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/*
* Discrete Cosine Tansform (DCT) for subband synthesis
*
* -funroll-loops (for gcc) will remove the loops for better performance
* using loops in the source-code enhances readabillity
*/
/*
* TODO: write an optimized version for the down-sampling modes
* (in these modes the bands 16-31 (2:1) or 8-31 (4:1) are zero
*/
#include "mpg123.h"
void dct64(real *out0,real *out1,real *samples)
{
real bufs[64];
{
register int i,j;
register real *b1,*b2,*bs,*costab;
b1 = samples;
bs = bufs;
costab = pnts[0]+16;
b2 = b1 + 32;
for(i=15;i>=0;i--)
*bs++ = (*b1++ + *--b2);
for(i=15;i>=0;i--)
*bs++ = REAL_MUL((*--b2 - *b1++), *--costab);
b1 = bufs;
costab = pnts[1]+8;
b2 = b1 + 16;
{
for(i=7;i>=0;i--)
*bs++ = (*b1++ + *--b2);
for(i=7;i>=0;i--)
*bs++ = REAL_MUL((*--b2 - *b1++), *--costab);
b2 += 32;
costab += 8;
for(i=7;i>=0;i--)
*bs++ = (*b1++ + *--b2);
for(i=7;i>=0;i--)
*bs++ = REAL_MUL((*b1++ - *--b2), *--costab);
b2 += 32;
}
bs = bufs;
costab = pnts[2];
b2 = b1 + 8;
for(j=2;j;j--)
{
for(i=3;i>=0;i--)
*bs++ = (*b1++ + *--b2);
for(i=3;i>=0;i--)
*bs++ = REAL_MUL((*--b2 - *b1++), costab[i]);
b2 += 16;
for(i=3;i>=0;i--)
*bs++ = (*b1++ + *--b2);
for(i=3;i>=0;i--)
*bs++ = REAL_MUL((*b1++ - *--b2), costab[i]);
b2 += 16;
}
b1 = bufs;
costab = pnts[3];
b2 = b1 + 4;
for(j=4;j;j--)
{
*bs++ = (*b1++ + *--b2);
*bs++ = (*b1++ + *--b2);
*bs++ = REAL_MUL((*--b2 - *b1++), costab[1]);
*bs++ = REAL_MUL((*--b2 - *b1++), costab[0]);
b2 += 8;
*bs++ = (*b1++ + *--b2);
*bs++ = (*b1++ + *--b2);
*bs++ = REAL_MUL((*b1++ - *--b2), costab[1]);
*bs++ = REAL_MUL((*b1++ - *--b2), costab[0]);
b2 += 8;
}
bs = bufs;
costab = pnts[4];
for(j=8;j;j--)
{
real v0,v1;
v0=*b1++; v1 = *b1++;
*bs++ = (v0 + v1);
*bs++ = REAL_MUL((v0 - v1), (*costab));
v0=*b1++; v1 = *b1++;
*bs++ = (v0 + v1);
*bs++ = REAL_MUL((v1 - v0), (*costab));
}
}
{
register real *b1;
register int i;
for(b1=bufs,i=8;i;i--,b1+=4)
b1[2] += b1[3];
for(b1=bufs,i=4;i;i--,b1+=8)
{
b1[4] += b1[6];
b1[6] += b1[5];
b1[5] += b1[7];
}
for(b1=bufs,i=2;i;i--,b1+=16)
{
b1[8] += b1[12];
b1[12] += b1[10];
b1[10] += b1[14];
b1[14] += b1[9];
b1[9] += b1[13];
b1[13] += b1[11];
b1[11] += b1[15];
}
}
out0[0x10*16] = bufs[0];
out0[0x10*15] = bufs[16+0] + bufs[16+8];
out0[0x10*14] = bufs[8];
out0[0x10*13] = bufs[16+8] + bufs[16+4];
out0[0x10*12] = bufs[4];
out0[0x10*11] = bufs[16+4] + bufs[16+12];
out0[0x10*10] = bufs[12];
out0[0x10* 9] = bufs[16+12] + bufs[16+2];
out0[0x10* 8] = bufs[2];
out0[0x10* 7] = bufs[16+2] + bufs[16+10];
out0[0x10* 6] = bufs[10];
out0[0x10* 5] = bufs[16+10] + bufs[16+6];
out0[0x10* 4] = bufs[6];
out0[0x10* 3] = bufs[16+6] + bufs[16+14];
out0[0x10* 2] = bufs[14];
out0[0x10* 1] = bufs[16+14] + bufs[16+1];
out0[0x10* 0] = bufs[1];
out1[0x10* 0] = bufs[1];
out1[0x10* 1] = bufs[16+1] + bufs[16+9];
out1[0x10* 2] = bufs[9];
out1[0x10* 3] = bufs[16+9] + bufs[16+5];
out1[0x10* 4] = bufs[5];
out1[0x10* 5] = bufs[16+5] + bufs[16+13];
out1[0x10* 6] = bufs[13];
out1[0x10* 7] = bufs[16+13] + bufs[16+3];
out1[0x10* 8] = bufs[3];
out1[0x10* 9] = bufs[16+3] + bufs[16+11];
out1[0x10*10] = bufs[11];
out1[0x10*11] = bufs[16+11] + bufs[16+7];
out1[0x10*12] = bufs[7];
out1[0x10*13] = bufs[16+7] + bufs[16+15];
out1[0x10*14] = bufs[15];
out1[0x10*15] = bufs[16+15];
}
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