Well here's my try. No temporary buffers. Recursive, but unrolling recursion seems to be easy enough. Maybe buggy :) 
use strict;
use warnings;

my @ary1 = qw( X0 X1 X2 Y0 Y1 Y2 );
my @ary2 = qw( X0 X1 Y0 Y1 Y2 Y3 );
my @ary3 = qw( X0 X1 X2 X3 Y0 Y1 );
my @ary4 = qw( X0 Y0 Y1 Y2 Y3 Y4 );
my @ary5 = qw( X0 X1 X2 X3 X4 Y0 );

my @buk1 = qw(
  X0 X1 X2 X3 X4 X5 X6 X7 X8 X9 Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7
);

my @buk2 = qw(
  X0 X1 X2 X3 X4 X5 X6 X7 Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9
);

swap( \@ary1, 3 );  # aref, offset of Y0
swap( \@ary2, 2 );
swap( \@ary3, 4 );
swap( \@ary4, 1 );
swap( \@ary5, 5 );
swap( \@buk1, 10 );
swap( \@buk2, 8 );

sub swap {
    my ( $ary, $offset ) = @_;
    my $swaps = do_swaps( $ary, 0, $offset, 0 );
    show( $ary, $swaps );
}

sub do_swaps {
    my ( $ary, $offset_x, $offset_y, $swaps ) = @_;

    return $swaps if $offset_y == @$ary;

    my ( $x, $y ) = ( $offset_x, $offset_y );
    my $temp;

    for ( $offset_x .. ( $offset_y - 1 ) ) {
        $y         = $offset_y if $y == @$ary;
        $temp      = $ary->[$x];
        $ary->[$x] = $ary->[$y];
        $ary->[$y] = $temp;
        $x += 1;
        $y += 1;

        $swaps += 1;
    }

    return do_swaps( $ary, $x, $y, $swaps );
}

sub show {
    my ( $ary, $swaps ) = @_;
    printf "%2d swaps => %s\n", $swaps, join ' ', @$ary;
}

[download]
Output: 
 3 swaps => Y0 Y1 Y2 X0 X1 X2
 4 swaps => Y0 Y1 Y2 Y3 X0 X1
 4 swaps => Y0 Y1 X0 X1 X2 X3
 5 swaps => Y0 Y1 Y2 Y3 Y4 X0
 5 swaps => Y0 X0 X1 X2 X3 X4
16 swaps => Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 X0 X1 X2 X3 X4 X5 X6 X7 X8 X9
16 swaps => Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 X0 X1 X2 X3 X4 X5 X6 X7

[download]

In reply to Re: [OT] Swapping buffers in place. by Anonymous Monk
in thread [OT] Swapping buffers in place. by BrowserUk

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