From 38ab140ab63c2ce27b8d78181035bca1167e932c Mon Sep 17 00:00:00 2001
From: Steven Franke <s.j.franke@icloud.com>
Date: Tue, 28 Mar 2017 12:16:34 +0000
Subject: [PATCH] Thanks Bill.

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7622 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
---
 lib/crc.f90   | 20 ++++++++++++++++++++
 lib/crc12.cpp | 20 ++++++++++++++++++++
 2 files changed, 40 insertions(+)
 create mode 100644 lib/crc.f90
 create mode 100644 lib/crc12.cpp

diff --git a/lib/crc.f90 b/lib/crc.f90
new file mode 100644
index 000000000..8ac68e051
--- /dev/null
+++ b/lib/crc.f90
@@ -0,0 +1,20 @@
+module crc 
+  use, intrinsic :: iso_c_binding, only: c_int, c_loc, c_int8_t, c_bool, c_short
+  interface
+    function crc12 (data, length) bind (C, name="crc12")
+      use, intrinsic :: iso_c_binding, only: c_short, c_ptr, c_int
+      implicit none
+      integer (c_short) :: crc12
+      type (c_ptr), value :: data
+      integer (c_int), value :: length
+    end function crc12
+ 
+    function crc12_check (data, length) bind (C, name="crc12_check")
+      use, intrinsic :: iso_c_binding, only: c_bool, c_ptr, c_int
+      implicit none
+      logical (c_bool) :: crc12_check
+      type (c_ptr), value :: data
+      integer (c_int), value :: length
+    end function crc12_check
+  end interface
+end module crc
diff --git a/lib/crc12.cpp b/lib/crc12.cpp
new file mode 100644
index 000000000..7077aaba7
--- /dev/null
+++ b/lib/crc12.cpp
@@ -0,0 +1,20 @@
+#include <boost/crc.hpp>
+#include <boost/cstdint.hpp>
+
+extern "C"
+{
+   short crc12 (unsigned char const * data, int length);
+   bool crc12_check (unsigned char const * data, int length);
+}
+
+// assumes CRC is last 16 bits of the data and is set to zero
+// caller should assign the returned CRC into the message in big endian byte order
+short crc12 (unsigned char const * data, int length)
+{
+    return boost::augmented_crc<12, 0xc06> (data, length);
+}
+
+bool crc12_check (unsigned char const * data, int length)
+{
+   return !boost::augmented_crc<12, 0xc06> (data, length);
+}