PPC: Altivec IMDCT

Patch by Loren Merritt

Originally committed as revision 23959 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/ppc/fft_altivec.c

@@ -37,6 +37,7 @@
 // that involves an extra level of indirection on some PPC ABIs.
 extern void *ff_fft_dispatch_altivec[2][15];
 
+#if HAVE_GNU_AS
 // Convert from simd order to C order.
 static void swizzle(vec_f *z, int n)
 {
@@ -50,7 +51,7 @@ static void swizzle(vec_f *z, int n)
     }
 }
 
-static void ff_fft_calc_altivec(FFTContext *s, FFTComplex *z)
+static av_always_inline void fft_dispatch(FFTContext *s, FFTComplex *z, int do_swizzle)
 {
     register vec_f  v14 __asm__("v14") = {0,0,0,0};
     register vec_f  v15 __asm__("v15") = *(const vec_f*)ff_cos_16;
@@ -76,19 +77,128 @@ static void ff_fft_calc_altivec(FFTContext *s, FFTComplex *z)
         "subi "r(1)","r(1) ",%1 \n"
         "bctrl                  \n"
         "addi "r(1)","r(1) ",%1 \n"
-        ::"r"(ff_fft_dispatch_altivec[1][s->nbits-2]), "i"(12*sizeof(void*)),
+        ::"r"(ff_fft_dispatch_altivec[do_swizzle][s->nbits-2]), "i"(12*sizeof(void*)),
           "r"(zarg), "r"(cos_tabs),
           "v"(v14),"v"(v15),"v"(v16),"v"(v17),"v"(v18),"v"(v19),"v"(v20),"v"(v21),
           "v"(v22),"v"(v23),"v"(v24),"v"(v25),"v"(v26),"v"(v27),"v"(v28),"v"(v29)
         : "lr","ctr","r0","r4","r5","r6","r7","r8","r9","r10","r11",
           "v0","v1","v2","v3","v4","v5","v6","v7","v8","v9","v10","v11","v12","v13"
     );
-    if (s->nbits <= 4)
+    if (do_swizzle && s->nbits <= 4)
         swizzle((vec_f*)z, 1<<s->nbits);
 }
 
