From 94b387f58973b1b35512defd0fc18e520a4433cb Mon Sep 17 00:00:00 2001
From: Kaushik Kulkarni <kaushikcfd@gmail.com>
Date: Tue, 1 Mar 2022 00:21:13 -0600
Subject: [PATCH] Implements CWithGNULibCTarget

---
 loopy/__init__.py          |  5 ++-
 loopy/target/c/__init__.py | 72 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/loopy/__init__.py b/loopy/__init__.py
index 0e6e9f87c..1f61c7719 100644
--- a/loopy/__init__.py
+++ b/loopy/__init__.py
@@ -149,7 +149,9 @@ from loopy.frontend.fortran import (c_preprocess, parse_transformed_fortran,
         parse_fortran)
 
 from loopy.target import TargetBase, ASTBuilderBase
-from loopy.target.c import CFamilyTarget, CTarget, ExecutableCTarget, generate_header
+from loopy.target.c import (CFamilyTarget, CTarget, ExecutableCTarget,
+                            generate_header, CWithGNULibcTarget,
+                            ExecutableCWithGNULibcTarget)
 from loopy.target.cuda import CudaTarget
 from loopy.target.opencl import OpenCLTarget
 from loopy.target.pyopencl import PyOpenCLTarget
@@ -296,6 +298,7 @@ __all__ = [
 
         "TargetBase",
         "CFamilyTarget", "CTarget", "ExecutableCTarget", "generate_header",
+        "CWithGNULibcTarget", "ExecutableCWithGNULibcTarget",
         "CudaTarget", "OpenCLTarget",
         "PyOpenCLTarget", "ISPCTarget",
         "NumbaTarget", "NumbaCudaTarget",
diff --git a/loopy/target/c/__init__.py b/loopy/target/c/__init__.py
index 0058ad47f..3457b8e7e 100644
--- a/loopy/target/c/__init__.py
+++ b/loopy/target/c/__init__.py
@@ -677,6 +677,49 @@ class CMathCallable(ScalarCallable):
             }}""")
 
 
+class GNULibcCallable(ScalarCallable):
+    def with_types(self, arg_id_to_dtype, callables_table):
+        name = self.name
+
+        if name in ["bessel_jn", "bessel_yn"]:
+            # bessel functions
+            # https://www.gnu.org/software/libc/manual/html_node/Special-Functions.html
+            for id in arg_id_to_dtype:
+                if not -1 <= id <= 1:
+                    raise LoopyError(f"'{name}' can take exactly 2 arguments.")
+
+            if (not arg_id_to_dtype.get(0)) or (not arg_id_to_dtype.get(1)):
+                # the types provided aren't mature enough to specialize the
+                # callable
+                return (
+                        self.copy(arg_id_to_dtype=arg_id_to_dtype),
+                        callables_table)
+
+            if not arg_id_to_dtype[0].is_integral():
+                raise LoopyTypeError(f"'{name}' needs order to be an int-type.")
+
+            if arg_id_to_dtype[1].numpy_dtype == np.float32:
+                name_in_target = name[-2:]+"f"
+            elif arg_id_to_dtype[1].numpy_dtype == np.float64:
+                name_in_target = name[-2:]
+            else:
+                raise LoopyTypeError("argument to bessel function must be f32,"
+                                     f"f64, got {arg_id_to_dtype[1].numpy_dtype}.")
+
+            return (
+                    self.copy(name_in_target=name_in_target,
+                              arg_id_to_dtype={-1: arg_id_to_dtype[1],
+                                               0: NumpyType(np.int32),
+                                               1: arg_id_to_dtype[1]}),
+                    callables_table)
+        else:
+            raise NotImplementedError(f"with_types for '{name}'")
+
+    def generate_preambles(self, target):
+        if self.name in ["bessel_yn", "bessel_jn"]:
+            yield("08_c_math", "#include <math.h>")
+
+
 def get_c_callables():
     """
     Returns an instance of :class:`InKernelCallable` if the function
@@ -690,6 +733,13 @@ def get_c_callables():
 
     return {id_: CMathCallable(id_) for id_ in cmath_ids}
 
+
+def get_gnu_libc_callables():
+    # Support special functions from
+    # https://www.gnu.org/software/libc/manual/html_node/Special-Functions.html
+    func_ids = ["bessel_jn", "bessel_yn"]
+    return {id_: GNULibcCallable(id_) for id_ in func_ids}
+
 # }}}
 
 
@@ -1317,4 +1367,26 @@ class ExecutableCTarget(CTarget):
 
 # }}}
 
+
+# {{{ C99 (with GNULibc) callable target
+
+class CWithGNULibcTarget(CTarget):
+    def get_device_ast_builder(self):
+        return CWithGNULibcASTBuilder(self)
+
+
+class CWithGNULibcASTBuilder(CASTBuilder):
+    @property
+    def known_callables(self):
+        callables = super().known_callables
+        callables.update(get_gnu_libc_callables())
+        return callables
+
+
+class ExecutableCWithGNULibcTarget(ExecutableCTarget):
+    def get_device_ast_builder(self):
+        return CWithGNULibcASTBuilder(self)
+
+# }}}
+
 # vim: foldmethod=marker
-- 
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