// **************************************************************************
//                                   eam.cu
//                             -------------------
//                   Trung Dac Nguyen, W. Michael Brown (ORNL)
//
//  Device code for acceleration of the eam pair style
//
// __________________________________________________________________________
//    This file is part of the LAMMPS Accelerator Library (LAMMPS_AL)
// __________________________________________________________________________
//
//    begin                :
//    email                : brownw@ornl.gov nguyentd@ornl.gov
// ***************************************************************************

#if defined(NV_KERNEL) || defined(USE_HIP)
#include "lal_aux_fun1.h"

#ifndef _DOUBLE_DOUBLE
_texture( pos_tex,float4);
_texture( fp_tex,float);
_texture( rhor_sp1_tex,float4);
_texture( rhor_sp2_tex,float4);
_texture( frho_sp1_tex,float4);
_texture( frho_sp2_tex,float4);
_texture( z2r_sp1_tex,float4);
_texture( z2r_sp2_tex,float4);
#else
_texture( pos_tex,int4);
_texture( fp_tex,int2);
_texture( rhor_sp1_tex,int4);
_texture( rhor_sp2_tex,int4);
_texture( frho_sp1_tex,int4);
_texture( frho_sp2_tex,int4);
_texture( z2r_sp1_tex,int4);
_texture( z2r_sp2_tex,int4);
#endif

#if (__CUDACC_VER_MAJOR__ >= 11)
#define fp_tex fp_
#define rhor_sp1_tex rhor_spline1
#define rhor_sp2_tex rhor_spline2
#define frho_sp1_tex frho_spline1
#define frho_sp2_tex frho_spline2
#define z2r_sp1_tex z2r_spline1
#define z2r_sp2_tex z2r_spline2
#endif

#else

#define pos_tex x_
#define fp_tex fp_
#define rhor_sp1_tex rhor_spline1
#define rhor_sp2_tex rhor_spline2
#define frho_sp1_tex frho_spline1
#define frho_sp2_tex frho_spline2
#define z2r_sp1_tex z2r_spline1
#define z2r_sp2_tex z2r_spline2

#endif

#define MIN(A,B) ((A) < (B) ? (A) : (B))
#define MAX(A,B) ((A) > (B) ? (A) : (B))

#if (SHUFFLE_AVAIL == 0)

#define local_allocate_store_energy_fp()                                    \
    __local acctyp red_acc[BLOCK_PAIR];

#define store_energy_fp(rho,energy,ii,inum,tid,t_per_atom,offset,           \
                        eflag,vflag,engv,rdrho,nrho,i,rhomax,tfrho)         \
  if (t_per_atom>1) {                                                       \
    red_acc[tid]=rho;                                                       \
    for (unsigned int s=t_per_atom/2; s>0; s>>=1) {                         \
      simdsync();                                                           \
      if (offset < s)                                                       \
         red_acc[tid] += red_acc[tid+s];                                    \
      }                                                                     \
      rho=red_acc[tid];                                                     \
  }                                                                         \
  if (offset==0 && ii<inum) {                                               \
    numtyp p = rho*rdrho + (numtyp)1.0;                                     \
    int m=p;                                                                \
    m = MAX(1,MIN(m,nrho-1));                                               \
    p -= m;                                                                 \
    p = MIN(p,(numtyp)1.0);                                                 \
    int index = tfrho*(nrho+1)+m;                                           \
    numtyp4 coeff; fetch4(coeff,index,frho_sp1_tex);                        \
    numtyp fp = (coeff.x*p + coeff.y)*p + coeff.z;                          \
    fp_[i]=fp;                                                              \
    if (EVFLAG && eflag) {                                                  \
      fetch4(coeff,index,frho_sp2_tex);                                     \
      energy = ((coeff.x*p + coeff.y)*p + coeff.z)*p + coeff.w;             \
      if (rho > rhomax) energy += fp*(rho-rhomax);                          \
      engv[ii]=energy;                                                      \
    }                                                                       \
  }

