/*
  * jfdctfst.c
  *
  * This file is part of the Independent JPEG Group's software.

  *
  * The authors make NO WARRANTY or representation, either express or implied,
  * with respect to this software, its quality, accuracy, merchantability, or
  * fitness for a particular purpose.  This software is provided "AS IS", and
  * you, its user, assume the entire risk as to its quality and accuracy.
  *
  * This software is copyright (C) 1994-1996, Thomas G. Lane.
  * All Rights Reserved except as specified below.
  *
  * Permission is hereby granted to use, copy, modify, and distribute this
  * software (or portions thereof) for any purpose, without fee, subject to
  * these conditions:
  * (1) If any part of the source code for this software is distributed, then
  * this README file must be included, with this copyright and no-warranty
  * notice unaltered; and any additions, deletions, or changes to the original
  * files must be clearly indicated in accompanying documentation.
  * (2) If only executable code is distributed, then the accompanying
  * documentation must state that "this software is based in part on the work
  * of the Independent JPEG Group".
  * (3) Permission for use of this software is granted only if the user accepts
  * full responsibility for any undesirable consequences; the authors accept
  * NO LIABILITY for damages of any kind.
  *
  * These conditions apply to any software derived from or based on the IJG
  * code, not just to the unmodified library.  If you use our work, you ought
  * to acknowledge us.
  *
  * Permission is NOT granted for the use of any IJG author's name or company
  * name in advertising or publicity relating to this software or products
  * derived from it.  This software may be referred to only as "the Independent
  * JPEG Group's software".
  *
  * We specifically permit and encourage the use of this software as the basis
  * of commercial products, provided that all warranty or liability claims are
  * assumed by the product vendor.

  *
  * This file contains a fast, not so accurate integer implementation of the
  * forward DCT (Discrete Cosine Transform).
  *
  * A 2-D DCT can be done by 1-D DCT on each row followed by 1-D DCT
  * on each column.  Direct algorithms are also available, but they are
  * much more complex and seem not to be any faster when reduced to code.
  *
  * This implementation is based on Arai, Agui, and Nakajima's algorithm for
  * scaled DCT.  Their original paper (Trans. IEICE E-71(11):1095) is in
  * Japanese, but the algorithm is described in the Pennebaker & Mitchell
  * JPEG textbook (see REFERENCES section in file README).  The following code
  * is based directly on figure 4-8 in P&M.
  * While an 8-point DCT cannot be done in less than 11 multiplies, it is
  * possible to arrange the computation so that many of the multiplies are
  * simple scalings of the final outputs.  These multiplies can then be
  * folded into the multiplications or divisions by the JPEG quantization
  * table entries.  The AA&N method leaves only 5 multiplies and 29 adds
  * to be done in the DCT itself.
  * The primary disadvantage of this method is that with fixed-point math,
  * accuracy is lost due to imprecise representation of the scaled
  * quantization values.  The smaller the quantization table entry, the less
  * precise the scaled value, so this implementation does worse with high-
  * quality-setting files than with low-quality ones.
  */
 

 /**

  * @file

  * Independent JPEG Group's fast AAN dct.
  */

 #include <stdlib.h>
 #include <stdio.h>

 #include "libavutil/common.h"

 #include "dsputil.h"
 
 #define DCTSIZE 8
 #define GLOBAL(x) x
 #define RIGHT_SHIFT(x, n) ((x) >> (n))
 
 /*
  * This module is specialized to the case DCTSIZE = 8.
  */
 
 #if DCTSIZE != 8
   Sorry, this code only copes with 8x8 DCTs. /* deliberate syntax err */
 #endif
 
 
 /* Scaling decisions are generally the same as in the LL&M algorithm;
  * see jfdctint.c for more details.  However, we choose to descale
  * (right shift) multiplication products as soon as they are formed,
  * rather than carrying additional fractional bits into subsequent additions.
  * This compromises accuracy slightly, but it lets us save a few shifts.
  * More importantly, 16-bit arithmetic is then adequate (for 8-bit samples)
  * everywhere except in the multiplications proper; this saves a good deal
  * of work on 16-bit-int machines.
  *
  * Again to save a few shifts, the intermediate results between pass 1 and
  * pass 2 are not upscaled, but are represented only to integral precision.
  *
  * A final compromise is to represent the multiplicative constants to only
  * 8 fractional bits, rather than 13.  This saves some shifting work on some
  * machines, and may also reduce the cost of multiplication (since there
  * are fewer one-bits in the constants).
  */
 
 #define CONST_BITS  8
 
 
 /* Some C compilers fail to reduce "FIX(constant)" at compile time, thus
  * causing a lot of useless floating-point operations at run time.
  * To get around this we use the following pre-calculated constants.
  * If you change CONST_BITS you may want to add appropriate values.
  * (With a reasonable C compiler, you can just rely on the FIX() macro...)
  */
 
