Update to opus-HEAD-66611f1.

celt/mips/mdct_mipsr1.h

 /* Copyright (c) 2007-2008 CSIRO
    Copyright (c) 2007-2008 Xiph.Org Foundation
    Written by Jean-Marc Valin */
 /*
    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions
    are met:
 
    - Redistributions of source code must retain the above copyright
    notice, this list of conditions and the following disclaimer.
@@ skipping 20 matching lines @@
    plug in pretty much and FFT here.
 
    This replaces the Vorbis FFT (and uses the exact same API), which
    was a bit too messy and that was ending up duplicating code
    (might as well use the same FFT everywhere).
 
    The algorithm is similar to (and inspired from) Fabrice Bellard's
    MDCT implementation in FFMPEG, but has differences in signs, ordering
    and scaling in many places.
 */
+#ifndef __MDCT_MIPSR1_H__
+#define __MDCT_MIPSR1_H__
 
 #ifndef SKIP_CONFIG_H
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
 #endif
 
 #include "mdct.h"
 #include "kiss_fft.h"
 #include "_kiss_fft_guts.h"
 #include <math.h>
 #include "os_support.h"
 #include "mathops.h"
 #include "stack_alloc.h"
 
-#ifdef CUSTOM_MODES
-
-int clt_mdct_init(mdct_lookup *l,int N, int maxshift)
-{
-   int i;
-   int N4;
-   kiss_twiddle_scalar *trig;
-#if defined(FIXED_POINT)
-   int N2=N>>1;
-#endif
-   l->n = N;
-   N4 = N>>2;
-   l->maxshift = maxshift;
-   for (i=0;i<=maxshift;i++)
-   {
-      if (i==0)
-         l->kfft[i] = opus_fft_alloc(N>>2>>i, 0, 0);
-      else
-         l->kfft[i] = opus_fft_alloc_twiddles(N>>2>>i, 0, 0, l->kfft[0]);
-#ifndef ENABLE_TI_DSPLIB55
-      if (l->kfft[i]==NULL)
-         return 0;
-#endif
-   }
-   l->trig = trig = (kiss_twiddle_scalar*)opus_alloc((N4+1)*sizeof(kiss_twiddle_scalar));
-   if (l->trig==NULL)
-     return 0;
-   /* We have enough points that sine isn't necessary */
-#if defined(FIXED_POINT)
-   for (i=0;i<=N4;i++)
-      trig[i] = TRIG_UPSCALE*celt_cos_norm(DIV32(ADD32(SHL32(EXTEND32(i),17),N2),N));
-#else
-   for (i=0;i<=N4;i++)
-      trig[i] = (kiss_twiddle_scalar)cos(2*PI*i/N);
-#endif
-   return 1;
-}
-
-void clt_mdct_clear(mdct_lookup *l)
-{
-   int i;
-   for (i=0;i<=l->maxshift;i++)
-      opus_fft_free(l->kfft[i]);
-   opus_free((kiss_twiddle_scalar*)l->trig);
-}
-
-#endif /* CUSTOM_MODES */
-
 /* Forward MDCT trashes the input array */
+#define OVERRIDE_clt_mdct_forward
 void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * OPUS_RESTRICT out,
       const opus_val16 *window, int overlap, int shift, int stride)
 {
    int i;
    int N, N2, N4;
-   kiss_twiddle_scalar sine;
    VARDECL(kiss_fft_scalar, f);
-   VARDECL(kiss_fft_scalar, f2);
+   VARDECL(kiss_fft_cpx, f2);
+   const kiss_fft_state *st = l->kfft[shift];
+   const kiss_twiddle_scalar *trig;
+   opus_val16 scale;
+#ifdef FIXED_POINT
+   /* Allows us to scale with MULT16_32_Q16(), which is faster than
+      MULT16_32_Q15() on ARM. */
+   int scale_shift = st->scale_shift-1;
+#endif
    SAVE_STACK;
+   scale = st->scale;
+
    N = l->n;
-   N >>= shift;
+   trig = l->trig;
+   for (i=0;i<shift;i++)
+   {
+      N >>= 1;
+      trig += N;
+   }
    N2 = N>>1;
    N4 = N>>2;
+
    ALLOC(f, N2, kiss_fft_scalar);
-   ALLOC(f2, N2, kiss_fft_scalar);
-   /* sin(x) ~= x here */
-#ifdef FIXED_POINT
-   sine = TRIG_UPSCALE*(QCONST16(0.7853981f, 15)+N2)/N;
-#else
-   sine = (kiss_twiddle_scalar)2*PI*(.125f)/N;
-#endif
+   ALLOC(f2, N4, kiss_fft_cpx);
 
