Imported from /home/lorry/working-area/delta_boost-tarball/boost_1_58_0.tar.bz2.HEADboost_1_58_0master

1 files changed, 152 insertions, 0 deletions

diff --git a/libs/endian/example/use_cases.cpp b/libs/endian/example/use_cases.cpp
new file mode 100644
index 000000000..471c633a2
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+++ b/libs/endian/example/use_cases.cpp
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+//  endian/example/uses_cases.cpp  -----------------------------------------------------//
+
+//  Copyright Beman Dawes 2014
+
+//  Distributed under the Boost Software License, Version 1.0.
+//  See http://www.boost.org/LICENSE_1_0.txt
+
+//--------------------------------------------------------------------------------------//
+
+#ifndef _SCL_SECURE_NO_WARNINGS
+# define _SCL_SECURE_NO_WARNINGS
+#endif
+
+#ifndef _CRT_SECURE_NO_WARNINGS
+# define _CRT_SECURE_NO_WARNINGS
+#endif
+
+
+#include <boost/endian/conversion.hpp>
+#include <boost/endian/buffers.hpp>
+#include <boost/endian/arithmetic.hpp>
+#include <iostream>
+
+using namespace boost::endian;
+
+using std::cout;
+using std::endl;
+
+
+
+
+  { // Use case 2 - Endian buffer types
+
+    struct Record
+    {
+      big_ubuf32_t count;  // big endian
+      big_buf32_t  value;  // big endian
+    };
+
+    Record rec;
+
+    read(&rec, sizeof(Record));
+
+    uint32_t count = rec.count.value();
+    int32_t value = rec.value.value();
+
+    ++count;
+    value += fee;
+
+    rec.count = count;
+    rec.value = value;
+
+    write(&rec, sizeof(Record));
+  }
+
+  { // Use case 3a - Endian arithmetic types
+
+    struct Record
+    {
+      big_uint32_t count;  // big endian
+      big_int32_t  value;  // big endian
+    };
+
+    Record rec;
+
+    read(&rec, sizeof(Record));
+
+    ++rec.count;
+    rec.value += fee;
+
+    write(&rec, sizeof(Record));
+  }
+
+  { // Use case 3b - Endian arithmetic types
+
+    struct Record
+    {
+      big_uint32_t count;  // big endian
+      big_int32_t  value;  // big endian
+    };
+
+    Record rec;
+
+    read(&rec, sizeof(Record));
+
+    uint32_t count = rec.count;
+    int32_t value = rec.value;
+
+    ++count;
+    value += fee;
+
+    rec.count = count;
+    rec.value = value;
+
+    write(&rec, sizeof(Record));
+  }
+
+  //  Recommended approach when conversion time is not a concern
+  //
+  //  Conversion time is not a concert with this application because the minimum
+  //  possible number of conversions is performed and because I/O time will be
+  //  much greater than conversion time.
+
+  {
+    struct Record
+    {
+      big_uint32_t count;  // big endian
+      big_int32_t  value;  // big endian
+    };
+
+    Record rec;
+
+    read(&rec, sizeof(Record));
+
+    ++rec.count;
+    rec.value += fee;
+
+    write(&rec, sizeof(Record));
+  }
+
+//  Recommended approach when conversion time is a concern
+  //
+  //  Conversion time is a concert with this application because (1) any conversions
+  //  performed in the loop will consume a great deal of time and because (2) 
+  //  computation time will be much greater than I/O time.
+
+  {
+    struct Record
+    {
+      big_uint32_t count;  // big endian
+      big_int32_t  value;  // big endian
+    };
+
+    Record rec;
+
+    read(&rec, sizeof(Record));
+
+    uint32_t count = rec.count;
+    int32_t value = rec.value;
+
+    for (long long i = 0; i < several_gazillion; ++i)  // (1)
+    {
+      ... immensely complex computation using rec variables many times // (2)
+    }
+
+    rec.count = count;
+    rec.value = value;
+
+    write(&rec, sizeof(Record));
+  }
+
+}