X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;f=lib%2FScalar%2FVec%2FUtil.pm;h=dd8b1cbcea3b3cdb30da08a3098a114c9701b838;hb=856caa5792565f48b11a5dc86856519b649eaffb;hp=12d049c26364708fa28e59b337745040da53e5e4;hpb=01ef742d705c0bd6577139d1ee8a2808101336da;p=perl%2Fmodules%2FScalar-Vec-Util.git

diff --git a/lib/Scalar/Vec/Util.pm b/lib/Scalar/Vec/Util.pm
index 12d049c..dd8b1cb 100644
--- a/lib/Scalar/Vec/Util.pm
+++ b/lib/Scalar/Vec/Util.pm
@@ -132,14 +132,48 @@ sub vshift {
   $left = 0;
   $bits = -$bits;
  }
- $bits    = $length if $bits > $length;
+ if ($bits < $length) {
+  $length -= $bits;
+  if ($left) {
+   vcopy($_[0], $start, $_[0], $start + $bits, $length);
+   vfill($_[0], $start, $bits, $insert) if defined $insert;
+  } else {
+   vcopy($_[0], $start + $bits, $_[0], $start, $length);
+   vfill($_[0], $start + $length, $bits, $insert) if defined $insert;
+  }
+ } else {
+  vfill($_[0], $start, $length, $insert) if defined $insert;
+ }
+}
+
+=head2 C<< vrot $v, $start, $length, $bits >>
+
+In the area starting at C<$start> and of length C<$length> in C<$v>, rotates bits C<abs $bits> positions left if C<< $bits > 0 >> and right otherwise.
+Bits outside of the specified area are left untouched.
+Currently allocates an extra buffer of size C<O($bits)>.
+
+=cut
+
+sub vrot {
+ my ($start, $length, $bits) = @_[1 .. 3];
+ return unless $length and $bits;
+ my $left = 1;
+ if ($bits < 0) {
+  $left = 0;
+  $bits = -$bits;
+ }
+ $bits %= $length;
+ return unless $bits;
  $length -= $bits;
+ my $buf = '';
  if ($left) {
-  vcopy($_[0], $start, $_[0], $start + $bits, $length);
-  vfill($_[0], $start, $bits, $insert) if defined $insert;
+  vcopy($_[0], $start + $length, $buf,  0,              $bits);
+  vcopy($_[0], $start,           $_[0], $start + $bits, $length);
+  vcopy($buf,  0,                $_[0], $start,         $bits);
  } else {
-  vcopy($_[0], $start + $bits, $_[0], $start, $length);
-  vfill($_[0], $start + $length, $bits, $insert) if defined $insert;
+  vcopy($_[0], $start,           $buf,  0,                $bits);
+  vcopy($_[0], $start + $bits,   $_[0], $start,           $length);
+  vcopy($buf,  0,                $_[0], $start + $length, $bits);
  }
 }
 
@@ -163,7 +197,7 @@ sub veq_pp {
 
 =head1 EXPORT
 
-The functions L</vfill>, L</vcopy>, L</vshift> and L</veq> are only exported on request.
+The functions L</vfill>, L</vcopy>, L</vshift>, L</vrot> and L</veq> are only exported on request.
 All of them are exported by the tags C<':funcs'> and C<':all'>.
 
 The constants L</SVU_PP> and L</SVU_SIZE> are also only exported on request.
@@ -175,7 +209,7 @@ use base qw/Exporter/;
 
 our @EXPORT         = ();
 our %EXPORT_TAGS    = (
- 'funcs'  => [ qw/vfill vcopy vshift veq/ ],
+ 'funcs'  => [ qw/vfill vcopy vshift vrot veq/ ],
  'consts' => [ qw/SVU_PP SVU_SIZE/ ]
 );
 our @EXPORT_OK      = map { @$_ } values %EXPORT_TAGS;