 #if CONST_BITS == 8

 #define FIX_0_382683433  ((int32_t)   98)       /* FIX(0.382683433) */
 #define FIX_0_541196100  ((int32_t)  139)       /* FIX(0.541196100) */
 #define FIX_0_707106781  ((int32_t)  181)       /* FIX(0.707106781) */
 #define FIX_1_306562965  ((int32_t)  334)       /* FIX(1.306562965) */

 #else
 #define FIX_0_382683433  FIX(0.382683433)
 #define FIX_0_541196100  FIX(0.541196100)
 #define FIX_0_707106781  FIX(0.707106781)
 #define FIX_1_306562965  FIX(1.306562965)
 #endif
 
 
 /* We can gain a little more speed, with a further compromise in accuracy,
  * by omitting the addition in a descaling shift.  This yields an incorrectly
  * rounded result half the time...
  */
 
 #ifndef USE_ACCURATE_ROUNDING
 #undef DESCALE
 #define DESCALE(x,n)  RIGHT_SHIFT(x, n)
 #endif
 
 

 /* Multiply a DCTELEM variable by an int32_t constant, and immediately

  * descale to yield a DCTELEM result.
  */
 
 #define MULTIPLY(var,const)  ((DCTELEM) DESCALE((var) * (const), CONST_BITS))
 

 static av_always_inline void row_fdct(DCTELEM * data){

   int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
   int tmp10, tmp11, tmp12, tmp13;
   int z1, z2, z3, z4, z5, z11, z13;

   DCTELEM *dataptr;
   int ctr;
 
   /* Pass 1: process rows. */
 
   dataptr = data;
   for (ctr = DCTSIZE-1; ctr >= 0; ctr--) {
     tmp0 = dataptr[0] + dataptr[7];
     tmp7 = dataptr[0] - dataptr[7];
     tmp1 = dataptr[1] + dataptr[6];
     tmp6 = dataptr[1] - dataptr[6];
     tmp2 = dataptr[2] + dataptr[5];
     tmp5 = dataptr[2] - dataptr[5];
     tmp3 = dataptr[3] + dataptr[4];
     tmp4 = dataptr[3] - dataptr[4];

     /* Even part */

     tmp10 = tmp0 + tmp3;        /* phase 2 */

     tmp13 = tmp0 - tmp3;
     tmp11 = tmp1 + tmp2;
     tmp12 = tmp1 - tmp2;

     dataptr[0] = tmp10 + tmp11; /* phase 3 */
     dataptr[4] = tmp10 - tmp11;

     z1 = MULTIPLY(tmp12 + tmp13, FIX_0_707106781); /* c4 */

     dataptr[2] = tmp13 + z1;    /* phase 5 */

     dataptr[6] = tmp13 - z1;

     /* Odd part */
 

     tmp10 = tmp4 + tmp5;        /* phase 2 */

     tmp11 = tmp5 + tmp6;
     tmp12 = tmp6 + tmp7;
 
     /* The rotator is modified from fig 4-8 to avoid extra negations. */
     z5 = MULTIPLY(tmp10 - tmp12, FIX_0_382683433); /* c6 */

     z2 = MULTIPLY(tmp10, FIX_0_541196100) + z5;    /* c2-c6 */
     z4 = MULTIPLY(tmp12, FIX_1_306562965) + z5;    /* c2+c6 */
     z3 = MULTIPLY(tmp11, FIX_0_707106781);         /* c4 */

     z11 = tmp7 + z3;            /* phase 5 */

     z13 = tmp7 - z3;
 

     dataptr[5] = z13 + z2;      /* phase 6 */

     dataptr[3] = z13 - z2;
     dataptr[1] = z11 + z4;
     dataptr[7] = z11 - z4;
 

     dataptr += DCTSIZE;         /* advance pointer to next row */

   }

 }

 /*
  * Perform the forward DCT on one block of samples.
  */
 
 GLOBAL(void)
 fdct_ifast (DCTELEM * data)
 {

   int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
   int tmp10, tmp11, tmp12, tmp13;
   int z1, z2, z3, z4, z5, z11, z13;

   DCTELEM *dataptr;
   int ctr;
 
   row_fdct(data);

