From 5bf8e1bc5b249a14ed5dd0a4cbb294fb2b3a3c1d Mon Sep 17 00:00:00 2001
From: Axel Kohlmeyer <akohlmey@gmail.com>
Date: Thu, 19 Apr 2018 18:37:15 -0400
Subject: [PATCH] add ability to retrieve the number of local rows for computes
returning local data
this is done supporting the combination of type == 2 with style == 0,
i.e. a local scalar, which is not available in C++ (but there one can
access the compute style data member directly. for the python interface,
the pointer is automatically dereferenced and returned as a c_int.
---
python/lammps.py | 11 ++++++++---
src/library.cpp | 10 +++++++++-
2 files changed, 17 insertions(+), 4 deletions(-)
diff --git a/python/lammps.py b/python/lammps.py
index f5f252c45c..417427eb4b 100644
--- a/python/lammps.py
+++ b/python/lammps.py
@@ -384,9 +384,14 @@ class lammps(object):
ptr = self.lib.lammps_extract_compute(self.lmp,id,style,type)
return ptr
if type == 2:
- self.lib.lammps_extract_compute.restype = POINTER(POINTER(c_double))
- ptr = self.lib.lammps_extract_compute(self.lmp,id,style,type)
- return ptr
+ if style == 0:
+ self.lib.lammps_extract_compute.restype = POINTER(c_int)
+ ptr = self.lib.lammps_extract_compute(self.lmp,id,style,type)
+ return ptr[0]
+ else:
+ self.lib.lammps_extract_compute.restype = POINTER(POINTER(c_double))
+ ptr = self.lib.lammps_extract_compute(self.lmp,id,style,type)
+ return ptr
return None
# extract fix info
diff --git a/src/library.cpp b/src/library.cpp
index 07c4cae9c1..b7a0c0b5be 100644
--- a/src/library.cpp
+++ b/src/library.cpp
@@ -480,10 +480,13 @@ void *lammps_extract_atom(void *ptr, char *name)
compute's internal data structure for the entity
caller should cast it to (double *) for a scalar or vector
caller should cast it to (double **) for an array
- for per-atom or local data, returns a pointer to the
+ for per-atom or local vector/array data, returns a pointer to the
compute's internal data structure for the entity
caller should cast it to (double *) for a vector
caller should cast it to (double **) for an array
+ for local data, accessing scalar data for the compute (type = 0),
+ returns a pointer that should be cast to (int *) which points to
+ an int with the number of local rows, i.e. the length of the local array.
returns a void pointer to the compute's internal data structure
for the entity which the caller can cast to the proper data type
returns a NULL if id is not recognized or style/type not supported
@@ -541,6 +544,11 @@ void *lammps_extract_compute(void *ptr, char *id, int style, int type)
if (style == 2) {
if (!compute->local_flag) return NULL;
+ if (type == 0) {
+ if (compute->invoked_local != lmp->update->ntimestep)
+ compute->compute_local();
+ return (void *) &compute->size_local_rows;
+ }
if (type == 1) {
if (compute->invoked_local != lmp->update->ntimestep)
compute->compute_local();
--
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