[FFmpeg-devel] [PATCH] hardcoded ff_cos tables
Reimar Döffinger
Reimar.Doeffinger
Wed Oct 14 11:14:40 CEST 2009
On Wed, Oct 14, 2009 at 09:56:26AM +0100, M?ns Rullg?rd wrote:
> Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:
>
> > On Tue, Oct 13, 2009 at 02:41:33PM +0200, Reimar D?ffinger wrote:
> >> On Tue, Oct 13, 2009 at 01:29:39PM +0100, M?ns Rullg?rd wrote:
> >> > Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:
> >> > > attached patch allows hardcoding the ff_cos tables so they are in
> >> > > .rodata instead of .bss.
> >> > > Not included is the cos_tables.h file as generated by costablegen.c
> >> > > since it is > 1.7 MB.
> >> > > Which I admit is a bit of an issue, including this file directly into
> >> > > SVN is not all that great, but it would be the simplest solution by far...
> >> >
> >> > We could generate the tables at build time.
> >>
> >> Not with this patch, since that reuses the libavcodec/fft.c code to
> >> generate them, which will be disabled with hardcoded tables enabled.
> >> It is of course possible to just duplicate the code from
> >> libavcodec/fft.c, but that is not that beautiful either...
> >
> > Ok, so here is the version using that approach.
> > I moved the code to libavcodec, I think it works better for handling the
> > dependencies and also is better for projects that import libavcodec
> > directly.
> >
> > Index: libavcodec/Makefile
> > ===================================================================
> > --- libavcodec/Makefile (revision 20231)
> > +++ libavcodec/Makefile (working copy)
> > @@ -27,7 +27,7 @@
> > # parts needed for many different codecs
> > OBJS-$(CONFIG_AANDCT) += aandcttab.o
> > OBJS-$(CONFIG_ENCODERS) += faandct.o jfdctfst.o jfdctint.o
> > -OBJS-$(CONFIG_FFT) += fft.o
> > +OBJS-$(CONFIG_FFT) += fft.o cos_tables.h
> > OBJS-$(CONFIG_GOLOMB) += golomb.o
> > OBJS-$(CONFIG_MDCT) += mdct.o
> > OBJS-$(CONFIG_RDFT) += rdft.o
>
> WTF?
>
> > @@ -574,3 +574,5 @@
> > include $(SUBDIR)../subdir.mak
> >
> > $(SUBDIR)dct-test$(EXESUF): $(SUBDIR)dctref.o
> > +cos_tables.h: costablegen
> > + ./costablegen > cos_tables.h
>
> This doesn't work:
>
> - It fails if building from the top level like most people do.
> - It fails on systems like mswindows with non-empty EXESUF.
> - If fails if cross-compiling.
>
> To fix this:
>
> - Use $(SUBDIR) as in the line before.
> - Use $(HOSTCC) and friends as in the rules for tests/videogen etc.
Yes, I noticed half of this by now, but I am sure I missed another half
still. Have a look at this.
-------------- next part --------------
Index: libavcodec/dsputil.h
===================================================================
--- libavcodec/dsputil.h (revision 20231)
+++ 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.
Index: libavcodec/Makefile
===================================================================
--- libavcodec/Makefile (revision 20231)
+++ libavcodec/Makefile (working copy)
@@ -574,3 +574,12 @@
include $(SUBDIR)../subdir.mak
$(SUBDIR)dct-test$(EXESUF): $(SUBDIR)dctref.o
+
+$(SUBDIR)costablegen$(HOSTEXESUF): $(SUBDIR)costablegen.c
+ $(HOSTCC) $(HOSTCFLAGS) $(HOSTLDFLAGS) -o $@ $< $(HOSTLIBS)
+
+$(SUBDIR)cos_tables.h: $(SUBDIR)costablegen$(HOSTEXESUF)
+ ./$< > $@
+
+clean::
+ rm -f $(SUBDIR)cos_tables.h
Index: libavcodec/costablegen.c
===================================================================
--- libavcodec/costablegen.c (revision 0)
+++ libavcodec/costablegen.c (revision 0)
@@ -0,0 +1,49 @@
+/*
+ * 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 "libavutil/mathematics.h"
+#undef fprintf
+
+#define BITS 16
+#define FLOATFMT "%.18e"
+
+int main(void)
+{
+ int i, j;
+ FILE *table = stdout;
+ fprintf(table, "/* This file was generated by libavcodec/costablegen */\n");
+ fprintf(table, "#include \"dsputil.h\"\n");
+ for (i = 4; i <= BITS; i++) {
+ int m = 1 << i;
+ double freq = 2*M_PI/m;
+ fprintf(table, "const FFTSample ff_cos_%i[] = {\n ", m);
+ for (j = 0; j < m/2 - 1; j++) {
+ int idx = j > m/4 ? m/2 - j : j;
+ fprintf(table, " "FLOATFMT",", cos(idx*freq));
+ if ((j & 3) == 3)
+ fprintf(table, "\n ");
+ }
+ fprintf(table, " "FLOATFMT"\n};\n", cos(freq));
+ }
+ return 0;
+}
Index: libavcodec/fft.c
===================================================================
--- libavcodec/fft.c (revision 20231)
+++ 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));
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