   /* Pass 2: process columns. */
 
   dataptr = data;
   for (ctr = DCTSIZE-1; ctr >= 0; ctr--) {
     tmp0 = dataptr[DCTSIZE*0] + dataptr[DCTSIZE*7];
     tmp7 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*7];
     tmp1 = dataptr[DCTSIZE*1] + dataptr[DCTSIZE*6];
     tmp6 = dataptr[DCTSIZE*1] - dataptr[DCTSIZE*6];
     tmp2 = dataptr[DCTSIZE*2] + dataptr[DCTSIZE*5];
     tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*5];
     tmp3 = dataptr[DCTSIZE*3] + dataptr[DCTSIZE*4];
     tmp4 = dataptr[DCTSIZE*3] - dataptr[DCTSIZE*4];

     /* Even part */

     tmp10 = tmp0 + tmp3;        /* phase 2 */

     tmp13 = tmp0 - tmp3;
     tmp11 = tmp1 + tmp2;
     tmp12 = tmp1 - tmp2;

     dataptr[DCTSIZE*0] = tmp10 + tmp11; /* phase 3 */
     dataptr[DCTSIZE*4] = tmp10 - tmp11;

     z1 = MULTIPLY(tmp12 + tmp13, FIX_0_707106781); /* c4 */
     dataptr[DCTSIZE*2] = tmp13 + z1; /* phase 5 */
     dataptr[DCTSIZE*6] = tmp13 - z1;

     /* Odd part */
 

     tmp10 = tmp4 + tmp5;        /* phase 2 */

     tmp11 = tmp5 + tmp6;
     tmp12 = tmp6 + tmp7;
 
     /* The rotator is modified from fig 4-8 to avoid extra negations. */
     z5 = MULTIPLY(tmp10 - tmp12, FIX_0_382683433); /* c6 */
     z2 = MULTIPLY(tmp10, FIX_0_541196100) + z5; /* c2-c6 */
     z4 = MULTIPLY(tmp12, FIX_1_306562965) + z5; /* c2+c6 */
     z3 = MULTIPLY(tmp11, FIX_0_707106781); /* c4 */
 

     z11 = tmp7 + z3;            /* phase 5 */

     z13 = tmp7 - z3;
 
     dataptr[DCTSIZE*5] = z13 + z2; /* phase 6 */
     dataptr[DCTSIZE*3] = z13 - z2;
     dataptr[DCTSIZE*1] = z11 + z4;
     dataptr[DCTSIZE*7] = z11 - z4;
 

     dataptr++;                  /* advance pointer to next column */

   }
 }

 /*
  * Perform the forward 2-4-8 DCT on one block of samples.
  */
 
 GLOBAL(void)
 fdct_ifast248 (DCTELEM * data)
 {

   int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
   int tmp10, tmp11, tmp12, tmp13;
   int z1;

   DCTELEM *dataptr;
   int ctr;
 

   row_fdct(data);

   /* Pass 2: process columns. */
 
   dataptr = data;
   for (ctr = DCTSIZE-1; ctr >= 0; ctr--) {
     tmp0 = dataptr[DCTSIZE*0] + dataptr[DCTSIZE*1];
     tmp1 = dataptr[DCTSIZE*2] + dataptr[DCTSIZE*3];
     tmp2 = dataptr[DCTSIZE*4] + dataptr[DCTSIZE*5];
     tmp3 = dataptr[DCTSIZE*6] + dataptr[DCTSIZE*7];
     tmp4 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*1];
     tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*3];
     tmp6 = dataptr[DCTSIZE*4] - dataptr[DCTSIZE*5];
     tmp7 = dataptr[DCTSIZE*6] - dataptr[DCTSIZE*7];
 
     /* Even part */

     tmp10 = tmp0 + tmp3;
     tmp11 = tmp1 + tmp2;
     tmp12 = tmp1 - tmp2;
     tmp13 = tmp0 - tmp3;

     dataptr[DCTSIZE*0] = tmp10 + tmp11;
     dataptr[DCTSIZE*4] = tmp10 - tmp11;

     z1 = MULTIPLY(tmp12 + tmp13, FIX_0_707106781);
     dataptr[DCTSIZE*2] = tmp13 + z1;
     dataptr[DCTSIZE*6] = tmp13 - z1;
 
     tmp10 = tmp4 + tmp7;
     tmp11 = tmp5 + tmp6;
     tmp12 = tmp5 - tmp6;
     tmp13 = tmp4 - tmp7;

     dataptr[DCTSIZE*1] = tmp10 + tmp11;
     dataptr[DCTSIZE*5] = tmp10 - tmp11;

     z1 = MULTIPLY(tmp12 + tmp13, FIX_0_707106781);
     dataptr[DCTSIZE*3] = tmp13 + z1;
     dataptr[DCTSIZE*7] = tmp13 - z1;

     dataptr++;                        /* advance pointer to next column */

   }
 }
 

 
 #undef GLOBAL
 #undef CONST_BITS
 #undef DESCALE
 #undef FIX_0_541196100
 #undef FIX_1_306562965