Reimplement Oracle NUMBER to/from C++ integer type conversions

The implementation has been moved to the details namespace. Signed and
unsigned 32 bit versions, as well as an unsigned 64 bit version have also
been added.

1 files changed, 264 insertions, 0 deletions

diff --git a/odb/oracle/details/number.cxx b/odb/oracle/details/number.cxx
new file mode 100644
index 0000000..bf7902a
--- /dev/null
+++ b/odb/oracle/details/number.cxx
@@ -0,0 +1,264 @@
+// file      : odb/oracle/details/number.cxx
+// author    : Constantin Michael <constantin@codesynthesis.com>
+// copyright : Copyright (c) 2005-2011 Code Synthesis Tools CC
+// license   : GNU GPL v2; see accompanying LICENSE file
+
+#include <cstddef>  // std::size_t
+#include <cassert>
+
+#include <odb/oracle/details/number.hxx>
+
+using namespace std;
+
+namespace odb
+{
+  namespace oracle
+  {
+    namespace details
+    {
+      // The VARNUM type's binary representation is made up of the following
+      // bit fields, ordered in increasing memory address.
+      //
+      // 000 to 007: The size of the binary representation, including the
+      //             exponent bits and the mantissa bits, but excluding these
+      //             length bits.
+      //
+      // 008 to 015: The base-100 exponent bits. The most significant bit is
+      //             the sign bit of the number, which is set for positive
+      //             numbers and cleared for negative numbers. For positive
+      //             numbers, the exponent has a bias of 65 added to it.
+      //
+      // 016 to 175: The mantissa bits. Each byte of this field represents a
+      //             single base-100 value.
+      //
+      //
+
+      long long
+      number_to_int64 (const unsigned char* b)
+      {
+        int n (b[0]);
+
+        // Zero is represented by zero significant bits and an exponent
+        // set to 128.
+        //
+        if (n == 1)
+        {
+          assert (b[1] == 128);
+          return 0;
+        }
+
+        long long v (0);
+
+        // Test the sign bit of the exponent.
+        //
+        if (b[1] & 0x80)
+        {
+
+          // The unbiased exponent of a positive number may be calculated as
+          // b[1] - 128 - 65. For an integer, this is the order of magnitude
+          // of the number. Calculate the maximum weight, 100 ^ o, where o is
+          // the order of magnitude of the number.
+          //
+          long long w (1);
+
+          for (size_t i (0), o (b[1] - 193); i < o; ++i)
+            w *= 100;
+
+          // Accumlate the sum of the significant base-100 terms.
+          //
+          for (const unsigned char* m (b + 2), *e (b + 1 + n); m < e; ++m)
+          {
+            v += (*m - 1) * w;
+            w /= 100;
+          }
+        }
+        else
+        {
+          // The unbiased exponent of a negative number is calculated as
+          // (~b[1] & 0x7F) - 193. For an integer, this is the order of
+          // magnitude of the number. Calculate the maximum weight, 100 ^ o,
+          // where o is the order of magnitude of the number.
+          //
+          long long w (1);
+
+          for (size_t i (0), o ((~b[1] & 0x7F) - 65); i < o; ++i)
+            w *= 100;
+
+          // Accumulate the sum of the significant base-100 terms. Note that
+          // negative values will have a terminator byte which is included
+          // in the length. This is ignored.
+          //
+          for (const unsigned char* m (b + 2), *e (b + n); m < e; ++m)
+          {
+            v -= (101 - *m) * w;
+            w /= 100;
+          }
+        }
+
+        return v;
+      }
+
+      void
+      int64_to_number (unsigned char* b, long long v)
+      {
+        // We assume that b is long enough to contain a long long VARNUM
+        // representation, that being 12 bytes.
+        //
+
+        if (v == 0)
+        {
+          b[0] = 1;
+          b[1] = 128;
+
+          return;
+        }
+
+        bool sig (false);
+        size_t n (0);
+        unsigned char t[11], *m (t);
+
+        if (v < 0)
+        {
+          // Termination marker for negative numbers.
+          //
+          *m++ = 102;
+
+          while (v != 0)
+          {
+            int r (static_cast<int> (v % 100));
+            sig = sig || r != 0;
+
+            if (sig)
+              *m++ = static_cast<unsigned char> (101 + r);
+
+            v /= 100;
+            ++n;
+          }
+
+          // The exponent is one less than the number of base 100 digits. It is
+          // inverted for negative values.
+          //
+          b[1] = static_cast<unsigned char> (~(n + 192));
+        }
+        else
+        {
+          while (v != 0)
+          {
+            int r (static_cast<int> (v % 100));
+            sig = sig || r != 0;
+
+            if (sig)
+              *m++ = static_cast<unsigned char> (r + 1);
+
+            v /= 100;
+            ++n;
+          }
+
+          // Exponent is one less than the number of base 100 digits.
+          //
+          b[1] = static_cast<unsigned char> (n + 192);
+        }
+
+        // Set the length.
+        //
+        b[0] = static_cast<unsigned char> (m - t + 1);
+
+        // Set the significant digits in big-endian byte order and the
+        // terminator, if any.
+        //
+        for (size_t i (2); m > t; ++i)
+          b[i] = *--m;
+      }
+
+      unsigned long long
+      number_to_uint64 (const unsigned char* b)
+      {
+        int n (b[0]);
+
+        // Zero is represented by zero significant bits and an exponent
+        // set to 128.
+        //
+        if (n == 1)
+        {
+          assert (b[1] == 128);
+          return 0;
+        }
+
+        unsigned long long v (0);
+
+        // Test the sign bit of the exponent.
+        //
+        if (b[1] & 0x80)
+        {
+          assert (false);
+          return 0;
+        }
+
+        // The unbiased exponent of a positive number may be calculated as
+        // b[1] - 128 - 65. For an integer, this is the order of magnitude
+        // of the number. Calculate the maximum weight, 100 ^ o, where o is
+        // the order of magnitude of the number.
+        //
+        unsigned long long w (1);
+
+        for (size_t i (0), o (b[1] - 193); i < o; ++i)
+          w *= 100;
+
+        // Accumlate the sum of the significant base-100 terms.
+        //
+        for (const unsigned char* m (b + 2), *e (b + 1 + n); m < e; ++m)
+        {
+          v += (*m - 1) * w;
+          w /= 100;
+        }
+
+        return v;
+      }
+
+      void
+      uint64_to_number (unsigned char* b, unsigned long long v)
+      {
+        // We assume that b is long enough to contain an unsigned long long
+        // VARNUM representation, that being 12 bytes.
+        //
+
+        if (v == 0)
+        {
+          b[0] = 1;
+          b[1] = 128;
+
+          return;
+        }
+
+        bool sig (false);
+        size_t n (0);
+        unsigned char t[11], *m (t);
+
+        while (v != 0)
+        {
+          int r (static_cast<int> (v % 100));
+          sig = sig || r != 0;
+
+          if (sig)
+            *m++ = static_cast<unsigned char> (r + 1);
+
+          v /= 100;
+          ++n;
+        }
+
+        // Exponent is one less than the number of base 100 digits.
+        //
+        b[1] = static_cast<unsigned char> (n + 192);
+
+        // Set the length.
+        //
+        b[0] = static_cast<unsigned char> (m - t + 1);
+
+        // Set the significant digits in big-endian byte order.
+        //
+        for (size_t i (2); m > t; ++i)
+          b[i] = *--m;
+      }
+    }
+  }
+}