#define local_allocate_store_answers_eam()                                  \
    __local acctyp red_acc[6][BLOCK_PAIR];

#define store_answers_eam(f, energy, virial, ii, inum, tid, t_per_atom,     \
                      offset, elag, vflag, ans, engv)                       \
  if (t_per_atom>1) {                                                       \
    red_acc[0][tid]=f.x;                                                    \
    red_acc[1][tid]=f.y;                                                    \
    red_acc[2][tid]=f.z;                                                    \
    red_acc[3][tid]=energy;                                                 \
    for (unsigned int s=t_per_atom/2; s>0; s>>=1) {                         \
      simdsync();                                                           \
      if (offset < s) {                                                     \
        for (int r=0; r<4; r++)                                             \
          red_acc[r][tid] += red_acc[r][tid+s];                             \
      }                                                                     \
    }                                                                       \
    f.x=red_acc[0][tid];                                                    \
    f.y=red_acc[1][tid];                                                    \
    f.z=red_acc[2][tid];                                                    \
    energy=red_acc[3][tid];                                                 \
    if (EVFLAG && vflag) {                                                  \
      simdsync();                                                           \
      for (int r=0; r<6; r++)                                               \
        red_acc[r][tid]=virial[r];                                          \
      for (unsigned int s=t_per_atom/2; s>0; s>>=1) {                       \
        simdsync();                                                         \
        if (offset < s) {                                                   \
          for (int r=0; r<6; r++)                                           \
            red_acc[r][tid] += red_acc[r][tid+s];                           \
        }                                                                   \
      }                                                                     \
      for (int r=0; r<6; r++)                                               \
        virial[r]=red_acc[r][tid];                                          \
    }                                                                       \
  }                                                                         \
  if (offset==0 && ii<inum) {                                               \
    int ei=ii;                                                              \
    if (EVFLAG && eflag) {                                                  \
      engv[ei]+=energy*(acctyp)0.5;                                         \
      ei+=inum;                                                             \
    }                                                                       \
    if (EVFLAG && vflag) {                                                  \
      for (int i=0; i<6; i++) {                                             \
        engv[ei]=virial[i]*(acctyp)0.5;                                     \
        ei+=inum;                                                           \
      }                                                                     \
    }                                                                       \
    ans[ii]=f;                                                              \
  }

#else

#define local_allocate_store_energy_fp()

#define store_energy_fp(rho,energy,ii,inum,tid,t_per_atom,offset,           \
                        eflag,vflag,engv,rdrho,nrho,i,rhomax,tfrho)         \
  if (t_per_atom>1) {                                                       \
    for (unsigned int s=t_per_atom/2; s>0; s>>=1)                           \
      rho += shfl_down(rho, s, t_per_atom);                                 \
  }                                                                         \
  if (offset==0 && ii<inum) {                                               \
    numtyp p = rho*rdrho + (numtyp)1.0;                                     \
    int m=p;                                                                \
    m = MAX(1,MIN(m,nrho-1));                                               \
    p -= m;                                                                 \
    p = MIN(p,(numtyp)1.0);                                                 \
    int index = tfrho*(nrho+1)+m;                                           \
    numtyp4 coeff; fetch4(coeff,index,frho_sp1_tex);                        \
    numtyp fp = (coeff.x*p + coeff.y)*p + coeff.z;                          \
    fp_[i]=fp;                                                              \
    if (EVFLAG && eflag) {                                                  \
      fetch4(coeff,index,frho_sp2_tex);                                     \
      energy = ((coeff.x*p + coeff.y)*p + coeff.z)*p + coeff.w;             \
      if (rho > rhomax) energy += fp*(rho-rhomax);                          \
      engv[ii]=energy;                                                      \
    }                                                                       \
  }

#define local_allocate_store_answers_eam()

