diff --git a/lbmpy/boundaries_in_kernel.py b/lbmpy/boundaries_in_kernel.py
index a1d44c72bde2e3081a6ee8d93bc5afc5eb7fe0ca..a4719be4baa0b5691e8797986d534f5c871d3554 100644
--- a/lbmpy/boundaries_in_kernel.py
+++ b/lbmpy/boundaries_in_kernel.py
@@ -6,8 +6,10 @@ from pystencils.astnodes import LoopOverCoordinate
from pystencils.data_types import cast_func
from pystencils.field import Field
from pystencils.simp.assignment_collection import AssignmentCollection
+from pystencils.simp.simplifications import sympy_cse_on_assignment_list
from pystencils.stencil import inverse_direction
from pystencils.sympyextensions import fast_subs
+from pystencils.astnodes import Block, Conditional
def direction_indices_in_direction(direction, stencil):
@@ -32,29 +34,6 @@ def boundary_substitutions(lb_method):
return replacements
-def transformed_boundary_rule(boundary, accessor, field, direction_symbol, lb_method, **kwargs):
- tmp_field = field.new_field_with_different_name("_tmp")
- rule = boundary(tmp_field, direction_symbol, lb_method, **kwargs)
- bsubs = boundary_substitutions(lb_method)
- rule = [a.subs(bsubs) for a in rule]
- accessor_writes = accessor.write(tmp_field, lb_method.stencil)
- to_replace = set()
- for assignment in rule:
- to_replace.update({fa for fa in assignment.atoms(Field.Access) if fa.field == tmp_field})
-
- def compute_replacement(fa):
- f = fa.index[0]
- shift = accessor_writes[f].offsets
- new_index = tuple(a + b for a, b in zip(fa.offsets, shift))
- return field[new_index](accessor_writes[f].index[0])
-
- substitutions = {fa: compute_replacement(fa) for fa in to_replace}
- all_assignments = [assignment.subs(substitutions) for assignment in rule]
- main_assignments = [a for a in all_assignments if isinstance(a.lhs, Field.Access)]
- sub_expressions = [a for a in all_assignments if not isinstance(a.lhs, Field.Access)]
- return AssignmentCollection(main_assignments, sub_expressions)
-
-
def type_all_numbers(expr, dtype):
substitutions = {a: cast_func(a, dtype) for a in expr.atoms(sp.Number)}
return expr.subs(substitutions)
@@ -83,41 +62,55 @@ def border_conditions(direction, field, ghost_layers=1):
return type_all_numbers(result, loop_ctr.dtype)
-def read_assignments_with_boundaries(collision_rule, pdf_field,
- boundary_spec,
- prev_timestep_accessor,
- current_timestep_accessor):
- method = collision_rule.method
- result = {a: [b, a] for a, b in zip(current_timestep_accessor.read(pdf_field, method.stencil),
- method.pre_collision_pdf_symbols)}
+def transformed_boundary_rule(boundary, accessor_func, field, direction_symbol, lb_method, **kwargs):
+ tmp_field = field.new_field_with_different_name("t")
+ rule = boundary(tmp_field, direction_symbol, lb_method, **kwargs)
+ bsubs = boundary_substitutions(lb_method)
+ rule = [a.subs(bsubs) for a in rule]
+ accessor_writes = accessor_func(tmp_field, lb_method.stencil)
+ to_replace = set()
+ for assignment in rule:
+ to_replace.update({fa for fa in assignment.rhs.atoms(Field.Access) if fa.field == tmp_field})
+
+ def compute_replacement(fa):
+ f = fa.index[0]
+ shift = accessor_writes[f].offsets
+ new_index = tuple(a + b for a, b in zip(fa.offsets, shift))
+ return field[new_index](accessor_writes[f].index[0])
+
+ substitutions = {fa: compute_replacement(fa) for fa in to_replace}
+ all_assignments = [assignment.subs(substitutions) for assignment in rule]
+ main_assignments = [a for a in all_assignments if isinstance(a.lhs, Field.Access)]
+ sub_expressions = [a for a in all_assignments if not isinstance(a.lhs, Field.Access)]
+ assert len(main_assignments) == 1
+ ac = AssignmentCollection(main_assignments, sub_expressions).new_without_subexpressions()
+ return ac.main_assignments[0].rhs
+
+
+def read_assignments_with_boundaries(method, pdf_field, boundary_spec, pre_stream_access, read_access):
+ stencil = method.stencil
+ reads = [Assignment(*v) for v in zip(method.pre_collision_pdf_symbols,
+ read_access(pdf_field, method.stencil))]
