/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id: $
 *
 * Copyright (C) 2010 Dave Hooper
 *
 * ARM optimisations for ffmpeg's fft (used in fft-ffmpeg.c)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/

#ifdef CPU_ARM

/* Start off with optimised variants of the butterflies that work
   nicely on arm */
/* 1.  where y and a share the same variable/register */
#define BF_OPT(x,y,a,b) {\
    y = a + b;\
    x = y - (b<<1);\
}

/* 2.  where y and b share the same variable/register */
#define BF_OPT2(x,y,a,b) {\
    x = a - b;\
    y = x + (b<<1);\
}

/* 3.  where y and b share the same variable/register (but y=(-b)) */
#define BF_OPT2_REV(x,y,a,b) {\
    x = a + b;\
    y = x - (b<<1);\
}

/* standard BUTTERFLIES package.  Note, we actually manually inline this
   in all the TRANSFORM macros below anyway */
#define FFT_FFMPEG_INCL_OPTIMISED_BUTTERFLIES
#define BUTTERFLIES(a0,a1,a2,a3) {\
    {\
        BF_OPT(t1, t5, t5, t1);\
        BF_OPT(t6, t2, t2, t6);\
        BF_OPT(a2.re, a0.re, a0.re, t5);\
        BF_OPT(a2.im, a0.im, a0.im, t2);\
        BF_OPT(a3.re, a1.re, a1.re, t6);\
        BF_OPT(a3.im, a1.im, a1.im, t1);\
    }\
}

#define FFT_FFMPEG_INCL_OPTIMISED_TRANSFORM

/* on ARM, all the TRANSFORM_etc inlines use the following registers:
   r5,r6,r7,r8,r9,r10,r4,r12
   
   inputs are: z, n, STEP
   
   NOTE THAT THESE MACROS ACTUALLY CHANGE z INPUT INPLACE-
   so sequential actions, z += n*3, z -= n*2 etc etc matter
*/
   

#define TRANSFORM_POST_STORE( z, n ) {\
    /*{*/\
    /*   BF_OPT(t1, t5, t5, t1);*/\
    /*    BF_OPT(t6, t2, t2, t6);*/\
    /*    BF_OPT(a2.re, a0.re, a0.re, t5);*/\
    /*    BF_OPT(a2.im, a0.im, a0.im, t2);*/\
    /*    BF_OPT(a3.re, a1.re, a1.re, t6);*/\
    /*    BF_OPT(a3.im, a1.im, a1.im, t1);*/\
    /*}*/\
    z -= n*3;\
    /* r_re = my_z[0]; r_im = my_z[1]; */\
    {\
        register FFTSample rt0temp asm("r4");\
        asm volatile( "ldmia %[my_z], {%[r_re],%[r_im]}\n\t":[r_re] "=r" (r_re), [r_im] "=r" (r_im):[my_z] "r" (z));\
        BF_OPT(rt0temp, r_re, r_re, t5);\
        BF_OPT(t2,      r_im, r_im, t2);\
        /* my_z[0] = r_re; my_z[1] = r_im; */\
        asm volatile( "stmia %[my_z], {%[r_re],%[r_im]}\n\t"::[my_z] "r" (z), [r_re] "r" (r_re), [r_im] "r" (r_im));\
        z += n;\
        /* r_re = my_z[0]; r_im = my_z[1]; */\
        asm volatile( "ldmia %[my_z], {%[r_re],%[r_im]}\n\t":[r_re] "=r" (r_re), [r_im] "=r" (r_im):[my_z] "r" (z));\
        BF_OPT(t5, r_re, r_re, t6);\
        BF_OPT(t6, r_im, r_im, t1);\
        /* my_z[0] = r_re; my_z[1] = r_im; */\
        asm volatile( "stmia %[my_z], {%[r_re],%[r_im]}\n\t"::[my_z] "r" (z), [r_re] "r" (r_re), [r_im] "r" (r_im));\
        z += n;\
        /* my_z[0] = rt0temp; my_z[1] = t2; */\
        asm volatile( "stmia %[my_z], {%[rt0temp],%[t2]}\n\t"::[my_z] "r" (z), [rt0temp] "r" (rt0temp), [t2] "r" (t2));\
        z += n;\
    }\
    /* my_z[0] = t5; my_z[1] = t6; */\
    asm volatile( "stmia %[my_z], {%[t5],%[t6]}\n\t"::[my_z] "r" (z), [t5] "r" (t5), [t6] "r" (t6));\
    z -= n*3;\
}

