#define THECELL {{ thecell }}

{# ---------------- macro to generate code computing pressure top-down ---------------
   formula = formula to compute 'gravitational' mass
   = rhodz (dry) rhodz*theta (boussinesq) rhodz*(1+qv) (moist)         #}

#define BALANCE(formula) {% call(thecell) balance() %} formula {% endcall %}
{% macro balance() %} {% set formula=caller %}
SEQUENCE_EXT
  PROLOGUE(llm)
    pk(CELL) = ptop + .5*g*{{ formula('CELL') }}
  END_BLOCK
  BODY('llm-1,1,-1') 
    pk(CELL) = pk(UP(CELL)) + (.5*g)*({{ formula('CELL') }}+{{ formula('UP(CELL)') }})
  END_BLOCK
  IF(caldyn_eta == eta_lag) THEN
    EPILOGUE(1)
      ps(HIDX(CELL)) = pk(CELL) + .5*g*{{ formula('CELL') }}
    END_BLOCK
  END IF
END_BLOCK
{%- endmacro %}

{# ------------ macro to generate code computing geopotential bottom-up --------------
   var = variable to be stored in pk(CELL)
   caller() computes gv = g*v where v = specific volume
   details depend on caldyn_thermo #}

#define GEOPOT(var) {% call geopot(var) %}
{% macro geopot(var) %} {% set formula=caller %}
  SEQUENCE_EXT
    BODY('1,llm')
      p_ik = pk(CELL)
      {{ formula() }}
      pk(CELL) = {{ var }}
      geopot(UP(CELL)) = geopot(CELL) + gv*rhodz(CELL)
    END_BLOCK
  END_BLOCK
{%- endmacro %}

#define END_GEOPOT {% endcall %}

KERNEL(compute_geopot)
  SELECT CASE(caldyn_thermo)
  CASE(thermo_boussinesq)
    ! use hydrostatic balance with theta*rhodz to find pk (=Lagrange multiplier=pressure)
    BALANCE( theta(THECELL,1)*rhodz(THECELL) )
    ! now pk contains the Lagrange multiplier (pressure)
    ! specific volume 1 = dphi/g/rhodz
    SEQUENCE_EXT
      BODY('1,llm')
        geopot(UP(CELL)) = geopot(CELL) + g*rhodz(CELL)
      END_BLOCK
    END_BLOCK
  CASE(thermo_theta)
    BALANCE( rhodz(THECELL) )
    GEOPOT('exner_ik')
      exner_ik = cpp * (p_ik/preff) ** kappa
      gv = (g*kappa)*theta(CELL,1)*exner_ik/p_ik
    END_GEOPOT
  CASE(thermo_entropy)
    BALANCE( rhodz(THECELL) )
    GEOPOT('temp_ik')
      temp_ik = Treff*exp((theta(CELL,1) + Rd*log(p_ik/preff))/cpp)
      gv = (g*Rd)*temp_ik/p_ik   ! specific volume v = Rd*T/p
    END_GEOPOT
  CASE(thermo_moist)
    BALANCE( rhodz(THECELL)*(1.+theta(THECELL,2)) )
    GEOPOT('temp_ik')
      qv = theta(CELL,2) ! water vaper mixing ratio = mv/md
      Rmix = Rd+qv*Rv
      chi = ( theta(CELL,1) + Rmix*log(p_ik/preff) ) / (cpp + qv*cppv) ! log(T/Treff)
      temp_ik = Treff*exp(chi)
      ! specific volume v = R*T/p
      ! R = (Rd + qv.Rv)/(1+qv)
      gv = g*Rmix*temp_ik/(p_ik*(1+qv))
    END_GEOPOT
  END SELECT
END_BLOCK

KERNEL(caldyn_slow_hydro)
  FORALL_CELLS_EXT()
    ON_EDGES
      uu = .5*(rhodz(CELL1)+rhodz(CELL2))*u(EDGE)
      hflux(EDGE) = uu*LE_DE
    END_BLOCK
  END_BLOCK

  FORALL_CELLS()
    ON_PRIMAL
      ke=0.d0
      FORALL_EDGES
        ke = ke + LE_DE*u(EDGE)**2
      END_BLOCK
      BERNI(CELL)=ke*(.25/AI)
    END_BLOCK
  END_BLOCK
  IF(zero) THEN
    FORALL_CELLS()
      ON_EDGES
        du(EDGE) = SIGN*(berni(CELL1)-berni(CELL2)) ! minus gradient
      END_BLOCK
    END_BLOCK
  ELSE
    FORALL_CELLS()
      ON_EDGES
        du(EDGE) = du(EDGE) + SIGN*(berni(CELL1)-berni(CELL2)) ! minus gradient
      END_BLOCK
    END_BLOCK
  END IF

END_BLOCK