gcc/testsuite/gcc.dg/vmx/fft.c

   1 /* { dg-do compile } */
   2 #include <altivec.h>
   3
   4 inline void
   5 transpose4x4(vector float *matrix)
   6 {
   7   vector float v0, v1, v2, v3;
   8
   9   v0 = vec_mergeh(matrix[0], matrix[2]);
  10   v1 = vec_mergel(matrix[0], matrix[2]);
  11   v2 = vec_mergeh(matrix[1], matrix[3]);
  12   v3 = vec_mergel(matrix[1], matrix[3]);
  13
  14   matrix[0] = vec_mergeh(v0, v2);
  15   matrix[1] = vec_mergel(v0, v2);
  16   matrix[2] = vec_mergeh(v1, v3);
  17   matrix[3] = vec_mergel(v1, v3);
  18 }
  19
  20 void
  21 vec_ifft64(vector float *x0, vector float *x1)
  22 {
  23   int i;
  24   vector float real[4], imag[4];
  25   vector float c0r, c1r, c2r, c3r, c0i, c1i, c2i, c3i;
  26   vector float d0r, d1r, d2r, d3r, d0i, d1i, d2i, d3i;
  27
  28   /*
  29    *  N=64
  30    *
  31    *  Stage 1: t=1 => k = 0, j = 0..15
  32    *  ================================
  33    *  for j = 0:15
  34    *    c0 = x0(j+0*16);
  35    *    c1 = x0(j+1*16);
  36    *    c2 = x0(j+2*16);
  37    *    c3 = x0(j+3*16);
  38    *
  39    *    d0 = c0 + c2;
  40    *    d1 = c0 - c2;
  41    *    d2 = c1 + c3;
  42    *    d3 = i*(c1 - c3);
  43    *
  44    *    x1(4j+0) = d0 + d2;
  45    *    x1(4j+1) = d1 + d3;
  46    *    x1(4j+2) = d0 - d2;
  47    *    x1(4j+3) = d1 - d3;
  48    *  end
  49    ******************************************************/
  50
  51   for (i=0; i < 4; i++)
  52     {
  53       c0r = x0[i];
  54       c1r = x0[i+4];
  55       c2r = x0[i+8];
  56       c3r = x0[i+12];
  57
  58       c0i = x0[i+16];
  59       c1i = x0[i+20];
  60       c2i = x0[i+24];
  61       c3i = x0[i+28];
  62
  63       d0r = vec_add(c0r, c2r);
  64       d1r = vec_sub(c0r, c2r);
  65       d2r = vec_add(c1r, c3r);
  66       d3r = vec_sub(c3i, c1i);
  67
  68       d0i = vec_add(c0i, c2i);
  69       d1i = vec_sub(c0i, c2i);
  70       d2i = vec_add(c1i, c3i);
  71       d3i = vec_sub(c1r, c3r);
  72
  73       /* Calculate real{x1} */
  74       real[0] = vec_add(d0r, d2r);
  75       real[1] = vec_add(d1r, d3r);
  76       real[2] = vec_sub(d0r, d2r);
  77       real[3] = vec_sub(d1r, d3r);
  78
  79       transpose4x4(real);
  80
  81       /* Calculate imag{x1} */
  82       imag[0] = vec_add(d0i, d2i);
  83       imag[1] = vec_add(d1i, d3i);
  84       imag[2] = vec_sub(d0i, d2i);
  85       imag[3] = vec_sub(d1i, d3i);
  86
  87       transpose4x4(imag);
  88
  89       x1[4*i]   = real[0];
  90       x1[4*i+1] = real[1];
  91       x1[4*i+2] = real[2];
  92       x1[4*i+3] = real[3];
  93
  94       x1[4*i+16] = imag[0];
  95       x1[4*i+17] = imag[1];
  96       x1[4*i+18] = imag[2];
  97       x1[4*i+19] = imag[3];
  98     }
  99 }