for direction, boundary in boundary_spec.items():
dir_indices = direction_indices_in_direction(direction, method.stencil)
border_cond = border_conditions(direction, pdf_field, ghost_layers=1)
for dir_index in dir_indices:
- ac = transformed_boundary_rule(boundary, prev_timestep_accessor, pdf_field, dir_index,
- method, index_field=None)
- assignments = ac.new_without_subexpressions().main_assignments
- assert len(assignments) == 1
- assignment = assignments[0]
- assert assignment.lhs in result
-
- value_without_boundary = result[assignment.lhs][1]
- result[assignment.lhs][1] = sp.Piecewise((assignment.rhs, border_cond),
- (value_without_boundary, True))
+ inv_index = stencil.index(inverse_direction(stencil[dir_index]))
+ value_from_boundary = transformed_boundary_rule(boundary, pre_stream_access, pdf_field, dir_index,
+ method, index_field=None)
+ value_without_boundary = reads[inv_index].rhs
+ new_rhs = sp.Piecewise((value_from_boundary, border_cond),
+ (value_without_boundary, True))
+ reads[inv_index] = Assignment(reads[inv_index].lhs, new_rhs)
- return AssignmentCollection([Assignment(*e) for e in result.values()])
+ return AssignmentCollection(reads)
def update_rule_with_boundaries(collision_rule, input_field, output_field,
- boundaries,
- accessor, prev_accessor=None):
- if prev_accessor is None:
- prev_accessor = accessor
-
- reads = read_assignments_with_boundaries(collision_rule, input_field, boundaries,
- prev_timestep_accessor=prev_accessor,
- current_timestep_accessor=accessor)
+ boundaries, accessor, pre_stream_access):
+ reads = read_assignments_with_boundaries(collision_rule.method, input_field, boundaries,
+ pre_stream_access, accessor.read)
write_substitutions = {}
method = collision_rule.method
@@ -144,3 +137,47 @@ def update_rule_with_boundaries(collision_rule, input_field, output_field,
result.simplification_hints['split_groups'] = new_split_groups
return result
+
+
+def boundary_conditional(boundary, direction, read_of_next_accessor, lb_method, output_field, cse=False, **kwargs):
+ stencil = lb_method.stencil
+ tmp_field = output_field.new_field_with_different_name("t")
+
+ dir_indices = direction_indices_in_direction(direction, stencil)
+
+ assignments = []
+ for direction_idx in dir_indices:
+ rule = boundary(tmp_field, direction_idx, lb_method, **kwargs)
+ boundary_subs = boundary_substitutions(lb_method)
+ rule = [a.subs(boundary_subs) for a in rule]
+
+ rhs_substitutions = {tmp_field(i): sym for i, sym in enumerate(lb_method.post_collision_pdf_symbols)}
+ offset = stencil[direction_idx]
+ inv_offset = inverse_direction(offset)
+ inv_idx = stencil.index(inv_offset)
+
+ lhs_substitutions = {
+ tmp_field[offset](inv_idx): read_of_next_accessor(output_field, stencil)[inv_idx]}
+ rule = [Assignment(a.lhs.subs(lhs_substitutions), a.rhs.subs(rhs_substitutions)) for a in rule]
+ ac = AssignmentCollection([rule[-1]], rule[:-1]).new_without_subexpressions()
+ assignments += ac.main_assignments
+
+ border_cond = border_conditions(direction, output_field, ghost_layers=1)
+ if cse:
+ assignments = sympy_cse_on_assignment_list(assignments)
+ return Conditional(border_cond, Block(assignments))
+
+
+def update_rule_with_push_boundaries(collision_rule, field, boundary_spec, accessor, read_of_next_accessor):
+ if 'split_groups' in collision_rule.simplification_hints:
+ raise NotImplementedError("Split is not supported yet")
+ method = collision_rule.method
+ loads = [Assignment(a, b) for a, b in zip(method.pre_collision_pdf_symbols, accessor.read(field, method.stencil))]
+ stores = [Assignment(a, b) for a, b in
+ zip(accessor.write(field, method.stencil), method.post_collision_pdf_symbols)]
+
+ result = loads + collision_rule.all_assignments + stores
+ for direction, boundary in boundary_spec.items():
+ cond = boundary_conditional(boundary, direction, read_of_next_accessor, method, field)
+ result.append(cond)
+ return result
\ No newline at end of file