#!/bin/bash

/* patchkernel: Patch 2.9 BSD kernel

   Copyright (c) 1997-2024, Tarik Isani (xhomer@isani.org)

   This file is part of Xhomer.

   Xhomer is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License version 2 
   as published by the Free Software Foundation.

   Xhomer is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with Xhomer; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/


# This script takes the following parameters and creates a patched
# maintenance1.dsk floppy image and a patched RD kernel:
#
# patch_kernel disk_name cylinders heads sectors num_root_cyl num_swap_cyl
#
# Example: patch_kernel rd31 615 4 16 70 30

# XXX Starting cylinder for rd0c must be <= 255 (can be fixed in script if needed)
# XXX Warning: When updating kernel.dsk or maintenance1.dsk, one must ensure that the
#     search strings (below) do not cross 512-byte sector boundaries.

if [ "$#" -ne 6 ]; then
  echo ""
  echo "Usage: patch_kernel disk_name cylinders heads sectors root_cylinders swap_cylinders"
  echo ""
  echo "Example: patch_kernel rd31 615 4 16 70 30"
  echo ""
  exit
fi

NAME=$1

C=$2

H=$3

S=$4

RC=$5

SC=$6

UNIX=unix
MAINT1=maintenance1
KERNEL=kernel

echo ""
echo "Generating files for: ${NAME}"
echo ""

# Sectors per cylinder

SPC=`expr $H \* $S`

# Generate replacement CHS line for new disk geometry

H_H=`printf "%02x" "$H"`

S_H=`printf "%02x" "$S"`

SPC_H=`printf "%02x" "$SPC"`

SPC_B0=`expr ${SPC} % 256`
SPC_B1=`expr ${SPC} / 256`

SPC_B0_H=`printf "%02x" "$SPC_B0"`
SPC_B1_H=`printf "%02x" "$SPC_B1"`

C_M_1=`expr $C - 1`

C_B0=`expr ${C_M_1} % 256`
C_B1=`expr ${C_M_1} / 256`

C_B0_H=`printf "%02x" "$C_B0"`
C_B1_H=`printf "%02x" "$C_B1"`

CHS="${S_H} 00 ${H_H} 00 ${SPC_B0_H} ${SPC_B1_H} ${C_B0_H} ${C_B1_H}"

echo "Disk geometry:"
echo ""
echo "  Cylinders: $C Heads: $H Sectors: $S"
echo ""
echo "  rd.c patch: $CHS"
echo ""

# Generate partition table entries

# Starting cylinder numbers

SCYL_A=1
SCYL_B=`expr ${SCYL_A} + ${RC}`
SCYL_C=`expr ${SCYL_B} + ${SC}`

SCYL_A_H=`printf "%02x" "${SCYL_A}"`
SCYL_B_H=`printf "%02x" "${SCYL_B}"`
SCYL_C_H=`printf "%02x" "${SCYL_C}"`

# Blocks in rd0a

BLOCKS_A=`expr $RC \* $SPC`

BLOCKS_A_B0=`expr ${BLOCKS_A} % 256`
BSHIFT=`expr ${BLOCKS_A} / 256`
BLOCKS_A_B1=`expr ${BSHIFT} % 256`
BSHIFT=`expr ${BSHIFT} / 256`
BLOCKS_A_B2=`expr ${BSHIFT} % 256`
BLOCKS_A_B3=`expr ${BSHIFT} / 256`

BLOCKS_A_B0_H=`printf "%02x" "${BLOCKS_A_B0}"`
BLOCKS_A_B1_H=`printf "%02x" "${BLOCKS_A_B1}"`
BLOCKS_A_B2_H=`printf "%02x" "${BLOCKS_A_B2}"`
BLOCKS_A_B3_H=`printf "%02x" "${BLOCKS_A_B3}"`

BLOCKS_A_D_2=`expr ${BLOCKS_A} / 2`

# Blocks in rd0b

BLOCKS_B=`expr $SC \* $SPC`

BLOCKS_B_B0=`expr ${BLOCKS_B} % 256`
BSHIFT=`expr ${BLOCKS_B} / 256`
BLOCKS_B_B1=`expr ${BSHIFT} % 256`
BSHIFT=`expr ${BSHIFT} / 256`
BLOCKS_B_B2=`expr ${BSHIFT} % 256`
BLOCKS_B_B3=`expr ${BSHIFT} / 256`

BLOCKS_B_B0_H=`printf "%02x" "${BLOCKS_B_B0}"`
BLOCKS_B_B1_H=`printf "%02x" "${BLOCKS_B_B1}"`
BLOCKS_B_B2_H=`printf "%02x" "${BLOCKS_B_B2}"`
BLOCKS_B_B3_H=`printf "%02x" "${BLOCKS_B_B3}"`

BLOCKS_B_D_2=`expr ${BLOCKS_B} / 2`

# Blocks in rd0c

# To calc. rd0c blocks: blocks = (cyl - num_root_cyl - num_swap_cyl - 2) * heads * sectors

BLOCKS=`expr $C \* $SPC - ${SCYL_C} \* $SPC - $SPC`

BLOCKS_B0=`expr ${BLOCKS} % 256`
BSHIFT=`expr ${BLOCKS} / 256`
BLOCKS_B1=`expr ${BSHIFT} % 256`
BSHIFT=`expr ${BSHIFT} / 256`
BLOCKS_B2=`expr ${BSHIFT} % 256`
BLOCKS_B3=`expr ${BSHIFT} / 256`

BLOCKS_B0_H=`printf "%02x" "${BLOCKS_B0}"`
BLOCKS_B1_H=`printf "%02x" "${BLOCKS_B1}"`
BLOCKS_B2_H=`printf "%02x" "${BLOCKS_B2}"`
BLOCKS_B3_H=`printf "%02x" "${BLOCKS_B3}"`

