/*
  Copyright (c) 2014, Evghenii Gaburov
  All rights reserved.

  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.

    * 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.

    * Neither the name of Intel Corporation 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 COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER
   OR CONTRIBUTORS 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.
*/

#include "typeT.h"

static inline
uniform int gcd(uniform int a, uniform int b)
{
  while ( a != 0 )
  {
    uniform int c = a;
    a = b%a;
    b = c;
  }
  return b;
}

  static inline
int __rj(const int i, const uniform int joverb, const uniform int m, const uniform int b)
{
  return (i + joverb) % m;
}

  static inline
int __di(const int i, const uniform int j, const uniform int m, const uniform int n, const uniform int joverb)
{
  return (((i+joverb) % m) + j*m) % n;
}

  static inline
int __sj(const int i, const uniform int j, const uniform int m, const uniform int n, const int iovera)
{
  return (j + i*n - iovera) % m;
}


#if 0
static inline
void transpose_serial(uniform T A[], const uniform int m, const uniform int n)
{
  const uniform int tmpSize = max(m,n) * programCount;
  uniform T   * uniform tmp    = uniform new uniform T  [tmpSize];
  uniform int * uniform joverb = uniform new uniform int[n];
  uniform int * uniform iovera = uniform new uniform int[m];

  uniform T (*uniform tmp2D)[programCount] = (uniform T (*uniform)[programCount])tmp;

  const uniform int c = gcd(m,n);
  const uniform int a = m/c;
  const uniform int b = n/c;
  foreach (j = 0 ... n)
    joverb[j] = j/b;
  foreach (i = 0 ... m)
    iovera[i] = i/a;

  if (c > 1)
  {
    for (uniform int j = 0; j < n; j++)
    {
      const uniform int base = j*m;
      const uniform int __joverb = joverb[j];
      foreach (i = 0 ... m)
        tmp[i] = A[base + __rj(i,__joverb,m,b)];
      foreach (i = 0 ... m)
        A[base + i] = tmp[i];
    }
  }

  foreach (i = 0 ... m)
  {
    for (uniform int j = 0; j < n; j++)
      tmp2D[__di(i,j,m,n,joverb[j])][programIndex] = A[j*m + i];
    for (uniform int j = 0; j < n; j++)
      A[j*m + i] = tmp2D[j][programIndex];
  }

  for (uniform int j = 0; j < n; j++)
  {
    const uniform int base = j*m;
    foreach (i = 0 ... m)
      tmp[i] = A[base + __sj(i,j,m,n,iovera[i])];
    foreach (i = 0 ... m)
      A[base + i] = tmp[i];
  }

  delete iovera;
  delete joverb;
  delete tmp;
}
#endif

static uniform int * uniform joverb = NULL;
static uniform int * uniform iovera = NULL;
static uniform int a,b,c;

static
void transpose_init(const uniform int m, const uniform int n, const uniform int nTask)
{
  joverb = uniform new uniform int[n];
  iovera = uniform new uniform int[m];

  c = gcd(m,n);
  a = m/c;
  b = n/c;
  foreach (j = 0 ... n)
    joverb[j] = j/b;
  foreach (i = 0 ... m)
    iovera[i] = i/a;
}

static
void transpose_finalize()
{
  delete iovera;
  delete joverb;
}

task
void transpose_step1(uniform T A[], const uniform int m, const uniform int n)
{
  const uniform int n_per_task = (n + taskCount - 1)/taskCount;
  const uniform int nibeg = taskIndex * n_per_task;
  const uniform int niend = min(nibeg + n_per_task, n);

  uniform T * uniform tmp = uniform new uniform T[m];

  for (uniform int j = nibeg; j < niend; j++)
  {
    const uniform int base = j*m;
    const uniform int __joverb = joverb[j];
    foreach (i = 0 ... m)
      tmp[i] = A[base + __rj(i,__joverb,m,b)];
    foreach (i = 0 ... m)
      A[base + i] = tmp[i];
  }

  delete tmp;
}

task
void transpose_step2(uniform T A[], const uniform int m, const uniform int n)
{
  const uniform int m_per_task = (m + taskCount - 1)/taskCount;
  const uniform int mibeg = taskIndex * m_per_task;
  const uniform int miend = min(mibeg + m_per_task, m);

  uniform  T * uniform tmp = uniform new uniform T[n*programCount];

  uniform T (*uniform tmp2D)[programCount] = (uniform T (*uniform)[programCount])tmp;
  foreach (i = mibeg ... miend)
  {
    for (uniform int j = 0; j < n; j++)
      tmp2D[__di(i,j,m,n,joverb[j])][programIndex] = A[j*m + i];
    for (uniform int j = 0; j < n; j++)
      A[j*m + i] = tmp2D[j][programIndex];
  }

  delete tmp;
}

task
void transpose_step3(uniform T A[], const uniform int m, const uniform int n)
{
  const uniform int n_per_task = (n + taskCount - 1)/taskCount;
  const uniform int nibeg = taskIndex * n_per_task;
  const uniform int niend = min(nibeg + n_per_task, n);

  uniform  T * uniform tmp = uniform new uniform T[m];

  for (uniform int j = nibeg; j < niend; j++)
  {
    const uniform int base = j*m;
    foreach (i = 0 ... m)
      tmp[i] = A[base + __sj(i,j,m,n,iovera[i])];
    foreach (i = 0 ... m)
      A[base + i] = tmp[i];
  }

  delete tmp;
}

export
void transpose(uniform T A[], const uniform int m, const uniform int n)
{
#if 0
  transpose_serial(A, m, n);
#else
  const uniform int nTask = 32*8; //num_cores()*4;
  transpose_init(m,n,nTask);

  launch [nTask] transpose_step1(A, m, n);
  sync;

  launch [nTask] transpose_step2(A, m, n);
  sync;

  launch [nTask] transpose_step3(A, m, n);
  sync;

  transpose_finalize();
#endif
  sync;
}