/* ----------------------------------------------------------------------

   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator

   http://lammps.sandia.gov, Sandia National Laboratories

   Steve Plimpton, sjplimp@sandia.gov

   Copyright (2003) Sandia Corporation.  Under the terms of Contract

   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains

   certain rights in this software.  This software is distributed under 

   the GNU General Public License.

   See the README file in the top-level LAMMPS directory.

------------------------------------------------------------------------- */

/* ----------------------------------------------------------------------

   Contributing authors: Mike Brown (ORNL), brownw@ornl.gov

------------------------------------------------------------------------- */

#ifndef CRML_GPU_KERNEL

#define CRML_GPU_KERNEL

#define MAX_BIO_SHARED_TYPES 128

#ifdef _DOUBLE_DOUBLE

#define numtyp double

#define numtyp2 double2

#define numtyp4 double4

#define acctyp double

#define acctyp4 double4

#endif

#ifdef _SINGLE_DOUBLE

#define numtyp float

#define numtyp2 float2

#define numtyp4 float4

#define acctyp double

#define acctyp4 double4

#endif

#ifndef numtyp

#define numtyp float

#define numtyp2 float2

#define numtyp4 float4

#define acctyp float

#define acctyp4 float4

#endif

#define EWALD_F (numtyp)1.12837917

#define EWALD_P (numtyp)0.3275911

#define A1 (numtyp)0.254829592

#define A2 (numtyp)-0.284496736

#define A3 (numtyp)1.421413741

#define A4 (numtyp)-1.453152027

#define A5 (numtyp)1.061405429

#ifdef NV_KERNEL

#include "geryon/ucl_nv_kernel.h"

texture<float4> pos_tex;

texture<float> q_tex;

#ifdef _DOUBLE_DOUBLE

__inline double4 fetch_pos(const int& i, const double4 *pos)

{

  return pos[i];

}

__inline double fetch_q(const int& i, const double *q)

{

  return q[i];

}

#else

__inline float4 fetch_pos(const int& i, const float4 *pos)

{

  return tex1Dfetch(pos_tex, i);

}

__inline float fetch_q(const int& i, const float *q)

{

  return tex1Dfetch(q_tex, i);

}

#endif

#else

#pragma OPENCL EXTENSION cl_khr_fp64: enable

#define GLOBAL_ID_X get_global_id(0)

#define THREAD_ID_X get_local_id(0)

#define BLOCK_ID_X get_group_id(0)

#define BLOCK_SIZE_X get_local_size(0)

#define __syncthreads() barrier(CLK_LOCAL_MEM_FENCE)

#define __inline inline

#define fetch_pos(i,y) x_[i]

#define fetch_q(i,y) q_[i]

#endif

__kernel void kernel_pair(__global numtyp4 *x_, __global numtyp4 *lj1,

                          const int lj_types, 

                          __global numtyp *sp_lj_in, __global int *dev_nbor, 

                          __global acctyp4 *ans, __global acctyp *engv, 

                          const int eflag, const int vflag, const int inum, 

                          const int nall, const int nbor_pitch,

                          __global numtyp *q_, const numtyp cut_coulsq,

                          const numtyp qqrd2e, const numtyp g_ewald,

                          const numtyp denom_lj, const numtyp cut_bothsq, 

                          const numtyp cut_ljsq, const numtyp cut_lj_innersq) {

  // ii indexes the two interacting particles in gi

  int ii=GLOBAL_ID_X;

  __local numtyp sp_lj[8];

  sp_lj[0]=sp_lj_in[0];

  sp_lj[1]=sp_lj_in[1];

  sp_lj[2]=sp_lj_in[2];

  sp_lj[3]=sp_lj_in[3];

  sp_lj[4]=sp_lj_in[4];

  sp_lj[5]=sp_lj_in[5];

  sp_lj[6]=sp_lj_in[6];

  sp_lj[7]=sp_lj_in[7];

  if (ii<inum) {

    acctyp energy=(acctyp)0;

    acctyp e_coul=(acctyp)0;

    acctyp4 f;

    f.x=(acctyp)0;

    f.y=(acctyp)0;

    f.z=(acctyp)0;

    acctyp virial[6];

    for (int i=0; i<6; i++)

      virial[i]=(acctyp)0;

    __global int *nbor=dev_nbor+ii;

    int i=*nbor;

    nbor+=nbor_pitch;

    int numj=*nbor;

    nbor+=nbor_pitch;

    __global int *list_end=nbor+mul24(numj,nbor_pitch);

    numtyp4 ix=fetch_pos(i,x_); //x_[i];

    numtyp qtmp=fetch_q(i,q_);

    int itype=ix.w;

    for ( ; nbor<list_end; nbor+=nbor_pitch) {

      int j=*nbor;

      numtyp factor_lj, factor_coul;

      if (j < nall) {

        factor_lj = (numtyp)1.0;

        factor_coul = (numtyp)0.0;