BLOCKS_D_2=`expr ${BLOCKS} / 2`

IMAGE_SIZE=`expr $C \* $H \* $S \* 512`

PTABLE_A="${BLOCKS_A_B2_H} ${BLOCKS_A_B3_H} ${BLOCKS_A_B0_H} ${BLOCKS_A_B1_H} ${SCYL_A_H} 00"

PTABLE_B="${BLOCKS_B_B2_H} ${BLOCKS_B_B3_H} ${BLOCKS_B_B0_H} ${BLOCKS_B_B1_H} ${SCYL_B_H} 00"

PTABLE_C="${BLOCKS_B2_H} ${BLOCKS_B3_H} ${BLOCKS_B0_H} ${BLOCKS_B1_H} ${SCYL_C_H} 00"

PTABLE="${PTABLE_A} ${PTABLE_B} ${PTABLE_C}"

echo "Partition table:"
echo ""
echo "  Sectors  Cyl.  Partition  Notes"
echo "  -------  ----  ---------  -----"
printf "   %6d  %4d  /dev/rd0a  (mkfs /dev/rd0a %d)\n" ${BLOCKS_A} ${SCYL_A} ${BLOCKS_A_D_2}
printf "   %6d  %4d  /dev/rd0b  (Max. swap %d KB)\n" ${BLOCKS_B} ${SCYL_B} ${BLOCKS_B_D_2}
printf "   %6d  %4d  /dev/rd0c  (mkfs /dev/rd0c %d)\n" ${BLOCKS} ${SCYL_C} ${BLOCKS_D_2}
echo ""
echo "  ioconf.c patch: $PTABLE"

echo ""
echo "Disk image size: ${IMAGE_SIZE} bytes"
echo ""
echo "-----------------------------------------------------------------------------------"
echo ""

# Patch maintenance1.dsk, kernel.dsk and unix

CHS_ORIG="10 00 04 00 40 00 31 01 10 00 04 00 40 00 98 00"

CHS_REPLACE="$CHS 00 00 00 00 00 00 00 00"

PTABLE_ORIG="00 00 80 11 01 00 00 00 80 07 47 00 00 00 00 33 65 00 00 00 c0 0c 65 00"

PTABLE_REPLACE="$PTABLE 00 00 00 00 00 00"

# "RD51 - 0 or RD50 - 1"

RDFMT_ORIG="52 44 35 31 20 2d 20 30 20 6f 72 20 52 44 35 30 20 2d 20 31"

# " Enter 0 at prompt  "

RDFMT_REPLACE="20 45 6e 74 65 72 20 30 20 61 74 20 70 72 6f 6d 70 74 20 20"

# /rdboot patch to adjust cylinder size

RDBOOT_ORIG_SPC="17 72 40 00 80 0a"

RDBOOT_REPLACE_SPC="17 72 ${SPC_B0_H} ${SPC_B1_H} 80 0a"

# /rdboot patch to adjust sectors per track

RDBOOT_ORIG_S="17 72 10 00 1f 10"

RDBOOT_REPLACE_S="17 72 ${S_H} 00 1f 10"

# /boot patch to change boot offset

# "rd(0,64)unix" (plus two null bytes)

BOOT_ORIG="72 64 28 30 2c 36 34 29 75 6e 69 78 00 00"

# "rd(0,xxx)unix" (plus one null byte) - xxx is cylinder offset (64, 96 or 128)

SPC_D=`printf "%03d" "$SPC"`

SPC_D_0=`expr ${SPC_D} % 10 + 48`
BSHIFT=`expr ${SPC_D} / 10`
SPC_D_1=`expr ${BSHIFT} % 10 + 48`
SPC_D_2=`expr ${BSHIFT} / 10 + 48`

SPC_D_0_H=`printf "%02x" "${SPC_D_0}"`
SPC_D_1_H=`printf "%02x" "${SPC_D_1}"`
SPC_D_2_H=`printf "%02x" "${SPC_D_2}"`

BOOT_REPLACE="72 64 28 30 2c ${SPC_D_2_H} ${SPC_D_1_H} ${SPC_D_0_H} 29 75 6e 69 78 00"

# Patch unix

xxd -p $UNIX | fold -w2 | paste -sd' ' | sed "s/${CHS_ORIG}/${CHS_REPLACE}/g" | sed "s/${PTABLE_ORIG}/${PTABLE_REPLACE}/g" | xxd -p -r > ${UNIX}.${NAME}

# Patch maintenance1.dsk

xxd -p ${MAINT1}.dsk | fold -w2 | paste -sd' ' | sed "s/${CHS_ORIG}/${CHS_REPLACE}/g" | sed "s/${PTABLE_ORIG}/${PTABLE_REPLACE}/g" | sed "s/${RDFMT_ORIG}/${RDFMT_REPLACE}/g" | xxd -p -r > ${MAINT1}_${NAME}.dsk

# Patch kernel.dsk

xxd -p ${KERNEL}.dsk | fold -w2 | paste -sd' ' | sed "s/${CHS_ORIG}/${CHS_REPLACE}/g" | sed "s/${PTABLE_ORIG}/${PTABLE_REPLACE}/g" | sed "s/${RDBOOT_ORIG_SPC}/${RDBOOT_REPLACE_SPC}/g" | sed "s/${RDBOOT_ORIG_S}/${RDBOOT_REPLACE_S}/g" | sed "s/${BOOT_ORIG}/${BOOT_REPLACE}/g" | xxd -p -r > ${KERNEL}_${NAME}.dsk