    /* Consider the input to be composed of four blocks: [a, b, c, d] */
    /* Window, shuffle, fold */
    {
       /* Temp pointers to make it really clear to the compiler what we're doing */
       const kiss_fft_scalar * OPUS_RESTRICT xp1 = in+(overlap>>1);
       const kiss_fft_scalar * OPUS_RESTRICT xp2 = in+N2-1+(overlap>>1);
       kiss_fft_scalar * OPUS_RESTRICT yp = f;
       const opus_val16 * OPUS_RESTRICT wp1 = window+(overlap>>1);
       const opus_val16 * OPUS_RESTRICT wp2 = window+(overlap>>1)-1;
       for(i=0;i<((overlap+3)>>2);i++)
       {
          /* Real part arranged as -d-cR, Imag part arranged as -b+aR*/
-         *yp++ = MULT16_32_Q15(*wp2, xp1[N2]) + MULT16_32_Q15(*wp1,*xp2);
-         *yp++ = MULT16_32_Q15(*wp1, *xp1)    - MULT16_32_Q15(*wp2, xp2[-N2]);
+          *yp++ = S_MUL_ADD(*wp2, xp1[N2],*wp1,*xp2);
+          *yp++ = S_MUL_SUB(*wp1, *xp1,*wp2, xp2[-N2]);
          xp1+=2;
          xp2-=2;
          wp1+=2;
          wp2-=2;
       }
       wp1 = window;
       wp2 = window+overlap-1;
       for(;i<N4-((overlap+3)>>2);i++)
       {
          /* Real part arranged as a-bR, Imag part arranged as -c-dR */
          *yp++ = *xp2;
          *yp++ = *xp1;
          xp1+=2;
          xp2-=2;
       }
       for(;i<N4;i++)
       {
          /* Real part arranged as a-bR, Imag part arranged as -c-dR */
-         *yp++ =  -MULT16_32_Q15(*wp1, xp1[-N2]) + MULT16_32_Q15(*wp2, *xp2);
-         *yp++ = MULT16_32_Q15(*wp2, *xp1)     + MULT16_32_Q15(*wp1, xp2[N2]);
+          *yp++ =  S_MUL_SUB(*wp2, *xp2, *wp1, xp1[-N2]);
+          *yp++ = S_MUL_ADD(*wp2, *xp1, *wp1, xp2[N2]);
          xp1+=2;
          xp2-=2;
          wp1+=2;
          wp2-=2;
       }
    }
    /* Pre-rotation */
    {
       kiss_fft_scalar * OPUS_RESTRICT yp = f;
-      const kiss_twiddle_scalar *t = &l->trig[0];
+      const kiss_twiddle_scalar *t = &trig[0];
       for(i=0;i<N4;i++)
       {
+         kiss_fft_cpx yc;
+         kiss_twiddle_scalar t0, t1;
          kiss_fft_scalar re, im, yr, yi;
-         re = yp[0];
-         im = yp[1];
-         yr = -S_MUL(re,t[i<<shift])  -  S_MUL(im,t[(N4-i)<<shift]);
-         yi = -S_MUL(im,t[i<<shift])  +  S_MUL(re,t[(N4-i)<<shift]);
-         /* works because the cos is nearly one */
-         *yp++ = yr + S_MUL(yi,sine);
-         *yp++ = yi - S_MUL(yr,sine);
+         t0 = t[i];
+         t1 = t[N4+i];
+         re = *yp++;
+         im = *yp++;
+
+         yr = S_MUL_SUB(re,t0,im,t1);
+         yi = S_MUL_ADD(im,t0,re,t1);
+
+         yc.r = yr;
+         yc.i = yi;
+         yc.r = PSHR32(MULT16_32_Q16(scale, yc.r), scale_shift);
+         yc.i = PSHR32(MULT16_32_Q16(scale, yc.i), scale_shift);
+         f2[st->bitrev[i]] = yc;
       }
    }
 