#define store_answers_eam(f, energy, virial, ii, inum, tid, t_per_atom,     \
                          offset, eflag, vflag, ans, engv)                  \
  if (t_per_atom>1) {                                                       \
    for (unsigned int s=t_per_atom/2; s>0; s>>=1) {                         \
      f.x += shfl_down(f.x, s, t_per_atom);                                 \
      f.y += shfl_down(f.y, s, t_per_atom);                                 \
      f.z += shfl_down(f.z, s, t_per_atom);                                 \
      if (EVFLAG) energy += shfl_down(energy, s, t_per_atom);               \
    }                                                                       \
    if (EVFLAG && vflag) {                                                  \
      for (unsigned int s=t_per_atom/2; s>0; s>>=1) {                       \
        for (int r=0; r<6; r++)                                             \
          virial[r] += shfl_down(virial[r], s, t_per_atom);                 \
      }                                                                     \
    }                                                                       \
  }                                                                         \
  if (offset==0 && ii<inum) {                                               \
    int ei=ii;                                                              \
    if (EVFLAG && eflag) {                                                  \
      engv[ei]+=energy*(acctyp)0.5;                                         \
      ei+=inum;                                                             \
    }                                                                       \
    if (EVFLAG && vflag) {                                                  \
      for (int i=0; i<6; i++) {                                             \
        engv[ei]=virial[i]*(acctyp)0.5;                                     \
        ei+=inum;                                                           \
      }                                                                     \
    }                                                                       \
    ans[ii]=f;                                                              \
  }

#endif

__kernel void k_energy(const __global numtyp4 *restrict x_,
                       const __global int2 *restrict type2rhor_z2r,
                       const __global int *restrict type2frho,
                       const __global numtyp4 *restrict rhor_spline2,
                       const __global numtyp4 *restrict frho_spline1,
                       const __global numtyp4 *restrict frho_spline2,
                       const __global int *dev_nbor,
                       const __global int *dev_packed,
                       __global numtyp *restrict fp_,
                       __global acctyp *restrict engv,
                       const int eflag, const int inum, const int nbor_pitch,
                       const int ntypes,  const numtyp cutforcesq,
                       const numtyp rdr, const numtyp rdrho,
                       const numtyp rhomax, const int nrho,
                       const int nr, const int t_per_atom) {
  int tid, ii, offset, i, itype;
  atom_info(t_per_atom,ii,tid,offset);

  int n_stride;
  local_allocate_store_energy_fp();

  acctyp rho = (acctyp)0;
  acctyp energy;
  if (EVFLAG && eflag) energy=(acctyp)0;

  if (ii<inum) {
    int nbor, nbor_end, numj;
    nbor_info(dev_nbor,dev_packed,nbor_pitch,t_per_atom,ii,offset,i,numj,
              n_stride,nbor_end,nbor);

    numtyp4 ix; fetch4(ix,i,pos_tex); //x_[i];
    itype=ix.w;

    for ( ; nbor<nbor_end; nbor+=n_stride) {
      int j=dev_packed[nbor];
      j &= NEIGHMASK;

      numtyp4 jx; fetch4(jx,j,pos_tex); //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<cutforcesq) {
        numtyp p = ucl_sqrt(rsq)*rdr + (numtyp)1.0;
        int m=p;
        m = MIN(m,nr-1);
        p -= m;
        p = MIN(p,(numtyp)1.0);

        int mtype = jtype*ntypes+itype;
        int index = type2rhor_z2r[mtype].x*(nr+1)+m;
        numtyp4 coeff; fetch4(coeff,index,rhor_sp2_tex);
        rho += ((coeff.x*p + coeff.y)*p + coeff.z)*p + coeff.w;
      }
    } // for nbor
  } // if ii
  const numtyp tfrho=type2frho[itype];
  store_energy_fp(rho,energy,ii,inum,tid,t_per_atom,offset,
                  eflag,vflag,engv,rdrho,nrho,i,rhomax,tfrho);
}

