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Tools/bash/base.sh

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#!/usr/bin/env bash
#
# base.sh - convert decimal numbers from/to base 2, 8, 10 and 16.
#
# (C) Bruno Raoult ("br"), 2024
# Licensed under the GNU General Public License v3.0 or later.
# Some rights reserved. See COPYING.
#
# You should have received a copy of the GNU General Public License along with this
# program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
#
# SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
#
CMDNAME=${0##*/} # script name
# some default values (blocks separator padchar)
# Attention: For output base 10, obase is 1
declare -i ibase=0 obase=0 padding=0 prefix=1 ogroup=0 intbits
# find out int size (bits) - suppose 2-complement, and 8 bits char
printf -v _b "%x" -1
(( intbits = ${#_b} * 4 ))
declare -rA _bases=( # -f/-b accepted values
[2]=2 [b]=2 [B]=2
[8]=8 [o]=8 [O]=8
[10]=10 [d]=10 [D]=10
[16]=16 [h]=16 [H]=16
[a]=-1 [g]=-1
)
declare -A _pad=( # group separator
[2]=" " [8]=" " [10]="," [16]=" "
)
declare -rA _ogroup=( # group size
[2]=8 [8]=3 [10]=3 [16]=4
)
declare -rA _oprefix=( # output prefix
[2]="2#" [8]="0" [10]="" [16]="0x"
)
usage() {
printf "usage: %s [OPTIONS] [NUMBER]...\n" "$CMDNAME"
printf "Use '%s -h' for more help\n" "$CMDNAME"
}
help() {
cat << _EOF
usage: $CMDNAME [OPTIONS] [NUMBER]...
-f, --from=BASE input base, see BASE below. Default is "g"
-t, --to=BASE output base, see BASE below. Default is "a"
-b, -o, -d, -x equivalent to -t2, -t8, -t10, -t16"
-g, --group=[SEP] group output (see OUTPUT below)
-p, --padding 0-pad output on block boundary (implies -g)
-n, --noprefix remove base prefixes in output
-h, --help this help
-- end of options
$CMDNAME output the NUMBERS arguments in different bases. If no NUMBER is
given, standard input will be used.
BASE
2, b, B binary
8, o, O, 0 octal
10, d, D decimal
16, h, H, 0x hexadecimal
a, g all/any: Default, guess format for '-f', output all
bases for '-t'
INPUT NUMBER
If input base is not specified, some prefixes are supported.
'b' or '2/' for binary, '0', 'o' or '8/' for octal, '0x', 'x' or
'16/' for hexadecimal, and 'd' or '10/' for decimal.
If no above prefix is found, decimal is assumed.
Decimal input may be signed or unsigned, with limits imposed by current
Bash (here: $intbits bits).
OUTPUT
Decimal output is always unsigned.
By default, the input number is shown converted in the 4 supported
bases (16, 10, 8, 2, in this order), separated by one tab character.
Without '-n' option, all output numbers but decimal will be prefixed:
'2#' for binary, '0' for octal, '0x' for hexadecimal, making them
usable for input in some otilities such as bash(1).]
With '-g' option, number digits will be grouped by 3 (octal,
decimal), 4 (hexadecimal), or 8 (binary). If no SEP character is given,
the separator will be ',' (comma) for decimal, space otherwise.
This option may be useless for default output, with multiple numbers
on one line.
The '-p' option add 0 padding up to the base grouping boundary.
EXAMPLES
Converting number in hexadecimal, decimal, octal, and binary, with or without
prefixes. Here, '\t' separator is shown as space:
$ $CMDNAME 0
0x0 0 0 2#0
$ $CMDNAME 123456
0x1e240 123456 0361100 2#11110001001000000
$ $CMDNAME -n 2/100
4 4 4 100
$ $CMDNAME -n 0x1e240
1e240 123456 361100 11110001001000000
Binary output, no prefix, grouped output:
$ $CMDNAME -bng 0x1e240
1 11100010 01000000
Negative input (decimal only):
$ $CMDNAME -x -- -1
0xffffffffffffffff
Input base indication, left padding binary output, no prefix:
$ $CMDNAME -nbp -f8 361100
00000001 11100010 01000000
Set group separator. Note that the separator *must* immediately follow the '-g'
option, without spaces:
$ $CMDNAME -nxg: 123456
1:e240
Long options, with separator and padding:
$ $CMDNAME --to=16 --noprefix --padding --group=: 12345
0001:e240
TODO
Add option for signed/unsigned integer output.
Remove useless octal output ?