-   /* N/4 complex FFT, down-scales by 4/N */
-   opus_fft(l->kfft[shift], (kiss_fft_cpx *)f, (kiss_fft_cpx *)f2);
+   /* N/4 complex FFT, does not downscale anymore */
+   opus_fft_impl(st, f2);
 
    /* Post-rotate */
    {
       /* Temp pointers to make it really clear to the compiler what we're doing */
-      const kiss_fft_scalar * OPUS_RESTRICT fp = f2;
+      const kiss_fft_cpx * OPUS_RESTRICT fp = f2;
       kiss_fft_scalar * OPUS_RESTRICT yp1 = out;
       kiss_fft_scalar * OPUS_RESTRICT yp2 = out+stride*(N2-1);
-      const kiss_twiddle_scalar *t = &l->trig[0];
+      const kiss_twiddle_scalar *t = &trig[0];
       /* Temp pointers to make it really clear to the compiler what we're doing */
       for(i=0;i<N4;i++)
       {
          kiss_fft_scalar yr, yi;
-         yr = S_MUL(fp[1],t[(N4-i)<<shift]) + S_MUL(fp[0],t[i<<shift]);
-         yi = S_MUL(fp[0],t[(N4-i)<<shift]) - S_MUL(fp[1],t[i<<shift]);
-         /* works because the cos is nearly one */
-         *yp1 = yr - S_MUL(yi,sine);
-         *yp2 = yi + S_MUL(yr,sine);;
-         fp += 2;
+         yr = S_MUL_SUB(fp->i,t[N4+i] , fp->r,t[i]);
+         yi = S_MUL_ADD(fp->r,t[N4+i] ,fp->i,t[i]);
+         *yp1 = yr;
+         *yp2 = yi;
+         fp++;
          yp1 += 2*stride;
          yp2 -= 2*stride;
       }
    }
    RESTORE_STACK;
 }
 
+#define OVERRIDE_clt_mdct_backward
 void clt_mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * OPUS_RESTRICT out,
       const opus_val16 * OPUS_RESTRICT window, int overlap, int shift, int stride)
 {
    int i;
    int N, N2, N4;
-   kiss_twiddle_scalar sine;
-   VARDECL(kiss_fft_scalar, f2);
-   SAVE_STACK;
+   const kiss_twiddle_scalar *trig;
+
    N = l->n;
-   N >>= shift;
+   trig = l->trig;
+   for (i=0;i<shift;i++)
+   {
+      N >>= 1;
+      trig += N;
+   }
    N2 = N>>1;
    N4 = N>>2;
-   ALLOC(f2, N2, kiss_fft_scalar);
-   /* sin(x) ~= x here */
-#ifdef FIXED_POINT
-   sine = TRIG_UPSCALE*(QCONST16(0.7853981f, 15)+N2)/N;
-#else
-   sine = (kiss_twiddle_scalar)2*PI*(.125f)/N;
-#endif
 
    /* Pre-rotate */
    {
       /* Temp pointers to make it really clear to the compiler what we're doing */
       const kiss_fft_scalar * OPUS_RESTRICT xp1 = in;
       const kiss_fft_scalar * OPUS_RESTRICT xp2 = in+stride*(N2-1);
-      kiss_fft_scalar * OPUS_RESTRICT yp = f2;
-      const kiss_twiddle_scalar *t = &l->trig[0];
+      kiss_fft_scalar * OPUS_RESTRICT yp = out+(overlap>>1);
+      const kiss_twiddle_scalar * OPUS_RESTRICT t = &trig[0];
+      const opus_int16 * OPUS_RESTRICT bitrev = l->kfft[shift]->bitrev;
       for(i=0;i<N4;i++)
       {
+         int rev;
          kiss_fft_scalar yr, yi;
-         yr = -S_MUL(*xp2, t[i<<shift]) + S_MUL(*xp1,t[(N4-i)<<shift]);
-         yi =  -S_MUL(*xp2, t[(N4-i)<<shift]) - S_MUL(*xp1,t[i<<shift]);
-         /* works because the cos is nearly one */
-         *yp++ = yr - S_MUL(yi,sine);
-         *yp++ = yi + S_MUL(yr,sine);
+         rev = *bitrev++;
+         yr = S_MUL_ADD(*xp2, t[i] , *xp1, t[N4+i]);
+         yi = S_MUL_SUB(*xp1, t[i] , *xp2, t[N4+i]);
+         /* We swap real and imag because we use an FFT instead of an IFFT. */
+         yp[2*rev+1] = yr;
+         yp[2*rev] = yi;
+         /* Storing the pre-rotation directly in the bitrev order. */
          xp1+=2*stride;
          xp2-=2*stride;
       }
    }
 