__kernel void k_energy_fast(const __global numtyp4 *restrict x_,
                            const __global int2 *restrict type2rhor_z2r_in,
                            const __global int *restrict type2frho_in,
                            const __global numtyp4 *restrict rhor_spline2,
                            const __global numtyp4 *restrict frho_spline1,
                            const __global numtyp4 *restrict frho_spline2,
                            const __global int *dev_nbor,
                            const __global int *dev_packed,
                            __global numtyp *restrict fp_,
                            __global acctyp *restrict engv,
                            const int eflag,  const int inum,
                            const int nbor_pitch, const int ntypes,
                            const numtyp cutforcesq,  const numtyp rdr,
                            const numtyp rdrho, const numtyp rhomax,
                            const int nrho, const int nr,
                            const int t_per_atom) {
  int tid, ii, offset, i, itype;
  atom_info(t_per_atom,ii,tid,offset);

  #ifndef ONETYPE
  __local int2 type2rhor_z2r[MAX_SHARED_TYPES*MAX_SHARED_TYPES];
  __local int type2frho[MAX_SHARED_TYPES];
  if (tid<MAX_SHARED_TYPES*MAX_SHARED_TYPES) {
    type2rhor_z2r[tid]=type2rhor_z2r_in[tid];
  }
  if (tid<MAX_SHARED_TYPES) {
    type2frho[tid]=type2frho_in[tid];
  }
  __syncthreads();
  #else
  const numtyp type2rhor_z2rx=
    type2rhor_z2r_in[ONETYPE*MAX_SHARED_TYPES+ONETYPE].x;
  const numtyp tfrho=type2frho_in[ONETYPE];
  #endif

  int n_stride;
  local_allocate_store_energy_fp();

  acctyp rho = (acctyp)0;
  acctyp energy;
  if (EVFLAG && eflag) energy=(acctyp)0;

  if (ii<inum) {
    int nbor, nbor_end, numj;
    nbor_info(dev_nbor,dev_packed,nbor_pitch,t_per_atom,ii,offset,i,numj,
              n_stride,nbor_end,nbor);

    numtyp4 ix; fetch4(ix,i,pos_tex); //x_[i];
    #ifndef ONETYPE
    itype=ix.w;
    #endif

    for ( ; nbor<nbor_end; nbor+=n_stride) {
      int j=dev_packed[nbor];
      j &= NEIGHMASK;

      numtyp4 jx; fetch4(jx,j,pos_tex); //x_[j];

      // 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<cutforcesq) {
        numtyp p = ucl_sqrt(rsq)*rdr + (numtyp)1.0;
        int m=p;
        m = MIN(m,nr-1);
        p -= m;
        p = MIN(p,(numtyp)1.0);

        #ifndef ONETYPE
        int jtype=fast_mul((int)MAX_SHARED_TYPES,jx.w);
        int mtype = jtype+itype;
        int index = type2rhor_z2r[mtype].x*(nr+1)+m;
        #else
        int index = type2rhor_z2rx*(nr+1)+m;
        #endif
        numtyp4 coeff; fetch4(coeff,index,rhor_sp2_tex);
        rho += ((coeff.x*p + coeff.y)*p + coeff.z)*p + coeff.w;
      }
    } // for nbor
  } // if ii
  #ifndef ONETYPE
  const numtyp tfrho=type2frho[itype];
  #endif
  store_energy_fp(rho,energy,ii,inum,tid,t_per_atom,offset,
                  eflag,vflag,engv,rdrho,nrho,i,rhomax,tfrho);
}

__kernel void k_eam(const __global numtyp4 *restrict x_,
                    const __global numtyp *fp_,
                    const __global int2 *type2rhor_z2r,
                    const __global numtyp4 *rhor_spline1,
                    const __global numtyp4 *z2r_spline1,
                    const __global numtyp4 *z2r_spline2,
                    const __global int *dev_nbor,
                    const __global int *dev_packed,
                    __global acctyp4 *ans,
                    __global acctyp *engv,
                    const int eflag, const int vflag,  const int inum,
                    const int nbor_pitch, const int ntypes,
                    const numtyp cutforcesq,  const numtyp rdr, const int nr,
                    const int t_per_atom) {
  int tid, ii, offset;
  atom_info(t_per_atom,ii,tid,offset);

