#!/usr/bin/perl

# Usage: pipe the output of Linux's `strace' program into the stdin of
# this command, and the output of this command into gnuplot.

$filename = shift || "tstab2.h5";
$total = 0;

while (<>) {
   if (!defined $fd) {
      if (/^open\("(.*?)".*=\s+(\d+)/ && $1 eq $filename) {
	 $fd = $2;
	 $pos = 0;
      }
   } elsif (/^close\((\d+)/ && $1==$fd) {
      $fd = undef;
   } elsif (/^lseek\((\d+), -?\d+,.*= (\d+)/ &&
	    $1==$fd && $2>=0) {
      $pos = $2;
   } elsif (/^lseek\((\d+),/ && $1==$fd) {
      die $_;
   } elsif (/^write\((\d+), ".*?"(\.\.\.)?, \d+\)\s*= (\d+)/ &&
	    $1==$fd && $3>=0) {
      my $nbytes = $3;
      printf "%d %d\n", $total, $pos;
      $pos += $nbytes;
      $total += $nbytes;
   } elsif (/^write\((\d+),/ && $1==$fd) {
      die $_;
   } elsif (/^read\((\d+), ".*?"(\.\.\.)?, \d+\)\s*= (\d+)/ &&
	    $1==$fd && $3>=0) {
      my $nbytes = $3;
      printf "%d %d\n", $total, $pos;
      $pos += $nbytes;
      $total += $nbytes;
   } elsif (/^read\((\d+),/ && $1==$fd) {
      die $_;
   }
}