[Ffmpeg-devel] [PATCH] SSE counterpart of ff_imdct_calc_3dn2

Zuxy Meng zuxy.meng
Sun Aug 20 12:15:06 CEST 2006


Hi,

The patch is simply a re-write of Loren's recent work. fft-test shows
a speed-up around 18%~20% in my Pentium M 2G, not very exciting but
faster indeed. Please kindly take a review.

--
Zuxy
Beauty is truth,
While truth is beauty.
PGP KeyID: E8555ED6
-------------- next part --------------
Index: libavcodec/i386/fft_sse.c
===================================================================
--- libavcodec/i386/fft_sse.c	???????? 6032??
+++ libavcodec/i386/fft_sse.c	????????????
@@ -27,6 +27,9 @@
 static const int p1p1m1m1[4] __attribute__((aligned(16))) =
     { 0, 0, 1 << 31, 1 << 31 };
 
+static const int p1m1p1m1[4] __attribute__((aligned(16))) =
+    { 0, 1 << 31, 0, 1 << 31 };
+
 #if 0
 static void print_v4sf(const char *str, __m128 a)
 {
@@ -118,3 +121,98 @@
     } while (nblocks != 0);
 }
 
+void ff_imdct_calc_sse(MDCTContext *s, FFTSample *output,
+                       const FFTSample *input, FFTSample *tmp)
+{
+    long k, n8, n4, n2, n;
+    const uint16_t *revtab = s->fft.revtab;
+    const FFTSample *tcos = s->tcos;
+    const FFTSample *tsin = s->tsin;
+    const FFTSample *in1, *in2;
+    FFTComplex *z = (FFTComplex *)tmp;
+
+    n = 1 << s->nbits;
+    n2 = n >> 1;
+    n4 = n >> 2;
+    n8 = n >> 3;
+
+    asm volatile ("movaps %0, %%xmm7\n\t"::"m"(*p1m1p1m1));
+    
+    /* pre rotation */
+    in1 = input;
+    in2 = input + n2 - 4;
+    
+    /* Complex multiplication 
+       Two complex products per iteration, we could have 4 with 8 xmm
+       registers, 8 with 16 xmm registers.
+       Maybe we should unroll more.
+    */
+    for (k = 0; k < n4; k += 2) {
+        asm volatile (
+            "movaps          %0, %%xmm0 \n\t"   // xmm0 = r0 X  r1 X : in2
+            "movaps          %1, %%xmm3 \n\t"   // xmm3 = X  i1 X  i0: in1
+            "movlps          %2, %%xmm1 \n\t"   // xmm1 = X  X  R1 R0: tcos
+            "movlps          %3, %%xmm2 \n\t"   // xmm2 = X  X  I1 I0: tsin
+            "shufps $95, %%xmm0, %%xmm0 \n\t"   // xmm0 = r1 r1 r0 r0
+            "shufps $160,%%xmm3, %%xmm3 \n\t"   // xmm3 = i1 i1 i0 i0
+            "unpcklps    %%xmm2, %%xmm1 \n\t"   // xmm1 = I1 R1 I0 R0
+            "movaps      %%xmm1, %%xmm2 \n\t"   // xmm2 = I1 R1 I0 R0
+            "xorps       %%xmm7, %%xmm2 \n\t"   // xmm2 = -I1 R1 -I0 R0
+            "mulps       %%xmm1, %%xmm0 \n\t"   // xmm0 = rI rR rI rR
+            "shufps $177,%%xmm2, %%xmm2 \n\t"   // xmm2 = R1 -I1 R0 -I0
+            "mulps       %%xmm2, %%xmm3 \n\t"   // xmm3 = Ri -Ii Ri -Ii
+            "addps       %%xmm3, %%xmm0 \n\t"   // xmm0 = result
+            ::"m"(in2[-2*k]), "m"(in1[2*k]),
+              "m"(tcos[k]), "m"(tsin[k])
+        );
+        /* Should be in the same block, hack for gcc2.95 & gcc3 */
+        asm (
+            "movlps      %%xmm0, %0     \n\t"
+            "movhps      %%xmm0, %1     \n\t"
+            :"=m"(z[revtab[k]]), "=m"(z[revtab[k + 1]])
+        );
+    }
+
+    ff_fft_calc_sse(&s->fft, z);
+    
+    /* Not currently needed, added for safety */
+    asm volatile ("movaps %0, %%xmm7\n\t"::"m"(*p1m1p1m1));
+    
+    /* post rotation + reordering */
+    for (k = 0; k < n4; k += 2) {
+        asm (
