#!/usr/bin/perl
#  use for example as            twopage.pl <s.ps >out.ps
$flag = 0;                      # We have not yet found a page
$even = 0;                      # First page is an odd page
$page = 1;                      # Start at page #1
$pages = 1;                     # Allow %%Pages comment
while (<>) {
    if (/^%%Pages:/ && $pages) {
        print "%%Pages: (atend)\n";
        $pages = 0;
    } elsif (/^%%Page:/) {      # We have found a page
        if ($flag) {
            print "restore\n";  # restore if it isn't the first
        }
        $flag = 1;
        if ($even) {            # Translate for even pages
            print "save\n";     # gsave
            print "504 426 translate\n";
            $even = 0;
            $page++;
        } else {                # Translate for odd pages
            printf("%%%%Page: %d %d\n", $page, $page);
            print "save /showpage {} def\n";
            print "504 30 translate\n";
            $even = 1;
        }                       # Code to rotate and shrink
        print "90 rotate .5 .5 scale\n";
    } elsif (/^%%Trail/) {      # Cleanup if a %%Trailer is found
        if ($flag) {
            print "restore\n";
        }
        print $_;
        printf("%%%%Pages: %d\n", $page);
        $flag = 0;
    } elsif (/^%%EOF/) {        # Cleanup if an %%EOF is found
        if ($flag) {
            print "restore\n";
        }
        print $_;
        $flag = 0;
    } else {
        print;
    }
}