fft altivec by Romain Dolbeau - simplified patch, test it on PPC with fft-test and wma decoding

Originally committed as revision 1417 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/Makefile

@@ -84,7 +84,8 @@ endif
 
 ifeq ($(TARGET_ALTIVEC),yes)
 CFLAGS += -faltivec
-OBJS += ppc/dsputil_altivec.o ppc/mpegvideo_altivec.o ppc/idct_altivec.o
+OBJS += ppc/dsputil_altivec.o ppc/mpegvideo_altivec.o ppc/idct_altivec.o \
+        ppc/fft_altivec.o
 endif
 
 SRCS := $(OBJS:.o=.c) $(ASM_OBJS:.o=.S)

libavcodec/dsputil.h

@@ -265,6 +265,8 @@ int fft_init(FFTContext *s, int nbits, int inverse);
 void fft_permute(FFTContext *s, FFTComplex *z);
 void fft_calc_c(FFTContext *s, FFTComplex *z);
 void fft_calc_sse(FFTContext *s, FFTComplex *z);
+void fft_calc_altivec(FFTContext *s, FFTComplex *z);
+
 static inline void fft_calc(FFTContext *s, FFTComplex *z)
 {
     s->fft_calc(s, z);

libavcodec/fft.c

@@ -51,34 +51,48 @@ int fft_init(FFTContext *s, int nbits, int inverse)
     s->exptab1 = NULL;
 
     /* compute constant table for HAVE_SSE version */
-#if defined(HAVE_MMX) && defined(HAVE_BUILTIN_VECTOR)
-    if (mm_support() & MM_SSE) {
-        int np, nblocks, np2, l;
-        FFTComplex *q;
-        
-        np = 1 << nbits;
-        nblocks = np >> 3;
-        np2 = np >> 1;
-        s->exptab1 = av_malloc(np * 2 * sizeof(FFTComplex));
-        if (!s->exptab1)
-            goto fail;
-        q = s->exptab1;
-        do {
-            for(l = 0; l < np2; l += 2 * nblocks) {
-                *q++ = s->exptab[l];
-                *q++ = s->exptab[l + nblocks];
-
-                q->re = -s->exptab[l].im;
-                q->im = s->exptab[l].re;
-                q++;
-                q->re = -s->exptab[l + nblocks].im;
-                q->im = s->exptab[l + nblocks].re;
-                q++;
-            }
-            nblocks = nblocks >> 1;
-        } while (nblocks != 0);
-        av_freep(&s->exptab);
-        s->fft_calc = fft_calc_sse;
+#if (defined(HAVE_MMX) && defined(HAVE_BUILTIN_VECTOR)) || defined(HAVE_ALTIVEC)
+    {
+        int has_vectors;
+
+#if defined(HAVE_MMX)
+        has_vectors = mm_support() & MM_SSE;
+#else
+        /* XXX: should also use mm_support() ? */
+        has_vectors = has_altivec() & MM_ALTIVEC;
+#endif
+        if (has_vectors) {
+            int np, nblocks, np2, l;
+            FFTComplex *q;
+            
+            np = 1 << nbits;
+            nblocks = np >> 3;
+            np2 = np >> 1;
+            s->exptab1 = av_malloc(np * 2 * sizeof(FFTComplex));
+            if (!s->exptab1)
+                goto fail;
+            q = s->exptab1;
+            do {
+                for(l = 0; l < np2; l += 2 * nblocks) {
+                    *q++ = s->exptab[l];
+                    *q++ = s->exptab[l + nblocks];
+
+                    q->re = -s->exptab[l].im;
+                    q->im = s->exptab[l].re;
+                    q++;
+                    q->re = -s->exptab[l + nblocks].im;
+                    q->im = s->exptab[l + nblocks].re;
+                    q++;
+                }
+                nblocks = nblocks >> 1;
+            } while (nblocks != 0);
+            av_freep(&s->exptab);
+#if defined(HAVE_MMX)
+            s->fft_calc = fft_calc_sse;
+#else
+            s->fft_calc = fft_calc_altivec;
+#endif
+        }
     }
 #endif
 

