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Tidy up for ROLI
author Geogaddi\David <d.m.ronan@qmul.ac.uk>
date Tue, 17 May 2016 18:50:19 +0100
parents 636c989477e7
children
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--- a/Lib/fftw-3.2.1/doc/html/.svn/text-base/SIMD-alignment-and-fftw_005fmalloc.html.svn-base	Wed May 04 11:02:59 2016 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
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-<html lang="en">
-<head>
-<title>SIMD alignment and fftw_malloc - FFTW 3.2.1</title>
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-<hr>
-</div>
-
-<h4 class="subsection">3.1.1 SIMD alignment and fftw_malloc</h4>
-
-<p>SIMD, which stands for &ldquo;Single Instruction Multiple Data,&rdquo; is a set of
-special operations supported by some processors to perform a single
-operation on several numbers (usually 2 or 4) simultaneously.  SIMD
-floating-point instructions are available on several popular CPUs:
-SSE/SSE2 (single/double precision) on Pentium III and higher and on
-AMD64, AltiVec (single precision) on some PowerPCs (Apple G4 and
-higher), and MIPS Paired Single.  FFTW can be compiled to support the
-SIMD instructions on any of these systems. 
-<a name="index-SIMD-102"></a><a name="index-SSE-103"></a><a name="index-SSE2-104"></a><a name="index-AltiVec-105"></a><a name="index-MIPS-PS-106"></a><a name="index-precision-107"></a>
-A program linking to an FFTW library compiled with SIMD support can
-obtain a nonnegligible speedup for most complex and r2c/c2r
-transforms.  In order to obtain this speedup, however, the arrays of
-complex (or real) data passed to FFTW must be specially aligned in
-memory (typically 16-byte aligned), and often this alignment is more
-stringent than that provided by the usual <code>malloc</code> (etc.) 
-allocation routines.
-
-   <p><a name="index-portability-108"></a>In order to guarantee proper alignment for SIMD, therefore, in case
-your program is ever linked against a SIMD-using FFTW, we recommend
-allocating your transform data with <code>fftw_malloc</code> and
-de-allocating it with <code>fftw_free</code>. 
-<a name="index-fftw_005fmalloc-109"></a><a name="index-fftw_005ffree-110"></a>These have exactly the same interface and behavior as
-<code>malloc</code>/<code>free</code>, except that for a SIMD FFTW they ensure
-that the returned pointer has the necessary alignment (by calling
-<code>memalign</code> or its equivalent on your OS).
-
-   <p>You are not <em>required</em> to use <code>fftw_malloc</code>.  You can
-allocate your data in any way that you like, from <code>malloc</code> to
-<code>new</code> (in C++) to a fixed-size array declaration.  If the array
-happens not to be properly aligned, FFTW will not use the SIMD
-extensions. 
-<a name="index-C_002b_002b-111"></a>
-<!-- =========> -->
-
-   </body></html>
-