add GPU device query functions to library interface and its wrappers

doc/src/Library_config.rst

@@ -15,6 +15,8 @@ This section documents the following functions:
 - :cpp:func:`lammps_config_package_count`
 - :cpp:func:`lammps_config_package_name`
 - :cpp:func:`lammps_config_accelerator`
+- :cpp:func:`lammps_has_gpu_device`
+- :cpp:func:`lammps_gpu_device_info`
 - :cpp:func:`lammps_has_style`
 - :cpp:func:`lammps_style_count`
 - :cpp:func:`lammps_style_name`
@@ -132,6 +134,16 @@ approach.
 
 -----------------------
 
+.. doxygenfunction:: lammps_has_gpu_device
+   :project: progguide
+
+-----------------------
+
+.. doxygenfunction:: lammps_get_gpu_device_info
+   :project: progguide
+
+-----------------------
+
 .. doxygenfunction:: lammps_has_style
    :project: progguide
 

python/lammps/core.py

@@ -281,6 +281,7 @@ class lammps(object):
     self.lib.lammps_version.argtypes = [c_void_p]
 
     self.lib.lammps_get_os_info.argtypes = [c_char_p, c_int]
+    self.lib.lammps_get_gpu_device_info.argtypes = [c_char_p, c_int]
 
     self.lib.lammps_get_mpi_comm.argtypes = [c_void_p]
 
@@ -490,7 +491,7 @@ class lammps(object):
 
     sb = create_string_buffer(512)
     self.lib.lammps_get_os_info(sb,512)
-    return sb
+    return sb.value.decode()
 
   # -------------------------------------------------------------------------
 
@@ -1552,6 +1553,37 @@ class lammps(object):
 
   # -------------------------------------------------------------------------
 
+  @property
+  def has_gpu_device(self):
+    """ Availability of GPU package compatible device
+
+    This is a wrapper around the :cpp:func:`lammps_has_gpu_device`
+    function of the C library interface.
+
+    :return: True if a GPU package compatible device is present, otherwise False
+    :rtype: bool
+    """
+    return self.lib.lammps_has_gpu_device() != 0
+
+  # -------------------------------------------------------------------------
+
+  def get_gpu_device_info(self):
+    """Return a string with detailed information about any devices that are
+    usable by the GPU package.
+
+    This is a wrapper around the :cpp:func:`lammps_get_gpu_device_info` 
+    function of the C-library interface. 
+
+    :return: GPU device info string
+    :rtype:  string
+    """
+
+    sb = create_string_buffer(8192)
+    self.lib.lammps_get_gpu_device_info(sb,8192)
+    return sb.value.decode()
+
+  # -------------------------------------------------------------------------
+
   @property
   def installed_packages(self):
     """ List of the names of enabled packages in the LAMMPS shared library

src/library.cpp

@@ -4111,8 +4111,10 @@ int lammps_version(void *handle)
 The :cpp:func:`lammps_get_os_info` function can be used to retrieve
 detailed information about the hosting operating system and
 compiler/runtime.
+
 A suitable buffer for a C-style string has to be provided and its length.
-If the assembled text will be truncated to not overflow this buffer.
+The assembled text will be truncated to not overflow this buffer. The
+string is typically a few hundred bytes long.
 
 .. versionadded:: 9Oct2020
 
@@ -4339,6 +4341,60 @@ int lammps_config_accelerator(const char *package,
   return Info::has_accelerator_feature(package,category,setting) ? 1 : 0;
 }
 
+/** Check for presence of a viable GPU package device
+ *
+\verbatim embed:rst
+
+The :cpp:func:`lammps_has_gpu_device` function checks at runtime if
+an accelerator device is present that can be used with the
+:doc:`GPU package <Speed_gpu>`. If at least one suitable device is
+present the function will return 1, otherwise 0.
+
+More detailed information about the available device or devices can
+be obtained by calling the
+:cpp:func:`lammps_get_gpu_device_info` function.
+
+.. versionadded:: 14May2021
+
+\endverbatim
+ *
+ * \return  1 if viable device is available, 0 if not.  */
+
+int lammps_has_gpu_device()
+{
+  return Info::has_gpu_device() ? 1: 0;
+}
+
+/** Get GPU package device information
+ *
+\verbatim embed:rst
+
+The :cpp:func:`lammps_get_gpu_device_info` function can be used to retrieve
+detailed information about any accelerator devices that are viable for use
+with the :doc:`GPU package <Speed_gpu>`.  It will produce a string that is
+equivalent to the output of the ``nvc_get_device`` or ``ocl_get_device`` or
+``hip_get_device`` tools that are compiled alongside LAMMPS if the GPU
+package is enabled.
+
+A suitable buffer for a C-style string has to be provided and its length.
+The assembled text will be truncated to not overflow this buffer.  This
+string can be several kilobytes long, if multiple devices are present.
+
+.. versionadded:: 14May2021
+
+\endverbatim
+ *
+ * \param  buffer    string buffer to copy the information to
+ * \param  buf_size  size of the provided string buffer */
+
+void lammps_get_gpu_device_info(char *buffer, int buf_size)
+{
+  if (buf_size <= 0) return;
+  buffer[0] = buffer[buf_size-1] = '\0';
+  std::string devinfo = Info::get_gpu_device_info();
+  strncpy(buffer, devinfo.c_str(), buf_size-1);
+}
+
 /* ---------------------------------------------------------------------- */
 
 /** Check if a specific style has been included in LAMMPS

src/library.h

@@ -196,6 +196,8 @@ int lammps_config_package_count();
 int lammps_config_package_name(int, char *, int);
 
 int lammps_config_accelerator(const char *, const char *, const char *);
+int lammps_has_gpu_device();
+void lammps_get_gpu_device_info(char *buffer, int buf_size);
 
 int lammps_has_style(void *, const char *, const char *);
 int lammps_style_count(void *, const char *);

tools/swig/lammps.i

@@ -116,6 +116,8 @@ extern int    lammps_config_has_package(const char *);
 extern int    lammps_config_package_count();
 extern int    lammps_config_package_name(int, char *, int);
 extern int    lammps_config_accelerator(const char *, const char *, const char *);
+extern int    lammps_has_gpu_device();
+extern void   lammps_get_gpu_device_info(char *buffer, int buf_size);
 extern int    lammps_has_style(void *, const char *, const char *);
 extern int    lammps_style_count(void *, const char *);
 extern int    lammps_style_name(void *, const char *, int, char *buffer, int buf_size);
@@ -236,6 +238,8 @@ extern int    lammps_config_has_package(const char *);
 extern int    lammps_config_package_count();
 extern int    lammps_config_package_name(int, char *, int);
 extern int    lammps_config_accelerator(const char *, const char *, const char *);
+extern int    lammps_has_gpu_device();
+extern void   lammps_get_gpu_device_info(char *buffer, int buf_size);
 extern int    lammps_has_style(void *, const char *, const char *);
 extern int    lammps_style_count(void *, const char *);
 extern int    lammps_style_name(void *, const char *, int, char *buffer, int buf_size);