#define TRANSFORM( z, n, wre_arg, wim_arg )\
{\
    FFTSample wre = wre_arg, wim = wim_arg;\
    register FFTSample t1 asm("r5"),t2 asm("r6"),t5 asm("r7"),t6 asm("r8"),r_re asm("r9"),r_im asm("r10");\
    z += n*2; /* z[o2] */\
    asm volatile( "ldmia %[my_z], {%[r_re],%[r_im]}\n\t":[r_re] "=r" (r_re), [r_im] "=r" (r_im):[my_z] "r" (z));\
    XPROD31_R(r_re, r_im, wre, wim, t1,t2);\
    \
    z += n; /* z[o3] */\
    asm volatile( "ldmia %[my_z], {%[r_re],%[r_im]}\n\t":[r_re] "=r" (r_re), [r_im] "=r" (r_im):[my_z] "r" (z));\
    XNPROD31_R(r_re, r_im, wre, wim, t5,t6);\
    \
    BF_OPT(t1, t5, t5, t1);\
    BF_OPT(t6, t2, t2, t6);\
    TRANSFORM_POST_STORE( z, n );\
}

#define TRANSFORM_W01( z, n, w )\
{\
    register FFTSample t1 asm("r5"),t2 asm("r6"),t5 asm("r7"),t6 asm("r8"),r_re asm("r9"),r_im asm("r10");\
    \
    {\
        register FFTSample wre asm("r4"),wim asm("r12");\
        asm volatile( "ldmia %[w], {%[wre], %[wim]}\n\t":[wre] "=r" (wre), [wim] "=r" (wim):[w] "r" (w));\
        z += n*2; /* z[o2] -- 2n * 2 since complex numbers */\
        asm volatile( "ldmia %[my_z], {%[r_re],%[r_im]}\n\t":[r_re] "=r" (r_re), [r_im] "=r" (r_im):[my_z] "r" (z));\
        XPROD31_R(r_re, r_im, wre, wim, t1,t2);\
\
        z += n; /* z[o3] */\
        asm volatile( "ldmia %[my_z], {%[r_re],%[r_im]}\n\t":[r_re] "=r" (r_re), [r_im] "=r" (r_im):[my_z] "r" (z));\
        XNPROD31_R(r_re, r_im, wre, wim, t5,t6);\
    }\
    \
    BF_OPT(t1, t5, t5, t1);\
    BF_OPT(t6, t2, t2, t6);\
    TRANSFORM_POST_STORE( z, n );\
}

//static inline void TRANSFORM_W10(int32_t * z, unsigned int n, const int32_t * w)
#define TRANSFORM_W10( z, n, w )\
{\
    register FFTSample t1 asm("r5"),t2 asm("r6"),t5 asm("r7"),t6 asm("r8"),r_re asm("r9"),r_im asm("r10");\
    \
    {\
        register FFTSample wim asm("r4"),wre asm("r12");\
        asm volatile( "ldmia %[w], {%[wim], %[wre]}\n\t":[wim] "=r" (wim), [wre] "=r" (wre):[w] "r" (w));\
        z += n*2; /* z[o2] -- 2n * 2 since complex numbers */\
        asm volatile( "ldmia %[my_z], {%[r_re],%[r_im]}\n\t":[r_re] "=r" (r_re), [r_im] "=r" (r_im):[my_z] "r" (z));\
        XPROD31_R(r_re, r_im, wre, wim, t1,t2);\
\
        z += n; /* z[o3] */\
        asm volatile( "ldmia %[my_z], {%[r_re],%[r_im]}\n\t":[r_re] "=r" (r_re), [r_im] "=r" (r_im):[my_z] "r" (z));\
        XNPROD31_R(r_re, r_im, wre, wim, t5,t6);\
    }\
    \
    BF_OPT(t1, t5, t5, t1);\
    BF_OPT(t6, t2, t2, t6);\
    TRANSFORM_POST_STORE( z, n );\
}

