From bc38a8fbd654cce8431a0fd720ca57a073ba050d Mon Sep 17 00:00:00 2001
From: Axel Huebl <axel.huebl@plasma.ninja>
Date: Mon, 5 Apr 2021 14:04:43 -0700
Subject: Parser: Bessel Function (J_n) (#1854)

* Parser: Bessel Function (J_n)

Add the Bessel Function of the First Kind (J_n) to the parser.

* Parser: regenerate

* Parser: No jn for DPC++ (yet)

* Parser: no jnf for Apple

At least on AppleClang and also seen in flang source-code, we
just call the double variant of `jn` instead of using a specialized
call to `jnf`.

This might be less efficient than needed with Intel on Apple, but
I don't have a system to test this on at the moment and this is thus
a save bet for compile stability.

Co-authored-by: Tools <warpx@lbl.gov>
---
 Source/Parser/wp_parser_y.h | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

(limited to 'Source/Parser/wp_parser_y.h')

diff --git a/Source/Parser/wp_parser_y.h b/Source/Parser/wp_parser_y.h
index 1a66ac944..8a8aec89b 100644
--- a/Source/Parser/wp_parser_y.h
+++ b/Source/Parser/wp_parser_y.h
@@ -7,13 +7,14 @@
 #include <AMReX_Math.H>
 #include <AMReX_Print.H>
 
+#include <cmath>
 #include <cstdlib>
 #include <cstdio>
 #include <cstring>
 #include <iostream>
 #include <type_traits>
 
-enum wp_f1_t {  // Bulit-in functions with one argument
+enum wp_f1_t {  // Built-in functions with one argument
     WP_SQRT = 1,
     WP_EXP,
     WP_LOG,
@@ -47,6 +48,7 @@ enum wp_f2_t {  // Built-in functions with two arguments
     WP_AND,
     WP_OR,
     WP_HEAVISIDE,
+    WP_JN,
     WP_MIN,
     WP_MAX
 };
@@ -237,6 +239,20 @@ wp_call_f2 (enum wp_f2_t type, T a, T b)
         return ((a != T(0)) || (b != T(0))) ? 1.0 : 0.0;
     case WP_HEAVISIDE:
         return (a < 0.0) ? amrex::Real(0.0) : ((a > 0.0) ? amrex::Real(1.0) : b);
+    case WP_JN:
+#ifdef AMREX_USE_DPCPP
+        // neither jn(f) nor std::cyl_bessel_j work yet
+        // https://github.com/oneapi-src/oneAPI-spec/issues/308
+        AMREX_DEVICE_PRINTF("wp_call_f2: Parser does not implement jn (%d) for SYCL/DPC++ yet\n", type);
+        amrex::Abort();
+        return 0.0;
+#else
+#   if defined(AMREX_USE_FLOAT) && !defined(__APPLE__)
+        return jnf(a, b);
+#   else
+        return jn(a, b);
+#   endif
+#endif
     case WP_MIN:
         return (a < b) ? a : b;
     case WP_MAX:
-- 
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