#!/bin/ksh
# fdminor: show meaning of floppy drive device minor bits
# @(#) fdminor.ksh 1.0 93/02/17
# 93/02/17 john h. dubois iii (john@armory.com)

name=${0##*/}

if [ $# -eq 0 -o "$1" = -h ]; then
	echo \
"$name: show meaning of floppy drive device node minor number.
Syntax: $name [-h] <minor_num>|<device-name> ...
The meaning of the bit fields of the minor number will be printed.
If a device name is given, its minor number is looked up.
Options: -h prints this help.

Minor number meaning:
bits	meaning			value
7	ignore cylinder 0	0: use cylinder 0; 1: skip cylinder 0
6	autodetect floppy type	0: no autodetect; 1: autodetect
				(bits 5..3 should be 0)
5	tracks per side		0: 40 tracks/side; 1: 80 tracks/side
4,3	sectors per track	0: 9 spt; 1: 8 spt; 2: 15 spt; 3: 18 spt
2	sides			0: single sided; 1: double sided
2,1	floppy drive number	0..3: drive number 0..3"
    exit
fi

set -A sptvals 9 8 15 18
set -A trackvals 40 80

device=

alias istrue="test 0 -ne"
alias isfalse="test 0 -eq"

function fdminor {
    typeset IFS=" ," device
    typeset -i10 major minor cylinder0 autodetect tracks spt sides drivenum

    case "$1" in
    [0-9]*) minor=$1;;
    ./*|../*|/*) device=$1;;
    *) device=/dev/$1;;
    esac

    if [ -n "$device" ]; then
	set -- `l $device`
	[ -z "$6" ] && return
	if [[ "$1" != [cb]* ]]; then
	    echo "$device is not a device file."
	    return
	fi
	major=$5
	minor=$6
	if [[ "$5" != 2 ]]; then
	    echo "Warning: $device is not a floppy device."
	fi
	echo "Device $device (minor number $minor):"
    else
	echo "Minor number $minor:"
    fi

    if [ $minor -gt 255 -o $minor -lt 0 ]; then
	    echo "Minor number must be in the range 0-255!"
	    exit 1
    fi

    cylinder0="minor&2#10000000"
    autodetect="minor&2#1000000"
    tracks="${trackvals[$(((minor&2#100000)>>5))]}"
    spt="${sptvals[$(((minor&2#11000)>>3))]}"
    sides="((minor&2#100)>>2)+1"
    drivenum="minor&2#11"

    isfalse cylinder0 && print "Uses cylinder 0" || print "Skips cylinder 0"

    if istrue autodetect; then
	print "tracks/side, sectors/track, sides: autodetected"
    else
	print "$tracks tracks/side"
	print "$spt sectors/track"
	print "$sides side(s)"
	istrue cylinder0 && tracks=tracks-1
	capacity=$((tracks * spt * sides * 512))
	print "Capacity: $capacity bytes ($((capacity / 1024))K)"
    fi
    print "drive number: $drivenum"
}

fdminor "$1"
shift

for arg; do
    echo ""
    fdminor "$arg"
done