#!/usr/bin/perl -w

use strict;

my $cols_per_row = 6;                   # columns per row

undef $/;
my $table = <DATA>;
1 while(chomp);

my @table = ( [] );
my $cols_got = 0;

while ($table ne '') {
  $table =~ s{^,?(["']?)((?:[^\1]|\1(?=\1))+?)?(\1)[,\n]}{}s;
  if (++$cols_got > $cols_per_row) {
    push @table, [];
    $cols_got = 1;
  }
  push @{$table[-1]}, $2;
}

foreach my $row (@table) {
  foreach my $col (@$row) {
    $col =~ s/(["']){2}/$1/g;
    $col =~ s/\n/\\n/g;
  }
  print join('|', @$row), "\n";
}

__DATA__
12345,"foobar",45.67,"""this"" is a field with
embedded newlines",4567,"frumpy"
12345,"foobar",45.67,"this is a ""field"" with
embedded newlines",4567,"frumpy"