_EOF
}
zero_pad() {
local n="$1" str="$2"
printf "%0.*d%s" $(( n - ${#str} % n)) 0 "$str"
}
split() {
local base="$1" str="$2"
local res="$str" sep=${_pad[$base]}
local -i n=${_ogroup[$base]}
(( padding )) && str=$(zero_pad "${_ogroup[$base]}" "$str")
if (( ogroup )); then
res=""
while (( ${#str} )); do
if (( ${#str} <= n )); then # finished
res="${str}${res:+$sep$res}"
break
fi
res="${str: -n}${res:+$sep$res}"
str="${str:0:-n}"
done
fi
printf "%s" "$res"
}
bin() {
local str=""
local -i n dec="$1"
# take care of negative numbers, as >> operator keeps the sign.
# 'intbits' is size of integer in bits in current shell.
for (( n = 0 ; dec && (n < intbits); n++ )); do
str="$(( dec & 1 ))$str"
(( dec >>= 1 ))
done
printf "%s\n" "${str:-0}"
}
hex() {
printf "%lx" "$1"
}
dec() {
printf "%lu" "$1"
}
oct() {
printf "%lo" "$1"
}
declare -a args=()
parse_opts() {
# short and long options
local sopts="f:t:bodxg::pnh"
local lopts="from:,to:,group::,padding,noprefix,help"
# set by options
local tmp=""
if ! tmp=$(getopt -o "$sopts" -l "$lopts" -n "$CMDNAME" -- "$@"); then
usage
exit 1
fi
eval set -- "$tmp"
while true; do
case "$1" in
"-f"|"--from")
ibase=${_bases[$2]}
if (( ! ibase )); then
usage
exit 1
fi
shift
;;
"-t"|"--to")
obase=${_bases[$2]}
if (( ! obase )); then
usage
exit 1
fi
shift
;;
"-b") obase=2 ;;
"-o") obase=8 ;;
"-d") obase=1 ;;
"-x") obase=16 ;;
"-g"|"--group")
ogroup=1
if [[ -n "$2" ]]; then
for i in 2 8 10 16; do _pad["$i"]="$2"; done
fi
shift
;;
"-p"|"--padding") ogroup=1; padding=1 ;;
"-n"|"--noprefix") prefix=0 ;;
"-h"|"--help") help ; exit 0 ;;
"--") shift; break ;;
*) usage; echo "Internal error [$1]!" >&2; exit 1 ;;
esac
shift
done
# next are numbers to convert, if any
if (($# > 0)); then
args=("$@")
fi
}
addprefix() {
local base="$1" number="$2" _prefix=""
if (( prefix )); then
if [[ $base != 8 || $number != "0" ]]; then
_prefix="${_oprefix[$base]}"
fi
fi
printf "%s%s" "$_prefix" "$number"
}
stripprefix() {
[[ $1 =~ ^(0x|b|o|d|x|.*/) ]]
printf "%s" "${1#"${BASH_REMATCH[1]}"}"
}
guessbase() {
local input="$1"
local -i base=0
if [[ $input =~ ^(b|2/) ]]; then
base=2
elif [[ $input =~ ^(0x|x|16/) ]]; then
base=16
elif [[ $input =~ ^(0|o|8/) ]]; then
base=8
elif [[ $input =~ ^(d|10/) ]]; then
base=10
fi
return $(( base ? base : 10 ))
}
doit() {
local number="$2" multi="" val inum
local -i base=$1 decval _obase=$obase
if (( base <= 0 )); then
guessbase "$number"
base=$?
fi
inum=$(stripprefix "$number")
# convert input value to decimal
(( base == 10 )) && (( decval = inum ))
(( base != 10 )) && (( decval = "$base#$inum" ))
# mask for desired output: 1=decimal, others are same as base
if (( ! _obase )); then
(( _obase = 1|2|8|16 ))
multi=$'\t'
fi
if (( _obase & 16 )); then
val=$(addprefix 16 "$(split 16 "$(hex $decval)")")
printf "%s%s" "$val" "$multi"
fi
if (( _obase & 1 )); then
val=$(addprefix 10 "$(split 10 "$(dec $decval)")")
printf "%s%s" "$val" "$multi"
fi
if (( _obase & 8 )); then
val=$(addprefix 8 "$(split 8 "$(oct $decval)")")
printf "%s%s" "$val" "$multi"
fi
if (( _obase & 2 )); then
val=$(addprefix 2 "$(split 2 "$(bin $decval)")")
printf "%s%s" "$val" "$multi"
fi
printf "\n"
}
parse_opts "$@"
if ! (( ${#args[@]} )); then
while read -era line; do
for input in "${line[@]}"; do
doit "ibase" "$input"
done
done
else
for input in "${args[@]}"; do
doit "$ibase" "$input"
done
fi
exit 0