#define TRANSFORM_EQUAL( z, n )\
{\
    register FFTSample t1 asm("r5"),t2 asm("r6"),t5 asm("r7"),t6 asm("r8"),r_re asm("r9"),r_im asm("r10");\
\
    z += n*2; /* z[o2] -- 2n * 2 since complex numbers */\
    asm volatile( "ldmia %[my_z], {%[t5],%[t6]}\n\t":[t5] "=r" (t5), [t6] "=r" (t6):[my_z] "r" (z));\
    z += n; /* z[o3] */\
    asm volatile( "ldmia %[my_z], {%[r_re],%[r_im]}\n\t":[r_re] "=r" (r_re), [r_im] "=r" (r_im):[my_z] "r" (z));\
\
/**/\
/*t2 = MULT32(cPI2_8, t5);*/\
/*t1 = MULT31(cPI2_8, t6);*/\
/*t6 = MULT31(cPI2_8, r_re);*/\
/*t5 = MULT32(cPI2_8, r_im);*/\
\  
/*t1 = ( t1 + (t2<<1) );*/\
/*t2 = ( t1 - (t2<<2) );*/\
/*t6 = ( t6 + (t5<<1) );*/\
/*t5 = ( t6 - (t5<<2) );*/\
/**/\
    t2   = MULT31(cPI2_8, t5);\
    t6   = MULT31(cPI2_8, t6);\
    r_re = MULT31(cPI2_8, r_re);\
    t5   = MULT31(cPI2_8, r_im);\
    \
    t1 = ( t6 + t2 );\
    t2 = ( t6 - t2 );\
    t6 = ( r_re + t5 );\
    t5 = ( r_re - t5 );\
    \
    BF_OPT(t1, t5, t5, t1);\
    BF_OPT(t6, t2, t2, t6);\
    TRANSFORM_POST_STORE( z, n );\
}

#define TRANSFORM_ZERO( z,n )\
{\
    register FFTSample t1 asm("r5"),t2 asm("r6"),t5 asm("r7"),t6 asm("r8"),r_re asm("r9"),r_im asm("r10");\
\
    z += n*2; /* z[o2] -- 2n * 2 since complex numbers */\
    asm volatile( "ldmia %[my_z], {%[t1],%[t2]}\n\t":[t1] "=r" (t1), [t2] "=r" (t2):[my_z] "r" (z));\
    z += n; /* z[o3] */\
    asm volatile( "ldmia %[my_z], {%[t5],%[t6]}\n\t":[t5] "=r" (t5), [t6] "=r" (t6):[my_z] "r" (z));\
\
    BF_OPT(t1, t5, t5, t1);\
    BF_OPT(t6, t2, t2, t6);\
    TRANSFORM_POST_STORE( z, n );\
}

#define FFT_FFMPEG_INCL_OPTIMISED_FFT4
#define fft4(z_arg)\
{\
    /* input[0..7] -> output[0..7] */\
    fixed32 * m = (fixed32 *) ( ( z_arg ) );\
    /* load r1=z[0],r2=z[1],...,r8=z[7] */\
    asm volatile(\
      "ldmia %[z], {r1-r8}\n\t"\
      "add r1,r1,r3\n\t"         /* r1 :=t1 */\
      "sub r3,r1,r3, lsl #1\n\t" /* r3 :=t3 */\
      "sub r7,r7,r5\n\t"         /* r10:=t8 */\
      "add r5,r7,r5, lsl #1\n\t" /* r5 :=t6 */\
      \
      "add r1,r1,r5\n\t"                 /* r1 = o[0] */\
      "sub r5,r1,r5, lsl #1\n\t"         /* r5 = o[4] */\
      \
      "add r2,r2,r4\n\t"         /* r2 :=t2 */\
      "sub r4,r2,r4, lsl #1\n\t" /* r9 :=t4 */\
      \
      "add r12,r6,r8\n\t"        /* r10:=t5 */\
      "sub r6,r6,r8\n\t"         /* r6 :=t7 */\
      \
      "sub r8,r4,r7\n\t"                 /* r8 = o[7]*/ \
      "add r4,r4,r7\n\t"                 /* r4 = o[3]*/ \
      "sub r7,r3,r6\n\t"                 /* r7 = o[6]*/ \
      "add r3,r3,r6\n\t"                 /* r3 = o[2]*/ \
      "sub r6,r2,r12\n\t"                /* r6 = o[5]*/ \
      "add r2,r2,r12\n\t"                /* r2 = o[1]*/ \
      \
      "stmia %[z], {r1-r8}\n\t"\
      : /* outputs */\
      : /* inputs */ [z] "r" (m)\
      : /* clobbers */\
      "r1","r2","r3","r4","r5","r6","r7","r8","r12","memory"\
   );\
}


#define FFT_FFMPEG_INCL_OPTIMISED_FFT8
        /* The chunk of asm below is equivalent to the following:
        
