#!/bin/env tclsh

proc fatal {num reason} {
	global argv0
	puts stderr "fatal: $argv0: $reason"
	exit $num
}

if {[llength $argv] != 2} {
	puts stderr "usage: $argv0 FILE.PAC OUTDIR/"
	exit 1
}

lassign $argv file dir

set fp [open $file rb]
binary scan [read $fp 0xc] {iii} magic numents startpos

if {$magic != 0x00434150} {
	die 2 "unknown magic: $magic"
} else {
	puts "magic = $magic, OK"
}

set hdrlen [expr {0xc + ($numents * 4)}]
puts "header length: $hdrlen ($numents entries)"
puts "data offset: $startpos"

puts "reading end table..."
set endhdr [read $fp [expr {$numents * 4}]]
binary scan $endhdr "i$numents" endtab
puts $endtab

seek $fp $startpos

file mkdir $dir

set pos $startpos
foreach endpt $endtab {
	set length [expr {$endpt - $pos}]
	set data [read $fp $length]
	set fp2 [open $dir/[format %08x $endpt].bin wb]
	puts $fp2 $data
	close $fp2

	set pos $endpt
}