	Noah Spurrier <noah@noah.org>
#
# LICENSE
#
#     This license is OSI and FSF approved as GPL-compatible.
#     This license identical to the ISC License and is registered with and
#     approved by the Open Source Initiative. For more information vist:
#         http://opensource.org/licenses/isc-license.txt
#
#     Copyright (c) 2011, Noah Spurrier
#
#     Permission to use, copy, modify, and/or distribute this software for any
#     purpose with or without fee is hereby granted, provided that the above
#     copyright notice and this permission notice appear in all copies.
#
#     THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
#     WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
#     MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
#     ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
#     WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
#     ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
#     OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#
# VERSION
#
#     Version 1
#
######################################################################

LAST_DIGIT_OCT_INT="$(echo -n pq | hexdump | head -n 1 | sed -e "s/^.*\([0-9a-fA-F]\)[ \t\n]*$/\1/")"
if [ "${LAST_DIGIT_OCT_INT}" = "0" ]; then
	ENDIAN_LITTLE=1
	ENDIAN_BIG=0
elif [ "${LAST_DIGIT_OCT_INT}" = "1" ]; then
	ENDIAN_LITTLE=0
	ENDIAN_BIG=1
else
	echo "ERROR: Did not get last digit of hex integer." 1>&2
	exit 1
fi

if [ "$1" = "little" ]; then
	exit ${ENDIAN_BIG}
fi

if [ "$1" = "big" ]; then
	exit ${ENDIAN_LITTLE}
fi

if [ $ENDIAN_LITTLE -eq 1 ]; then
	echo "little"
fi
if [ $ENDIAN_BIG -eq 1 ]; then
	echo "big"
fi

#####################################################################
# END
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# vim:set sr et ts=4 sw=4 ft=sh: // See Vim, :help 'modeline'