      } else {

        factor_lj = sp_lj[j/nall];

        factor_coul = (numtyp)1.0-sp_lj[j/nall+4];

        j %= nall;

      }

      numtyp4 jx=fetch_pos(j,x_); //x_[j];

      int jtype=jx.w;

      // Compute r12

      numtyp delx = ix.x-jx.x;

      numtyp dely = ix.y-jx.y;

      numtyp delz = ix.z-jx.z;

      numtyp rsq = delx*delx+dely*dely+delz*delz;

      int mtype=itype*lj_types+jtype;

      if (rsq<cut_bothsq) {

        numtyp r2inv=(numtyp)1.0/rsq;

        numtyp forcecoul, force_lj, force, r6inv, prefactor, _erfc, switch1;

        if (rsq < cut_ljsq) {

          r6inv = r2inv*r2inv*r2inv;

          force_lj = factor_lj*r6inv*(lj1[mtype].x*r6inv-lj1[mtype].y);

          if (rsq > cut_lj_innersq) {

            switch1 = (cut_ljsq-rsq);

            numtyp switch2 = (numtyp)12.0*rsq*switch1*(rsq-cut_lj_innersq)/ 

                             denom_lj;

            switch1 *= switch1;

            switch1 *= (cut_ljsq+(numtyp)2.0*rsq-(numtyp)3.0*cut_lj_innersq)/

                       denom_lj;

            switch2 *= r6inv*(lj1[mtype].z*r6inv-lj1[mtype].w);

            force_lj = force_lj*switch1+switch2;

          }

        } else

          force_lj = (numtyp)0.0;

        if (rsq < cut_coulsq) {

          numtyp r = sqrt(rsq);

          numtyp grij = g_ewald * r;

          numtyp expm2 = exp(-grij*grij);

          numtyp t = (numtyp)1.0 / ((numtyp)1.0 + EWALD_P*grij);

          _erfc = t * (A1+t*(A2+t*(A3+t*(A4+t*A5)))) * expm2;

          prefactor = qqrd2e * qtmp*fetch_q(j,q_)/r;

          forcecoul = prefactor * (_erfc + EWALD_F*grij*expm2-factor_coul);

        } else {

          forcecoul = (numtyp)0.0;

          prefactor = (numtyp)0.0;

        }

        force = (force_lj + forcecoul) * r2inv;

        f.x+=delx*force;

        f.y+=dely*force;

        f.z+=delz*force;

        if (eflag>0) {

          e_coul += prefactor*(_erfc-factor_coul);

          if (rsq < cut_ljsq) {

            numtyp e=r6inv*(lj1[mtype].z*r6inv-lj1[mtype].w);

            if (rsq > cut_lj_innersq)

              e *= switch1;

            energy+=factor_lj*e;

          } 

        }

        if (vflag>0) {

          virial[0] += delx*delx*force;

          virial[1] += dely*dely*force;

          virial[2] += delz*delz*force;

          virial[3] += delx*dely*force;

          virial[4] += delx*delz*force;

          virial[5] += dely*delz*force;

        }

      }

    } // for nbor

    // Store answers

    __global acctyp *ap1=engv+ii;

    if (eflag>0) {

      *ap1=energy;

      ap1+=inum;

      *ap1=e_coul;

      ap1+=inum;

    }

    if (vflag>0) {

      for (int i=0; i<6; i++) {

        *ap1=virial[i];

        ap1+=inum;

      }

    }

    ans[ii]=f;

  } // if ii

}

__kernel void kernel_pair_fast(__global numtyp4 *x_, __global numtyp2 *ljd_in,

                               __global numtyp* sp_lj_in, __global int *dev_nbor, 

                               __global acctyp4 *ans, __global acctyp *engv, 

                               const int eflag, const int vflag, const int inum, 

                               const int nall, const int nbor_pitch,

                               __global numtyp *q_, const numtyp cut_coulsq, 

                               const numtyp qqrd2e, const numtyp g_ewald,

                               const numtyp denom_lj, const numtyp cut_bothsq, 

                               const numtyp cut_ljsq,

                               const numtyp cut_lj_innersq) {

  // ii indexes the two interacting particles in gi

  int ii=THREAD_ID_X;

  __local numtyp2 ljd[MAX_BIO_SHARED_TYPES];

  __local numtyp sp_lj[8];

  if (ii<8)

    sp_lj[ii]=sp_lj_in[ii];

  ljd[ii]=ljd_in[ii];

  ljd[ii+64]=ljd_in[ii+64];

  ii+=mul24((int)BLOCK_ID_X,(int)BLOCK_SIZE_X);

