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// file : odb/oracle/details/number.cxx
// copyright : Copyright (c) 2005-2019 Code Synthesis Tools CC
// license : ODB NCUEL; 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 NUMBER type's binary representation is made up of the following
// bit fields, ordered in increasing memory address.
//
// 000 to 007: 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.
//
// 008 to 167: The mantissa bits. Each byte of this field represents a
// single base-100 value.
//
//
long long
number_to_int64 (const char* b, size_t n)
{
// All bytes in the buffer are interpreted as unsigned.
//
const unsigned char* ub (reinterpret_cast<const unsigned char*> (b));
// Zero is represented by zero significant bits and an exponent
// set to 128.
//
if (n == 1)
{
assert (ub[0] == 128);
return 0;
}
long long v (0);
// Test the sign bit of the exponent.
//
if ((ub[0] & 0x80) != 0)
{
// The unbiased exponent of a positive number may be calculated as
// ub[0 - 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 (ub[0] - 193); i < o; ++i)
w *= 100;
// Accumlate the sum of the significant base-100 terms.
//
for (const unsigned char* m (ub + 1), *e (ub + n); m < e; ++m)
{
v += (*m - 1) * w;
w /= 100;
}
}
else
{
// The unbiased exponent of a negative number is calculated as
// (~ub[0] & 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 ((~ub[0] & 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 (ub + 1), *e (ub + n - 1); m < e; ++m)
{
v -= (101 - *m) * w;
w /= 100;
}
}
return v;
}
void
int64_to_number (char* b, size_t& n, long long v)
{
// We assume that b is long enough to contain a long long NUMBER
// representation, that being 12 bytes.
//
// All bytes in the buffer are interpreted as unsigned.
//
unsigned char* ub (reinterpret_cast<unsigned char*> (b));
if (v == 0)
{
ub[0] = 128;
n = 1;
return;
}
bool sig (false);
unsigned char t[11], *m (t);
n = 0;
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.
//
ub[0] = 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.
//
ub[0] = static_cast<unsigned char> (n + 192);
}
// Set the length.
//
n = 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 (1); m > t; ++i)
ub[i] = *--m;
}
unsigned long long
number_to_uint64 (const char* b, size_t n)
{
// All bytes in the buffer are interpreted as unsigned.
//
const unsigned char* ub (reinterpret_cast<const unsigned char*> (b));
// Zero is represented by zero significant bits and an exponent
// set to 128.
//
if (n == 1)
{
assert (ub[0] == 128);
return 0;
}
unsigned long long v (0);
// Test the sign bit of the exponent.
//
if ((ub[0] & 0x80) == 0)
{
assert (false);
return 0;
}
// The unbiased exponent of a positive number may be calculated as
// ub[0] - 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 (ub[0] - 193); i < o; ++i)
w *= 100;
// Accumlate the sum of the significant base-100 terms.
//
for (const unsigned char* m (ub + 1), *e (ub + n); m < e; ++m)
{
v += (*m - 1) * w;
w /= 100;
}
return v;
}
void
uint64_to_number (char* b, size_t& n, unsigned long long v)
{
// We assume that b is long enough to contain an unsigned long long
// NUMBER representation, that being 12 bytes.
//
// All bytes in the buffer are interpreted as unsigned.
//
unsigned char* ub (reinterpret_cast<unsigned char*> (b));
if (v == 0)
{
ub[0] = 128;
n = 1;
return;
}
bool sig (false);
unsigned char t[11], *m (t);
n = 0;
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.
//
ub[0] = static_cast<unsigned char> (n + 192);
// Set the length.
//
n = static_cast<unsigned char> (m - t + 1);
// Set the significant digits in big-endian byte order.
//
for (size_t i (1); m > t; ++i)
ub[i] = *--m;
}
}
}
}
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