+static void ff_fft_calc_altivec(FFTContext *s, FFTComplex *z)
+{
+    fft_dispatch(s, z, 1);
+}
+
+static void ff_imdct_half_altivec(FFTContext *s, FFTSample *output, const FFTSample *input)
+{
+    int j, k;
+    int n = 1 << s->mdct_bits;
+    int n4 = n >> 2;
+    int n8 = n >> 3;
+    int n32 = n >> 5;
+    const uint16_t *revtabj = s->revtab;
+    const uint16_t *revtabk = s->revtab+n4;
+    const vec_f *tcos = (const vec_f*)(s->tcos+n8);
+    const vec_f *tsin = (const vec_f*)(s->tsin+n8);
+    const vec_f *pin = (const vec_f*)(input+n4);
+    vec_f *pout = (vec_f*)(output+n4);
+
+    /* pre rotation */
+    k = n32-1;
+    do {
+        vec_f cos,sin,cos0,sin0,cos1,sin1,re,im,r0,i0,r1,i1,a,b,c,d;
+#define CMULA(p,o0,o1,o2,o3)\
+        a = pin[ k*2+p];                       /* { z[k].re,    z[k].im,    z[k+1].re,  z[k+1].im  } */\
+        b = pin[-k*2-p-1];                     /* { z[-k-2].re, z[-k-2].im, z[-k-1].re, z[-k-1].im } */\
+        re = vec_perm(a, b, vcprm(0,2,s0,s2)); /* { z[k].re,    z[k+1].re,  z[-k-2].re, z[-k-1].re } */\
+        im = vec_perm(a, b, vcprm(s3,s1,3,1)); /* { z[-k-1].im, z[-k-2].im, z[k+1].im,  z[k].im    } */\
+        cos = vec_perm(cos0, cos1, vcprm(o0,o1,s##o2,s##o3)); /* { cos[k], cos[k+1], cos[-k-2], cos[-k-1] } */\
+        sin = vec_perm(sin0, sin1, vcprm(o0,o1,s##o2,s##o3));\
+        r##p = im*cos - re*sin;\
+        i##p = re*cos + im*sin;
+#define STORE2(v,dst)\
+        j = dst;\
+        vec_ste(v, 0, output+j*2);\
+        vec_ste(v, 4, output+j*2);
+#define STORE8(p)\
+        a = vec_perm(r##p, i##p, vcprm(0,s0,0,s0));\
+        b = vec_perm(r##p, i##p, vcprm(1,s1,1,s1));\
+        c = vec_perm(r##p, i##p, vcprm(2,s2,2,s2));\
+        d = vec_perm(r##p, i##p, vcprm(3,s3,3,s3));\
+        STORE2(a, revtabk[ p*2-4]);\
+        STORE2(b, revtabk[ p*2-3]);\
+        STORE2(c, revtabj[-p*2+2]);\
+        STORE2(d, revtabj[-p*2+3]);
+
+        cos0 = tcos[k];
+        sin0 = tsin[k];
+        cos1 = tcos[-k-1];
+        sin1 = tsin[-k-1];
+        CMULA(0, 0,1,2,3);
+        CMULA(1, 2,3,0,1);
+        STORE8(0);
+        STORE8(1);
+        revtabj += 4;
+        revtabk -= 4;
+        k--;
+    } while(k >= 0);
+
+    fft_dispatch(s, (FFTComplex*)output, 0);
+
+    /* post rotation + reordering */
+    j = -n32;
+    k = n32-1;
+    do {
+        vec_f cos,sin,re,im,a,b,c,d;
+#define CMULB(d0,d1,o)\
+        re = pout[o*2];\
+        im = pout[o*2+1];\
+        cos = tcos[o];\
+        sin = tsin[o];\
+        d0 = im*sin - re*cos;\
+        d1 = re*sin + im*cos;
+
+        CMULB(a,b,j);
+        CMULB(c,d,k);
+        pout[2*j]   = vec_perm(a, d, vcprm(0,s3,1,s2));
+        pout[2*j+1] = vec_perm(a, d, vcprm(2,s1,3,s0));
+        pout[2*k]   = vec_perm(c, b, vcprm(0,s3,1,s2));
+        pout[2*k+1] = vec_perm(c, b, vcprm(2,s1,3,s0));
+        j++;
+        k--;
+    } while(k >= 0);
+}
+
+static void ff_imdct_calc_altivec(FFTContext *s, FFTSample *output, const FFTSample *input)
+{
+    int k;
+    int n = 1 << s->mdct_bits;
+    int n4 = n >> 2;
+    int n16 = n >> 4;
+    vec_u32 sign = {1<<31,1<<31,1<<31,1<<31};
+    vec_u32 *p0 = (vec_u32*)(output+n4);
+    vec_u32 *p1 = (vec_u32*)(output+n4*3);
+
+    ff_imdct_half_altivec(s, output+n4, input);
+
+    for (k = 0; k < n16; k++) {
+        vec_u32 a = p0[k] ^ sign;
+        vec_u32 b = p1[-k-1];
+        p0[-k-1] = vec_perm(a, a, vcprm(3,2,1,0));
+        p1[k]    = vec_perm(b, b, vcprm(3,2,1,0));
+    }
+}
+#endif /* HAVE_GNU_AS */
+
 av_cold void ff_fft_init_altivec(FFTContext *s)
 {
-    if (HAVE_GNU_AS)
+    if (HAVE_GNU_AS) {
         s->fft_calc = ff_fft_calc_altivec;
+        s->imdct_calc = ff_imdct_calc_altivec;
+        s->imdct_half = ff_imdct_half_altivec;
+    }
 }