+            "movaps          %0, %%xmm0 \n\t"   // xmm0 = i1 r1 i0 r0: z
+            "movlps          %1, %%xmm1 \n\t"   // xmm1 = X  X  R1 R0: tcos
+            "movaps      %%xmm0, %%xmm3 \n\t"   // xmm3 = i1 r1 i0 r0
+            "movlps          %2, %%xmm2 \n\t"   // xmm2 = X  X  I1 I0: tsin
+            "shufps $160,%%xmm0, %%xmm0 \n\t"   // xmm0 = r1 r1 r0 r0
+            "shufps $245,%%xmm3, %%xmm3 \n\t"   // xmm3 = i1 i1 i0 i0
+            "unpcklps    %%xmm2, %%xmm1 \n\t"   // xmm1 = I1 R1 I0 R0
+            "movaps      %%xmm1, %%xmm2 \n\t"   // xmm2 = I1 R1 I0 R0
+            "xorps       %%xmm7, %%xmm2 \n\t"   // xmm2 = -I1 R1 -I0 R0
+            "mulps       %%xmm1, %%xmm0 \n\t"   // xmm0 = rI rR rI rR
+            "shufps $177,%%xmm2, %%xmm2 \n\t"   // xmm2 = R1 -I1 R0 -I0
+            "mulps       %%xmm2, %%xmm3 \n\t"   // xmm3 = Ri -Ii Ri -Ii
+            "addps       %%xmm3, %%xmm0 \n\t"   // xmm0 = result
+            "movaps      %%xmm0, %0     \n\t"
+            :"+m"(z[k])
+            :"m"(tcos[k]), "m"(tsin[k])
+        );
+    }
+
+    z += n8;
+    /* XXX: Could be vectorized, but can't do better than the compiler */
+    for(k = 0; k < n8; k++) {
+        output[2*k] = -z[k].im;
+        output[n2 - 1 - 2*k] = z[k].im;
+
+        output[2*k + 1] = z[-k - 1].re;
+        output[n2 - 2 - 2*k] = -z[-k - 1].re;
+
+        output[n2 + 2*k] = -z[k].re;
+        output[n - 1 - 2*k] = -z[k].re;
+
+        output[n2 + 2*k + 1] = z[-k - 1].im;
+        output[n - 2 - 2*k] = z[-k - 1].im;
+    }
+}
Index: libavcodec/dsputil.h
===================================================================
--- libavcodec/dsputil.h	???????? 6032??
+++ libavcodec/dsputil.h	????????????
@@ -655,6 +655,8 @@
                 const FFTSample *input, FFTSample *tmp);
 void ff_imdct_calc_3dn2(MDCTContext *s, FFTSample *output,
                         const FFTSample *input, FFTSample *tmp);
+void ff_imdct_calc_sse(MDCTContext *s, FFTSample *output,
+                       const FFTSample *input, FFTSample *tmp);
 void ff_mdct_calc(MDCTContext *s, FFTSample *out,
                const FFTSample *input, FFTSample *tmp);
 void ff_mdct_end(MDCTContext *s);
Index: libavcodec/fft.c
===================================================================
--- libavcodec/fft.c	???????? 6032??
+++ libavcodec/fft.c	????????????
@@ -65,17 +65,18 @@
 
         if (has_vectors) {
 #if defined(HAVE_MMX)
-            if (has_vectors & MM_3DNOWEXT)
+            if (has_vectors & MM_3DNOWEXT) {
+                /* 3DNowEx for K7/K8 */
                 s->imdct_calc = ff_imdct_calc_3dn2;
-            if (has_vectors & MM_3DNOWEXT)
-                /* 3DNowEx for K7/K8 */
                 s->fft_calc = ff_fft_calc_3dn2;
-            else if (has_vectors & MM_3DNOW)
+            } else if (has_vectors & MM_3DNOW)
                 /* 3DNow! for K6-2/3 */
                 s->fft_calc = ff_fft_calc_3dn;
-            else if (has_vectors & MM_SSE)
+            else if (has_vectors & MM_SSE) {
                 /* SSE for P3/P4 */
                 s->fft_calc = ff_fft_calc_sse;
+                s->imdct_calc = ff_imdct_calc_sse;
+            }
 #else /* HAVE_MMX */
             if (has_vectors & MM_ALTIVEC)
                 s->fft_calc = ff_fft_calc_altivec;



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