  int n_stride;
  local_allocate_store_answers_eam();

  acctyp4 f;
  f.x=(acctyp)0; f.y=(acctyp)0; f.z=(acctyp)0;
  acctyp energy, virial[6];
  if (EVFLAG) {
    energy=(acctyp)0;
    for (int i=0; i<6; i++) virial[i]=(acctyp)0;
  }

  if (ii<inum) {
    int nbor, nbor_end;
    int i, numj;
    nbor_info(dev_nbor,dev_packed,nbor_pitch,t_per_atom,ii,offset,i,numj,
              n_stride,nbor_end,nbor);

    numtyp4 ix; fetch4(ix,i,pos_tex); //x_[i];
    numtyp ifp; fetch(ifp,i,fp_tex);  //fp_[i];
    int itype=ix.w;

    for ( ; nbor<nbor_end; nbor+=n_stride) {
      int j=dev_packed[nbor];
      j &= NEIGHMASK;

      numtyp4 jx; fetch4(jx,j,pos_tex); //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<cutforcesq) {
        numtyp r = ucl_sqrt(rsq);
        numtyp p = r*rdr + (numtyp)1.0;
        int m=p;
        m = MIN(m,nr-1);
        p -= m;
        p = MIN(p,(numtyp)1.0);

        int mtype,index;
        numtyp4 coeff;

        mtype = itype*ntypes+jtype;
        index = type2rhor_z2r[mtype].x*(nr+1)+m;
        fetch4(coeff,index,rhor_sp1_tex);
        numtyp rhoip = (coeff.x*p + coeff.y)*p + coeff.z;

        mtype = jtype*ntypes+itype;
        index = type2rhor_z2r[mtype].x*(nr+1)+m;
        fetch4(coeff,index,rhor_sp1_tex);
        numtyp rhojp = (coeff.x*p + coeff.y)*p + coeff.z;

        mtype = itype*ntypes+jtype;
        index = type2rhor_z2r[mtype].y*(nr+1)+m;
        fetch4(coeff,index,z2r_sp1_tex);
        numtyp z2p = (coeff.x*p + coeff.y)*p + coeff.z;
        fetch4(coeff,index,z2r_sp2_tex);
        numtyp z2 = ((coeff.x*p + coeff.y)*p + coeff.z)*p + coeff.w;

        numtyp recip = ucl_recip(r);
        numtyp phi = z2*recip;
        numtyp phip = z2p*recip - phi*recip;
        numtyp psip;
        fetch(psip,j,fp_tex);
        psip = ifp*rhojp + psip*rhoip + phip;
        numtyp force = -psip*recip;

        f.x+=delx*force;
        f.y+=dely*force;
        f.z+=delz*force;

        if (EVFLAG && eflag) {
          energy += phi;
        }
        if (EVFLAG && vflag) {
          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
  } // if ii
  store_answers_eam(f,energy,virial,ii,inum,tid,t_per_atom,offset,eflag,vflag,
                    ans,engv);
}

__kernel void k_eam_fast(const __global numtyp4 *x_,
                         const __global numtyp *fp_,
                         const __global int2 *type2rhor_z2r_in,
                         const __global numtyp4 *rhor_spline1,
                         const __global numtyp4 *z2r_spline1,
                         const __global numtyp4 *z2r_spline2,
                         const __global int *dev_nbor,
                         const __global int *dev_packed,
                         __global acctyp4 *ans,
                         __global acctyp *engv,
                         const int eflag, const int vflag, const int inum,
                         const int nbor_pitch, const numtyp cutforcesq,
                         const numtyp rdr, const int nr, const int t_per_atom) {
  int tid, ii, offset;
  atom_info(t_per_atom,ii,tid,offset);

