use Encode;

my $cp1252_str = join('',
  chr(0x80), chr(0x81), chr(0x91), chr(0x92),
  chr(0x93), chr(0x94), chr(0x95), chr(0x96),
);

my $utf8_str = decode( 'cp1252', $cp1252_str );

# update: you can now remove "unmapped" byte values this way:

$utf8_str =~ tr/\x{fffd}//d;


##</code><code>##

open( INPUT, "<:encoding(cp1252)", $filename ) or die $!;

# or, if the file handle is already open (e.g. STDIN):
#  binmode FILEHANDLE, ":encoding(cp1252)";

while (<INPUT>) {
    # $_ contains utf8 data...
}