        // first load in z[4].re thru z[7].im into local registers
        // ...
        BF_OPT2_REV(z[4].re, z[5].re, z[4].re, z[5].re); // x=a+b; y=x-(b<<1)
        BF_OPT2_REV(z[4].im, z[5].im, z[4].im, z[5].im);
        BF_REV     (temp, z[7].re, z[6].re, z[7].re);  // x=a+b; y=a-b;
        BF_REV     (z[6].re, z[7].im, z[6].im, z[7].im);
        // save z[7].re and z[7].im as those are complete now
        // z[5].re and z[5].im are also complete now but save these later on
        
        BF(z[6].im, z[4].re, temp, z[4].re);        // x=a-b; y=a+b
        BF_OPT(z[6].re, z[4].im, z[4].im, z[6].re); // y=a+b; x=y-(b<<1)
        // now load z[2].re and z[2].im
        // ...        
        BF_OPT(z[6].re, z[2].re, z[2].re, z[6].re); // y=a+b; x=y-(b<<1)
        BF_OPT(z[6].im, z[2].im, z[2].im, z[6].im); // y=a+b; x=y-(b<<1)
        // Now save z[6].re and z[6].im, along with z[5].re and z[5].im
        // for efficiency.  Also save z[2].re and z[2].im.
        // Now load z[0].re and z[0].im
        // ...
        
        BF_OPT(z[4].re, z[0].re, z[0].re, z[4].re); // y=a+b; x=y-(b<<1)
        BF_OPT(z[4].im, z[0].im, z[0].im, z[4].im); // y=a+b; x=y-(b<<1)
        // Finally save out z[4].re, z[4].im, z[0].re and z[0].im
        // ...
        */
static inline void fft8( FFTComplex * z )
{
    fft4(z);
    {
        FFTSample temp;
        fixed32 * m4 = (fixed32 *)(&(z[4].re));
        
        asm volatile(
            "add %[z_ptr], %[z_ptr], #16\n\t"  /* point to &z[2].re */
            /* read in z[4].re thru z[7].im */
            "ldmia %[z4_ptr]!, {r1,r2,r3,r4,r5,r6,r7,r8}\n\t"
            /* (now points one word past &z[7].im) */
            "add r1,r1,r3\n\t"
            "sub r3,r1,r3,lsl #1\n\t"
            "add r2,r2,r4\n\t"
            "sub r4,r2,r4,lsl #1\n\t"
            "add %[temp],r5,r7\n\t"
            "sub r7,r5,r7\n\t"
            "add r5,r6,r8\n\t"
            "sub r8,r6,r8\n\t"
            
            "stmdb %[z4_ptr]!, {r7,r8}\n\t" /* write z[7].re,z[7].im  straight away */
                                            /* Note, registers r7 & r8 now free */
            
            "sub r6,%[temp],r1\n\t"
            "add r1,%[temp],r1\n\t"
            "add r2,r2,r5\n\t"
            "sub r5,r2,r5,lsl #1\n\t"
            
            "ldmia %[z_ptr],{r7,r8}\n\t"  /* load z[2].re and z[2].im */
            "add r7,r7,r5\n\t"
            "sub r5,r7,r5,lsl #1\n\t"
            "add r8,r8,r6\n\t"
            "sub r6,r8,r6,lsl #1\n\t"
            
            /* write out z[5].re, z[5].im, z[6].re, z[6].im in one go*/
            "stmdb %[z4_ptr]!, {r3,r4,r5,r6}\n\t"
            "stmia %[z_ptr],{r7,r8}\n\t" /* write out z[2].re, z[2].im */
            "sub %[z_ptr],%[z_ptr], #16\n\t" /* point z_ptr back to &z[0].re */
            "ldmia %[z_ptr],{r7,r8}\n\t" /* load r[0].re, r[0].im */
            
            "add r7,r7,r1\n\t"
            "sub r1,r7,r1,lsl #1\n\t"
            "add r8,r8,r2\n\t"
            "sub r2,r8,r2,lsl #1\n\t"
            
            "stmia %[z_ptr],{r7,r8}\n\t" /* write out z[0].re, z[0].im */
            "stmdb %[z4_ptr], {r1,r2}\n\t" /* write out z[4].re, z[4].im */
            : [z4_ptr] "+r" (m4), [z_ptr] "+r" (z), [temp] "=r" (temp)
            : 
            : "r1","r2","r3","r4","r5","r6","r7","r8","memory"
        );
    }
    
    z++;
    TRANSFORM_EQUAL(z,2);
}


#endif // CPU_ARM