/*
  * Copyright (c) 2012
  *      MIPS Technologies, Inc., California.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. Neither the name of the MIPS Technologies, Inc., nor the names of its
  *    contributors may be used to endorse or promote products derived from
  *    this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE MIPS TECHNOLOGIES, INC. ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE MIPS TECHNOLOGIES, INC. BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
  * Author:  Nedeljko Babic (nbabic@mips.com)
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #ifndef AVUTIL_FIXED_DSP_H
 #define AVUTIL_FIXED_DSP_H
 
 #include <stdint.h>
 #include "attributes.h"
 #include "common.h"
 #include "libavcodec/mathops.h"
 
 typedef struct AVFixedDSPContext {

     /* Assume len is a multiple of 16, and arrays are 32-byte aligned */
     /* Results of multiplications are scaled down by 31 bit (and rounded) if not
      * stated otherwise */
 

     /**
      * Overlap/add with window function.

      * Result is scaled down by "bits" bits.

      * Used primarily by MDCT-based audio codecs.
      * Source and destination vectors must overlap exactly or not at all.
      *
      * @param dst  result vector
      *             constraints: 16-byte aligned
      * @param src0 first source vector
      *             constraints: 16-byte aligned
      * @param src1 second source vector
      *             constraints: 16-byte aligned
      * @param win  half-window vector
      *             constraints: 16-byte aligned
      * @param len  length of vector
      *             constraints: multiple of 4
      * @param bits scaling parameter
      *
      */
     void (*vector_fmul_window_scaled)(int16_t *dst, const int32_t *src0, const int32_t *src1, const int32_t *win, int len, uint8_t bits);
 
     /**
      * Overlap/add with window function.
      * Used primarily by MDCT-based audio codecs.
      * Source and destination vectors must overlap exactly or not at all.
      *
      * @param dst  result vector
      *             constraints: 32-byte aligned
      * @param src0 first source vector
      *             constraints: 16-byte aligned
      * @param src1 second source vector
      *             constraints: 16-byte aligned
      * @param win  half-window vector
      *             constraints: 16-byte aligned
      * @param len  length of vector
      *             constraints: multiple of 4
      */
     void (*vector_fmul_window)(int32_t *dst, const int32_t *src0, const int32_t *src1, const int32_t *win, int len);
 

     /**
      * Fixed-point multiplication that calculates the entry wise product of two
      * vectors of integers and stores the result in a vector of integers.
      *
      * @param dst  output vector
      *             constraints: 32-byte aligned
      * @param src0 first input vector
      *             constraints: 32-byte aligned
      * @param src1 second input vector
      *             constraints: 32-byte aligned
      * @param len  number of elements in the input
      *             constraints: multiple of 16
      */
     void (*vector_fmul)(int *dst, const int *src0, const int *src1,
                         int len);
 
     void (*vector_fmul_reverse)(int *dst, const int *src0, const int *src1, int len);
     /**
      * Calculate the entry wise product of two vectors of integers, add a third vector of
      * integers and store the result in a vector of integers.
      *
      * @param dst  output vector
      *             constraints: 32-byte aligned
      * @param src0 first input vector
      *             constraints: 32-byte aligned
      * @param src1 second input vector
      *             constraints: 32-byte aligned
      * @param src2 third input vector
      *             constraints: 32-byte aligned
      * @param len  number of elements in the input
      *             constraints: multiple of 16
      */
     void (*vector_fmul_add)(int *dst, const int *src0, const int *src1,
                             const int *src2, int len);
 
     /**
      * Calculate the scalar product of two vectors of integers.
      *
      * @param v1  first vector, 16-byte aligned
      * @param v2  second vector, 16-byte aligned
      * @param len length of vectors, multiple of 4
      *
      * @return sum of elementwise products
      */
     int (*scalarproduct_fixed)(const int *v1, const int *v2, int len);
 
     /**
      * Calculate the sum and difference of two vectors of integers.
      *
      * @param v1  first input vector, sum output, 16-byte aligned
      * @param v2  second input vector, difference output, 16-byte aligned
      * @param len length of vectors, multiple of 4
      */
     void (*butterflies_fixed)(int *av_restrict v1, int *av_restrict v2, int len);

 } AVFixedDSPContext;
 
 /**
  * Allocate and initialize a fixed DSP context.
  * note: should be freed with a av_free call when no longer needed.
  *
  * @param strict  setting to non-zero avoids using functions which may not be IEEE-754 compliant
  */
 AVFixedDSPContext * avpriv_alloc_fixed_dsp(int strict);
 

 void ff_fixed_dsp_init_x86(AVFixedDSPContext *fdsp);
 

 /**
  * Calculate the square root
  *
  * @param x    input fixed point number
  *
  * @param bits format of fixed point number (32 - bits).bits
  *
  * note: input is normalized to (0, 1) fixed point value
  */
 
 static av_always_inline int fixed_sqrt(int x, int bits)
 {
     int retval, bit_mask, guess, square, i;
     int64_t accu;
     int shift1 = 30 - bits;
     int shift2 = bits - 15;
 
     if (shift1 > 0) retval = ff_sqrt(x << shift1);
     else retval = ff_sqrt(x >> -shift1);
 
     if (shift2 > 0) {
         retval = retval << shift2;
         bit_mask = (1 << (shift2 - 1));
 
         for (i=0; i<shift2; i++){
             guess = retval + bit_mask;
             accu = (int64_t)guess * guess;
             square = (int)((accu + bit_mask) >> bits);
             if (x >= square)
                 retval += bit_mask;
             bit_mask >>= 1;
         }
 
     }
     else retval >>= (-shift2);
 
     return retval;
 }
 
 #endif /* AVUTIL_FIXED_DSP_H */