-   /* Inverse N/4 complex FFT. This one should *not* downscale even in fixed-point */
-   opus_ifft(l->kfft[shift], (kiss_fft_cpx *)f2, (kiss_fft_cpx *)(out+(overlap>>1)));
+   opus_fft_impl(l->kfft[shift], (kiss_fft_cpx*)(out+(overlap>>1)));
 
    /* Post-rotate and de-shuffle from both ends of the buffer at once to make
       it in-place. */
    {
       kiss_fft_scalar * OPUS_RESTRICT yp0 = out+(overlap>>1);
       kiss_fft_scalar * OPUS_RESTRICT yp1 = out+(overlap>>1)+N2-2;
-      const kiss_twiddle_scalar *t = &l->trig[0];
+      const kiss_twiddle_scalar *t = &trig[0];
       /* Loop to (N4+1)>>1 to handle odd N4. When N4 is odd, the
          middle pair will be computed twice. */
       for(i=0;i<(N4+1)>>1;i++)
       {
          kiss_fft_scalar re, im, yr, yi;
          kiss_twiddle_scalar t0, t1;
-         re = yp0[0];
-         im = yp0[1];
-         t0 = t[i<<shift];
-         t1 = t[(N4-i)<<shift];
+         /* We swap real and imag because we're using an FFT instead of an IFFT. */
+         re = yp0[1];
+         im = yp0[0];
+         t0 = t[i];
+         t1 = t[N4+i];
          /* We'd scale up by 2 here, but instead it's done when mixing the windows */
-         yr = S_MUL(re,t0) - S_MUL(im,t1);
-         yi = S_MUL(im,t0) + S_MUL(re,t1);
-         re = yp1[0];
-         im = yp1[1];
-         /* works because the cos is nearly one */
-         yp0[0] = -(yr - S_MUL(yi,sine));
-         yp1[1] = yi + S_MUL(yr,sine);
+         yr = S_MUL_ADD(re,t0 , im,t1);
+         yi = S_MUL_SUB(re,t1 , im,t0);
+         /* We swap real and imag because we're using an FFT instead of an IFFT. */
+         re = yp1[1];
+         im = yp1[0];
+         yp0[0] = yr;
+         yp1[1] = yi;
 
-         t0 = t[(N4-i-1)<<shift];
-         t1 = t[(i+1)<<shift];
+         t0 = t[(N4-i-1)];
+         t1 = t[(N2-i-1)];
          /* We'd scale up by 2 here, but instead it's done when mixing the windows */
-         yr = S_MUL(re,t0) - S_MUL(im,t1);
-         yi = S_MUL(im,t0) + S_MUL(re,t1);
-         /* works because the cos is nearly one */
-         yp1[0] = -(yr - S_MUL(yi,sine));
-         yp0[1] = yi + S_MUL(yr,sine);
+         yr = S_MUL_ADD(re,t0,im,t1);
+         yi = S_MUL_SUB(re,t1,im,t0);
+         yp1[0] = yr;
+         yp0[1] = yi;
          yp0 += 2;
          yp1 -= 2;
       }
    }
 
    /* Mirror on both sides for TDAC */
    {
       kiss_fft_scalar * OPUS_RESTRICT xp1 = out+overlap-1;
       kiss_fft_scalar * OPUS_RESTRICT yp1 = out;
       const opus_val16 * OPUS_RESTRICT wp1 = window;
       const opus_val16 * OPUS_RESTRICT wp2 = window+overlap-1;
 
       for(i = 0; i < overlap/2; i++)
       {
          kiss_fft_scalar x1, x2;
          x1 = *xp1;
          x2 = *yp1;
          *yp1++ = MULT16_32_Q15(*wp2, x2) - MULT16_32_Q15(*wp1, x1);
          *xp1-- = MULT16_32_Q15(*wp1, x2) + MULT16_32_Q15(*wp2, x1);
          wp1++;
          wp2--;
       }
    }
-   RESTORE_STACK;
 }
+#endif /* __MDCT_MIPSR1_H__ */