[FFmpeg-devel] [PATCH] hardcoded ff_cos tables

[Reimar Döffinger]

On Tue, Oct 13, 2009 at 02:20:49PM +0200, Diego Biurrun wrote:
> On Tue, Oct 13, 2009 at 01:05:04PM +0200, Reimar D?ffinger wrote:
> > --- tools/costablegen.c	(revision 0)
> > +++ tools/costablegen.c	(revision 0)
> > @@ -0,0 +1,25 @@
> > +#include <stdio.h>
> > +#include "libavcodec/dsputil.h"
> 
> Please add license headers even for simple files.

As long as you don't expect me to add one to the generate cos_table.h

> > --- libavcodec/dsputil.h	(revision 20222)
> > +++ libavcodec/dsputil.h	(working copy)
> > @@ -742,7 +742,11 @@
> >  
> > -extern FFTSample* const ff_cos_tabs[13];
> > +extern
> > +#if CONFIG_HARDCODED_TABLES
> > +const
> > +#endif
> > +FFTSample* const ff_cos_tabs[13];
> > -extern FFTSample* const ff_cos_tabs[13];
> 
> I think the following is more readable:
> 
>   #if CONFIG_HARDCODED_TABLES
>   extern const FFTSample* const ff_cos_tabs[13];
>   #else
>   extern FFTSample* const ff_cos_tabs[13];
>   #endif

Probably.
-------------- next part --------------
Index: tools/costablegen.c
===================================================================
--- tools/costablegen.c	(revision 0)
+++ tools/costablegen.c	(revision 0)
@@ -0,0 +1,47 @@
+/*
+ * Generate a header file for hardcoded ff_cos_* tables
+ *
+ * Copyright (c) 2009 Reimar D?ffinger <Reimar.Doeffinger at gmx.de>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+#include <stdio.h>
+#include "libavcodec/dsputil.h"
+#undef fprintf
+#define BITS 16
+#define FLOATFMT "%.18e"
+int main(void)
+{
+    int i, j;
+    FILE *table = fopen("libavcodec/cos_tables.h", "w");
+    FFTContext ctx;
+    ctx.split_radix = 1;
+    ff_fft_init(&ctx, BITS, 0);
+    fprintf(table, "/* This file was generated by tools/costablegen */\n");
+    fprintf(table, "#include \"dsputil.h\"\n");
+    for (i = 4; i <= BITS; i++) {
+        int m = 1 << i;
+        fprintf(table, "const FFTSample ff_cos_%i[] = {\n   ", m);
+        for (j = 0; j < m/2 - 1; j++) {
+            fprintf(table, " "FLOATFMT",", ff_cos_tabs[i-4][j]);
+            if ((j & 3) == 3)
+                fprintf(table, "\n   ");
+        }
+        fprintf(table, " "FLOATFMT"\n};\n", ff_cos_tabs[i-4][m/2-1]);
+    }
+    return 0;
+}
Index: libavcodec/fft.c
===================================================================
--- libavcodec/fft.c	(revision 20223)
+++ libavcodec/fft.c	(working copy)
@@ -28,6 +28,7 @@
 
 #include "dsputil.h"
 
+#if !CONFIG_HARDCODED_TABLES
 /* cos(2*pi*x/n) for 0<=x<=n/4, followed by its reverse */
 DECLARE_ALIGNED_16(FFTSample, ff_cos_16[8]);
 DECLARE_ALIGNED_16(FFTSample, ff_cos_32[16]);
@@ -42,6 +43,10 @@
 DECLARE_ALIGNED_16(FFTSample, ff_cos_16384[8192]);
 DECLARE_ALIGNED_16(FFTSample, ff_cos_32768[16384]);
 DECLARE_ALIGNED_16(FFTSample, ff_cos_65536[32768]);
+#else
+#include "cos_tables.h"
+const
+#endif
 FFTSample * const ff_cos_tabs[] = {
     ff_cos_16, ff_cos_32, ff_cos_64, ff_cos_128, ff_cos_256, ff_cos_512, ff_cos_1024,
     ff_cos_2048, ff_cos_4096, ff_cos_8192, ff_cos_16384, ff_cos_32768, ff_cos_65536,
@@ -93,6 +98,7 @@
     if (HAVE_MMX)     ff_fft_init_mmx(s);
 
     if (s->split_radix) {
+#if !CONFIG_HARDCODED_TABLES
         for(j=4; j<=nbits; j++) {
             int m = 1<<j;
             double freq = 2*M_PI/m;
@@ -102,6 +108,7 @@
             for(i=1; i<m/4; i++)
                 tab[m/2-i] = tab[i];
         }
+#endif
         for(i=0; i<n; i++)
             s->revtab[-split_radix_permutation(i, n, s->inverse) & (n-1)] = i;
         s->tmp_buf = av_malloc(n * sizeof(FFTComplex));
Index: libavcodec/dsputil.h
===================================================================
--- libavcodec/dsputil.h	(revision 20222)
+++ libavcodec/dsputil.h	(working copy)
@@ -742,7 +742,11 @@
 #define FF_MDCT_PERM_INTERLEAVE 1
 } FFTContext;
 
+#if CONFIG_HARDCODED_TABLES
+extern const FFTSample* const ff_cos_tabs[13];
+#else
 extern FFTSample* const ff_cos_tabs[13];
+#endif
 
 /**
  * Sets up a complex FFT.