  #ifndef ONETYPE
  __local int2 type2rhor_z2r[MAX_SHARED_TYPES*MAX_SHARED_TYPES];
  if (tid<MAX_SHARED_TYPES*MAX_SHARED_TYPES) {
    type2rhor_z2r[tid]=type2rhor_z2r_in[tid];
  }
  __syncthreads();
  #else
  const int oi=ONETYPE*MAX_SHARED_TYPES+ONETYPE;
  const numtyp type2rhor_z2rx=type2rhor_z2r_in[oi].x;
  const numtyp type2rhor_z2ry=type2rhor_z2r_in[oi].y;
  #endif

  int n_stride;
  local_allocate_store_answers_eam();

  acctyp4 f;
  f.x=(acctyp)0; f.y=(acctyp)0; f.z=(acctyp)0;
  acctyp energy, virial[6];
  if (EVFLAG) {
    energy=(acctyp)0;
    for (int i=0; i<6; i++) virial[i]=(acctyp)0;
  }

  if (ii<inum) {
    int nbor, nbor_end;
    int i, numj;
    nbor_info(dev_nbor,dev_packed,nbor_pitch,t_per_atom,ii,offset,i,numj,
              n_stride,nbor_end,nbor);

    numtyp4 ix; fetch4(ix,i,pos_tex); //x_[i];
    numtyp ifp; fetch(ifp,i,fp_tex); //fp_[i];
    #ifndef ONETYPE
    int iw=ix.w;
    int itype=fast_mul((int)MAX_SHARED_TYPES,iw);
    #endif

    for ( ; nbor<nbor_end; nbor+=n_stride) {
      int j=dev_packed[nbor];
      j &= NEIGHMASK;

      numtyp4 jx; fetch4(jx,j,pos_tex); //x_[j];
      #ifndef ONETYPE
      int jw=jx.w;
      int jtype=fast_mul((int)MAX_SHARED_TYPES,jw);
      #endif

      // 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<cutforcesq) {
        numtyp r = ucl_sqrt(rsq);
        numtyp p = r*rdr + (numtyp)1.0;
        int m=p;
        m = MIN(m,nr-1);
        p -= m;
        p = MIN(p,(numtyp)1.0);

        numtyp4 coeff;
        #ifndef ONETYPE
        int mtype;
        #endif
        int index;

        #ifndef ONETYPE
        mtype = itype+jw;
        index = type2rhor_z2r[mtype].x*(nr+1)+m;
        #else
        index = type2rhor_z2rx*(nr+1)+m;
        #endif
        fetch4(coeff,index,rhor_sp1_tex);
        numtyp rhoip = (coeff.x*p + coeff.y)*p + coeff.z;

        #ifndef ONETYPE
        mtype = jtype+iw;
        index = type2rhor_z2r[mtype].x*(nr+1)+m;
        #else
        index = type2rhor_z2rx*(nr+1)+m;
        #endif
        fetch4(coeff,index,rhor_sp1_tex);
        numtyp rhojp = (coeff.x*p + coeff.y)*p + coeff.z;

        #ifndef ONETYPE
        mtype = itype+jw;
        index = type2rhor_z2r[mtype].y*(nr+1)+m;
        #else
        index = type2rhor_z2ry*(nr+1)+m;
        #endif
        fetch4(coeff,index,z2r_sp1_tex);
        numtyp z2p = (coeff.x*p + coeff.y)*p + coeff.z;
        fetch4(coeff,index,z2r_sp2_tex);
        numtyp z2 = ((coeff.x*p + coeff.y)*p + coeff.z)*p + coeff.w;

        numtyp recip = ucl_recip(r);
        numtyp phi = z2*recip;
        numtyp phip = z2p*recip - phi*recip;
        numtyp psip;
        fetch(psip,j,fp_tex);
        psip = ifp*rhojp + psip*rhoip + phip;
        numtyp force = -psip*recip;

        f.x+=delx*force;
        f.y+=dely*force;
        f.z+=delz*force;

        if (EVFLAG && eflag) {
          energy += phi;
        }
        if (EVFLAG && vflag) {
          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
  } // if ii
  store_answers_eam(f,energy,virial,ii,inum,tid,t_per_atom,offset,eflag,vflag,
                    ans,engv);
}