  __syncthreads();

  if (ii<inum) {

    acctyp energy=(acctyp)0;

    acctyp e_coul=(acctyp)0;

    acctyp4 f;

    f.x=(acctyp)0;

    f.y=(acctyp)0;

    f.z=(acctyp)0;

    acctyp virial[6];

    for (int i=0; i<6; i++)

      virial[i]=(acctyp)0;

    __global int *nbor=dev_nbor+ii;

    int i=*nbor;

    nbor+=nbor_pitch;

    int numj=*nbor;

    nbor+=nbor_pitch;

    __global int *list_end=nbor+mul24(numj,nbor_pitch);

    numtyp4 ix=fetch_pos(i,x_); //x_[i];

    numtyp qtmp=fetch_q(i,q_);

    int itype=ix.w;

    for ( ; nbor<list_end; nbor+=nbor_pitch) {

      int j=*nbor;

      numtyp factor_lj, factor_coul;

      if (j < nall) {

        factor_lj = (numtyp)1.0;

        factor_coul = (numtyp)0.0;

      } else {

        factor_lj = sp_lj[j/nall];

        factor_coul = (numtyp)1.0-sp_lj[j/nall+4];

        j %= nall;

      }

      numtyp4 jx=fetch_pos(j,x_); //x_[j];

      int jtype=jx.w;

      // Compute r12

      numtyp delx = ix.x-jx.x;

      numtyp dely = ix.y-jx.y;

      numtyp delz = ix.z-jx.z;

      numtyp rsq = delx*delx+dely*dely+delz*delz;

      if (rsq<cut_bothsq) {

        numtyp r2inv=(numtyp)1.0/rsq;

        numtyp forcecoul, force_lj, force, prefactor, _erfc, switch1;

        numtyp lj3, lj4;

        if (rsq < cut_ljsq) {

          numtyp eps = sqrt(ljd[itype].x*ljd[jtype].x);

          numtyp sig6 = (numtyp)0.5 * (ljd[itype].y+ljd[jtype].y);

          numtyp sig_r_6 = sig6*sig6*r2inv;

          sig_r_6 = sig_r_6*sig_r_6*sig_r_6;

          lj4 = (numtyp)4.0*eps*sig_r_6;

          lj3 = lj4*sig_r_6;

          force_lj = factor_lj*((numtyp)12.0 * lj3 - (numtyp)6.0 * lj4);

          if (rsq > cut_lj_innersq) {

            switch1 = (cut_ljsq-rsq);

            numtyp switch2 = (numtyp)12.0*rsq*switch1*(rsq-cut_lj_innersq)/ 

                             denom_lj;

            switch1 *= switch1;

            switch1 *= (cut_ljsq+(numtyp)2.0*rsq-(numtyp)3.0*cut_lj_innersq)/

                       denom_lj;

            switch2 *= lj3-lj4;

            force_lj = force_lj*switch1+switch2;

          }

        } else

          force_lj = (numtyp)0.0;

        if (rsq < cut_coulsq) {

          numtyp r = sqrt(rsq);

          numtyp grij = g_ewald * r;

          numtyp expm2 = exp(-grij*grij);

          numtyp t = (numtyp)1.0 / ((numtyp)1.0 + EWALD_P*grij);

          _erfc = t * (A1+t*(A2+t*(A3+t*(A4+t*A5)))) * expm2;

          prefactor = qqrd2e * qtmp*fetch_q(j,q_)/r;

          forcecoul = prefactor * (_erfc + EWALD_F*grij*expm2-factor_coul);

        } else {

          forcecoul = (numtyp)0.0;

          prefactor = (numtyp)0.0;

        }

        force = (force_lj + forcecoul) * r2inv;

        f.x+=delx*force;

        f.y+=dely*force;

        f.z+=delz*force;

        if (eflag>0) {

          e_coul += prefactor*(_erfc-factor_coul);

          if (rsq < cut_ljsq) {

            numtyp e=lj3-lj4;

            if (rsq > cut_lj_innersq)

              e *= switch1;

            energy+=factor_lj*e;

          }

        }

        if (vflag>0) {

          virial[0] += delx*delx*force;

          virial[1] += dely*dely*force;

          virial[2] += delz*delz*force;

          virial[3] += delx*dely*force;

          virial[4] += delx*delz*force;

          virial[5] += dely*delz*force;

        }

      }

    } // for nbor

    // Store answers

    __global acctyp *ap1=engv+ii;

    if (eflag>0) {

      *ap1=energy;

      ap1+=inum;

      *ap1=e_coul;

      ap1+=inum;

    }

    if (vflag>0) {

      for (int i=0; i<6; i++) {

        *ap1=virial[i];

        ap1+=inum;

      }

    }

    ans[ii]=f;

  } // if ii

}

#endif