#!/usr/bin/env bash

MYDIR=$(dirname $0)

mkdir -p ${MYDIR}/.bins

DEFAULT_BASEROM=baserom.nds
DEFAULT_ARM9BUILDDIR=build/heartgold.us
DEFAULT_ARM7BUILDDIR=sub/build
DEFAULT_FSDIR=files

# Build C utils on demand
[[ $MYDIR/ntruncompbw -nt $MYDIR/ntruncompbw.c ]] || gcc -O3 -g -o $MYDIR/ntruncompbw $MYDIR/ntruncompbw.c
[[ $MYDIR/ntrextractfile -nt $MYDIR/ntrextractfile.c ]] || gcc -O3 -g -o $MYDIR/ntrextractfile $MYDIR/ntrextractfile.c

getword() {
  od -j "$2" -N 4 -A n -t u "$1" | awk '{$1=$1};1'
}

[[ -n "$DEVKITARM" ]] && export PATH=${DEVKITARM}/bin:${PATH}

POSITIONAL=()

usage () {
    echo "Diff segments of a Nintendo DS ROM"
    echo "Usage: $0 [-h] [-7] [-m OVERLAY] [-r BASEROM] [-d BUILDDIR] [START [END]]"
    echo ""
    echo "Arguments:"
    echo "  START, END    Start and end virtual addresses to diff"
    echo ""
    echo "Options:"
    echo "  -7            Diff the ARM7 module (default: ARM9)"
    echo "  -m OVERLAY    Diff the indicated overlay module (default: static module)"
    echo "  -r BASEROM    Use the indicated baserom (default: baserom.nds)"
    echo "  -d BUILDDIR   Look for compiled binaries in this directory (default: build/heartgold.us)"
    echo "  -f FILE       Dump the indicated file, and use hexdump instead"
    echo "  -F FSDIR      Filesystem path on the home system"
    echo "  -t            Force THUMB instructions (default: ARM)"
    echo "  -h            Show this message and exit"
}

while [[ $# -gt 0 ]]; do
  key="$1"
  case $key in
  -h)
    usage
    exit 0
    ;;
  -7)
    proc=armv4t
    builddir=${builddir:-$DEFAULT_ARM7BUILDDIR}
    basestem=${basestem}.sub
    shift
    ;;
  -m)
    [[ -n $overlay ]] && { echo can only do one overlay at a time; exit 1; }
    mode=overlay
    overlay="$2"
    basestem=${basestem}.o${overlay}
    shift 2
    ;;
  -r)
    baserom="$2"
    shift 2
    ;;
  -t)
    thumb=-Mforce-thumb
    shift
    ;;
  -f)
    mode=file
    filepath="$2"
    shift 2
    ;;
  -F)
    fsdir="$2"
    shift 2
    ;;
  -d)
    builddir="$2"
    shift 2
    ;;
  -*)
    usage
    echo unrecognized option flag: "$1" >&2
    exit 1
    ;;
  *)
    POSITIONAL+=("$1")
    shift
    ;;
  esac
done

set -- "${POSITIONAL[@]}"

mode=${mode:-static}
proc=${proc:-armv5te}
builddir=${builddir:-$DEFAULT_ARM9BUILDDIR}
baserom=${baserom:-$DEFAULT_BASEROM}
fsdir=${fsdir:-$DEFAULT_FSDIR}

basefile=${MYDIR}/.bins/${baserom}${basestem}.sbin

case "$mode" in
  overlay)
    case $proc in
    armv4t)
      ovt=88
      ;;
    armv5te)
      ovt=80
      ;;
    esac
    ovtoff=$(getword "$baserom" "$ovt")
    vma=$(getword "$baserom" "$((ovtoff+32*overlay+4))")
    size=$(getword "$baserom" "$((ovtoff+32*overlay+8))")
    [[ -f $basefile ]] || {
      fileid=$(getword "$baserom" "$((ovtoff+32*overlay+24))")
      param=$(getword "$baserom" "$((ovtoff+32*overlay+28))")
      fatoff=$(getword "$baserom" 72)
      fileoff=$(getword "$baserom" "$((fatoff+8*fileid))")
      filesize=$(($(getword "$baserom" "$((fatoff+8*fileid+4))")-fileoff))
      dd if="$baserom" of="$basefile" bs=1 skip="$fileoff" count="$filesize" 2>/dev/null
      (( param & 16777216 )) && {
        compsize=$((param & 16777215))
        $MYDIR/ntruncompbw $basefile $vma $((vma+compsize)) || { rm -f $basefile; exit 1; }
      }
    }
    buildfile=$builddir/OVY_${overlay}.sbin
    ;;
  static)
    case $proc in
    armv4t)
      romtab=48
      compname=ichneumon_sub
      ;;
    armv5te)
      romtab=32
      compname=main
      ;;
    esac

    fileoff=$(getword "$baserom" "$romtab")
    vma=$(getword "$baserom" "$((romtab+8))")
    size=$(getword "$baserom" "$((romtab+12))")

    [[ -f $basefile ]] || {
      dd if="$baserom" of="$basefile" bs=1 skip="$fileoff" count="$size" 2>/dev/null
      [[ $proc == armv5te ]] && {
        _start_ModuleParams=$(getword "$baserom" $((fileoff+size+4)))
        compstatend=$(getword "$basefile" $((_start_ModuleParams+20)))
        [[ $compstatend != "0" ]] && {
          $MYDIR/ntruncompbw $basefile $vma $compstatend || { rm -f $basefile; exit 1; }
          dd if=/dev/zero of="$basefile" bs=1 seek="$((_start_ModuleParams+20))" count=4 conv=notrunc 2>/dev/null
        }
      }
    }
    buildfile=${builddir}/${compname}.sbin
    ;;
  file)
    buildfile=${fsdir}/${filepath}
    [[ -f "${buildfile}" ]] || { echo file not found: "${buildfile}"; exit 1; }
    basefile=${MYDIR}/.files/${filepath}
    [[ -f "${basefile}" ]] || {
      mkdir -p $(dirname "${basefile}")
      ${MYDIR}/ntrextractfile ${baserom} ${filepath} >${basefile}
    }
    diff -u <(hexdump -Cv $basefile) <(hexdump -Cv $buildfile)
    exit 0
    ;;
esac

[[ -n "$1" ]] && start=$(($1)) || start=$vma
[[ -n "$2" ]] && size=$(($2)) || size=$(wc -c <$basefile)
do-objdump () {
  arm-none-eabi-objdump -Drz -bbinary -m$proc $thumb --adjust-vma=$vma --start-address=$start --stop-address=$((start+size)) $1
}
diff -u <(do-objdump $basefile) <(do-objdump $buildfile)