libavcodec/ppc/fft_altivec.c

+/*
+ * FFT/IFFT transforms
+ * AltiVec-enabled
+ * Copyright (c) 2002 Romain Dolbeau <romain@dolbeau.org>
+ * Based on code Copyright (c) 2002 Fabrice Bellard.
+ *
+ * This library 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 of the License, or (at your option) any later version.
+ *
+ * This library 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 this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#include "../dsputil.h"
+
+#include "dsputil_altivec.h"
+
+// used to build registers permutation vectors (vcprm)
+// the 's' are for words in the _s_econd vector
+#define WORD_0 0x00,0x01,0x02,0x03
+#define WORD_1 0x04,0x05,0x06,0x07
+#define WORD_2 0x08,0x09,0x0a,0x0b
+#define WORD_3 0x0c,0x0d,0x0e,0x0f
+#define WORD_s0 0x10,0x11,0x12,0x13
+#define WORD_s1 0x14,0x15,0x16,0x17
+#define WORD_s2 0x18,0x19,0x1a,0x1b
+#define WORD_s3 0x1c,0x1d,0x1e,0x1f
+
+#define vcprm(a,b,c,d) (const vector unsigned char)(WORD_ ## a, WORD_ ## b, WORD_ ## c, WORD_ ## d)
+
+// vcprmle is used to keep the same index as in the SSE version.
+// it's the same as vcprm, with the index inversed
+// ('le' is Little Endian)
+#define vcprmle(a,b,c,d) vcprm(d,c,b,a)
+
+// used to build inverse/identity vectors (vcii)
+// n is _n_egative, p is _p_ositive
+#define FLOAT_n -1.
+#define FLOAT_p 1.
+
+#define vcii(a,b,c,d) (const vector float)(FLOAT_ ## a, FLOAT_ ## b, FLOAT_ ## c, FLOAT_ ## d)
+
+/**
+ * Do a complex FFT with the parameters defined in fft_init(). The
+ * input data must be permuted before with s->revtab table. No
+ * 1.0/sqrt(n) normalization is done.
+ * AltiVec-enabled
+ * This code assumes that the 'z' pointer is 16 bytes-aligned
+ * It also assumes all FFTComplex are 8 bytes-aligned pair of float
+ * The code is exactly the same as the SSE version, except
+ * that successive MUL + ADD/SUB have been fusionned into
+ * fused multiply-add ('vec_madd' in altivec)
+ *
+ * To test this code you can use fft-test in libavcodec ; use
+ * the following line in libavcodec to compile (MacOS X):
+ * #####
+ * gcc -I. -Ippc -no-cpp-precomp -pipe -O3 -fomit-frame-pointer -mdynamic-no-pic -Wall
+ *     -faltivec -DARCH_POWERPC -DHAVE_ALTIVEC -DCONFIG_DARWIN fft-test.c fft.c
+ *     ppc/fft_altivec.c ppc/dsputil_altivec.c mdct.c -DHAVE_LRINTF -o fft-test
+ * #####
+ */
+void fft_calc_altivec(FFTContext *s, FFTComplex *z)
+{
+    register const vector float vczero = (vector float)( 0., 0., 0., 0.);
+    
+    int ln = s->nbits;
+    int	j, np, np2;
+    int	nblocks, nloops;
+    register FFTComplex *p, *q;
+    FFTComplex *cptr, *cptr1;
+    int k;
+
+    np = 1 << ln;
+
+    {
+        vector float *r, a, b, a1, c1, c2;
+
+        r = (vector float *)&z[0];
+
+        c1 = vcii(p,p,n,n);
+        
+        if (s->inverse)
+            {
+                c2 = vcii(p,p,n,p);
+            }
+        else
+            {
+                c2 = vcii(p,p,p,n);
+            }
+        
+        j = (np >> 2);
+        do {
+            a = vec_ld(0, r);
+            a1 = vec_ld(sizeof(vector float), r);
+            
+            b = vec_perm(a,a,vcprmle(1,0,3,2));
+            a = vec_madd(a,c1,b);
+            /* do the pass 0 butterfly */
+            
+            b = vec_perm(a1,a1,vcprmle(1,0,3,2));
+            b = vec_madd(a1,c1,b);
+            /* do the pass 0 butterfly */
+            
+            /* multiply third by -i */
+            b = vec_perm(b,b,vcprmle(2,3,1,0));
+            
+            /* do the pass 1 butterfly */
+            vec_st(vec_madd(b,c2,a), 0, r);
+            vec_st(vec_nmsub(b,c2,a), sizeof(vector float), r);
+            
+            r += 2;
+        } while (--j != 0);
+    }
+    /* pass 2 .. ln-1 */
+
+    nblocks = np >> 3;
+    nloops = 1 << 2;
+    np2 = np >> 1;
+
+    cptr1 = s->exptab1;
+    do {
+        p = z;
+        q = z + nloops;
+        j = nblocks;
+        do {
+            cptr = cptr1;
+            k = nloops >> 1;
+            do {
+                vector float a,b,c,t1;
+
+                a = vec_ld(0, (float*)p);
+                b = vec_ld(0, (float*)q);
+                
+                /* complex mul */
+                c = vec_ld(0, (float*)cptr);
+                /*  cre*re cim*re */
+                t1 = vec_madd(c, vec_perm(b,b,vcprmle(2,2,0,0)),vczero);
+                c = vec_ld(sizeof(vector float), (float*)cptr);
+                /*  -cim*im cre*im */
+                b = vec_madd(c, vec_perm(b,b,vcprmle(3,3,1,1)),t1);
+                
+                /* butterfly */
+                vec_st(vec_add(a,b), 0, (float*)p);
+                vec_st(vec_sub(a,b), 0, (float*)q);
+                
+                p += 2;
+                q += 2;
+                cptr += 4;
+            } while (--k);
+            
+            p += nloops;
+            q += nloops;
+        } while (--j);
+        cptr1 += nloops * 2;
+        nblocks = nblocks >> 1;
+        nloops = nloops << 1;
+    } while (nblocks != 0);
+}
+