From d3961b8ed4945c63e6b72c887b68fc543ef72e0e Mon Sep 17 00:00:00 2001
From: "Jeroen T. Vermeulen" <jtvjtv@gmail.com>
Date: Sun, 18 Sep 2016 21:10:28 +0200
Subject: [PATCH] Replace cpucount.c with cpucount.cpp.

Uses a new function in C++11.  Avoids platform-specific code.
---
 tools/cpucount.c       | 103 -----------------------------------------
 tools/cpucount.cpp     |  11 +++++
 tools/get_cpu_count.sh |  35 ++++++++++++--
 3 files changed, 41 insertions(+), 108 deletions(-)
 delete mode 100644 tools/cpucount.c
 create mode 100644 tools/cpucount.cpp

diff --git a/tools/cpucount.c b/tools/cpucount.c
deleted file mode 100644
index 3f06b8b..0000000
--- a/tools/cpucount.c
+++ /dev/null
@@ -1,103 +0,0 @@
-/***********************************************************************
- *  OSXCross                                                           *
- *  Copyright (C) 2013-2016 by Thomas Poechtrager                      *
- *  t.poechtrager@gmail.com                                            *
- *                                                                     *
- *  This program is free software; you can redistribute it and/or      *
- *  modify it under the terms of the GNU General Public License        *
- *  as published by the Free Software Foundation; either version 2     *
- *  of the License, or (at your option) any later version.             *
- *                                                                     *
- *  This program is distributed in the hope that it will be useful,    *
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of     *
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the      *
- *  GNU General Public License for more details.                       *
- *                                                                     *
- *  You should have received a copy of the GNU General Public License  *
- *  along with this program; if not, write to the Free Software        *
- *  Foundation, Inc.,                                                  *
- *  51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.      *
- ***********************************************************************/
-
-#include <stdio.h>
-#include <stdlib.h>
-
-#ifdef __CYGWIN__
-#define WIN32
-#endif /* __CYGWIN__ */
-
-#ifdef WIN32
-#include <windows.h>
-#endif /* WIN32 */
-
-#ifdef __linux__
-#define __USE_GNU
-#include <sched.h>
-#undef __USE_GNU
-#endif /* __linux__ */
-
-#if defined(__FreeBSD__) || defined(__NetBSD__) || \
-    defined(__OpenBSD__) || defined(__DragonFly__) || \
-    defined(__APPLE__)
-#include <unistd.h>
-#include <sys/param.h>
-#include <sys/types.h>
-#include <sys/sysctl.h>
-
-#ifndef HW_AVAILCPU
-#define HW_AVAILCPU 25
-#endif /* HW_AVAILCPU */
-#endif /* BSD */
-
-int getcpucount() {
-#ifdef WIN32
-  SYSTEM_INFO sysinfo;
-  GetSystemInfo(&sysinfo);
-
-  return sysinfo.dwNumberOfProcessors;
-#else
-#ifdef __linux__
-  cpu_set_t cs;
-  int i, cpucount = 0;
-
-  CPU_ZERO(&cs);
-
-  if (sched_getaffinity(0, sizeof(cs), &cs))
-    return 1;
-
-  for (i = 0; i < CPU_SETSIZE; i++)
-    if (CPU_ISSET(i, &cs))
-      cpucount++;
-
-  return cpucount;
-#else
-#if defined(__FreeBSD__) || defined(__NetBSD__) || \
-    defined(__OpenBSD__) || defined(__DragonFly__) || \
-    defined(__APPLE__)
-  int cpucount = 0;
-  int mib[4];
-  size_t len = sizeof(cpucount);
-
-  mib[0] = CTL_HW;
-  mib[1] = HW_AVAILCPU;
-
-  sysctl(mib, 2, &cpucount, &len, NULL, 0);
-
-  if (cpucount < 1) {
-    mib[1] = HW_NCPU;
-    sysctl(mib, 2, &cpucount, &len, NULL, 0);
-  }
-
-  return cpucount ? cpucount : 1;
-#else
-#warning unknown platform
-  return 1;
-#endif /* BSD */
-#endif /* __linux__ */
-#endif /* WIN32 */
-}
-
-int main(void) {
-  printf("%d\n", getcpucount());
-  return 0;
-}
diff --git a/tools/cpucount.cpp b/tools/cpucount.cpp
new file mode 100644
index 0000000..91c2343
--- /dev/null
+++ b/tools/cpucount.cpp
@@ -0,0 +1,11 @@
+#include <iostream>
+#include <thread>
+
+/** Print number of (enabled) CPU cores.
+ *
+ * Requires C++11 or better.
+ */
+int main()
+{
+    std::cout << std::thread::hardware_concurrency() << std::endl;
+}
diff --git a/tools/get_cpu_count.sh b/tools/get_cpu_count.sh
index adb579a..a8b3972 100755
--- a/tools/get_cpu_count.sh
+++ b/tools/get_cpu_count.sh
@@ -1,18 +1,43 @@
 #!/usr/bin/env bash
 
 set -e
+set -u
 
-which cc &>/dev/null || { echo "1" && exit 0; }
+# Print number of enabled CPUs.  Use this as a simple, platform-independent
+# replacement for nproc or ncpus.
+#
+# The shell script wraps a simple C++ tool which will be compiled on demand.
 
-prog="cpucount"
 
-pushd "${0%/*}" >/dev/null 2>&1
+# This script's location.  The proper way to do this in bash is using
+# ${BASH_SOURCE[0]}; ignore the possibility of softlinks.
+script_dir=$(cd $(dirname ${BASH_SOURCE[0]}) && pwd)
 
+prog="$script_dir/cpucount"
 case "$(uname -s)" in
   *NT* | CYGWIN*)
     prog="${prog}.exe" ;;
 esac
 
-[ ! -f $prog ] && cc cpucount.c -o cpucount &>/dev/null
+if [ ! -f $prog ]
+then
+    # Don't have cpucount.  Build it.
 
-./$prog
+    if ! which c++ >/dev/null
+    then
+        # Can't compile cpucount.  Just give the safe answer.
+        echo 1
+        exit 0
+    fi
+
+    # Attempt to compile cpucount.cpp.
+    if ! c++ $prog.cpp -o $prog &>/dev/null
+    then
+        # Okay, that didn't work...  Try it with gcc/clang's option to force
+        # C++11.  Versions of gcc older than 6.x still default to C++98.
+        c++ $prog.cpp -std=c++11 -o $prog >/dev/null
+    fi
+fi
+
+# Now, at last: run cpucount.
+$prog