X-Git-Url: https://git.donarmstrong.com/?p=rsem.git;a=blobdiff_plain;f=boost%2Frandom%2Fdetail%2Fconst_mod.hpp;h=9778f55179a91eac4d1e358542abc97b7f0546a1;hp=e0a8839031a2c400b58573f6ef97368f2dcce5bb;hb=2d71eb92104693ca9baa5a2e1c23eeca776d8fd3;hpb=da57529b92adbb7ae74a89861cb39fb35ac7c62d

diff --git a/boost/random/detail/const_mod.hpp b/boost/random/detail/const_mod.hpp
index e0a8839..9778f55 100644
--- a/boost/random/detail/const_mod.hpp
+++ b/boost/random/detail/const_mod.hpp
@@ -7,7 +7,7 @@
  *
  * See http://www.boost.org for most recent version including documentation.
  *
- * $Id: const_mod.hpp 58649 2010-01-02 21:23:17Z steven_watanabe $
+ * $Id: const_mod.hpp 71018 2011-04-05 21:27:52Z steven_watanabe $
  *
  * Revision history
  *  2001-02-18  moved to individual header files
@@ -16,113 +16,101 @@
 #ifndef BOOST_RANDOM_CONST_MOD_HPP
 #define BOOST_RANDOM_CONST_MOD_HPP
 
-#include <cassert>
+#include <boost/assert.hpp>
 #include <boost/static_assert.hpp>
-#include <boost/cstdint.hpp>
 #include <boost/integer_traits.hpp>
-#include <boost/detail/workaround.hpp>
+#include <boost/type_traits/make_unsigned.hpp>
+#include <boost/random/detail/large_arithmetic.hpp>
 
 #include <boost/random/detail/disable_warnings.hpp>
 
 namespace boost {
 namespace random {
 
-/*
- * Some random number generators require modular arithmetic.  Put
- * everything we need here.
- * IntType must be an integral type.
- */
-
-namespace detail {
-
-  template<bool is_signed>
-  struct do_add
-  { };
-
-  template<>
-  struct do_add<true>
-  {
-    template<class IntType>
-    static IntType add(IntType m, IntType x, IntType c)
-    {
-      if (x < m - c)
-        return x + c;
-      else
-        return x - (m-c);
-    }
-  };
-
-  template<>
-  struct do_add<false>
-  {
-    template<class IntType>
-    static IntType add(IntType, IntType, IntType)
-    {
-      // difficult
-      assert(!"const_mod::add with c too large");
-      return 0;
-    }
-  };
-} // namespace detail
-
-#if !(defined(__BORLANDC__) && (__BORLANDC__ == 0x560))
-
 template<class IntType, IntType m>
 class const_mod
 {
 public:
+  static IntType apply(IntType x)
+  {
+    if(((unsigned_m() - 1) & unsigned_m()) == 0)
+      return (unsigned_type(x)) & (unsigned_m() - 1);
+    else {
+      IntType supress_warnings = (m == 0);
+      BOOST_ASSERT(supress_warnings == 0);
+      return x % (m + supress_warnings);
+    }
+  }
+
   static IntType add(IntType x, IntType c)
   {
-    if(c == 0)
+    if(((unsigned_m() - 1) & unsigned_m()) == 0)
+      return (unsigned_type(x) + unsigned_type(c)) & (unsigned_m() - 1);
+    else if(c == 0)
       return x;
-    else if(c <= traits::const_max - m)    // i.e. m+c < max
-      return add_small(x, c);
+    else if(x < m - c)
+      return x + c;
     else
-      return detail::do_add<traits::is_signed>::add(m, x, c);
+      return x - (m - c);
   }
 
   static IntType mult(IntType a, IntType x)
   {
-    if(a == 1)
+    if(((unsigned_m() - 1) & unsigned_m()) == 0)
+      return unsigned_type(a) * unsigned_type(x) & (unsigned_m() - 1);
+    else if(a == 0)
+      return 0;
+    else if(a == 1)
       return x;
     else if(m <= traits::const_max/a)      // i.e. a*m <= max
       return mult_small(a, x);
     else if(traits::is_signed && (m%a < m/a))
       return mult_schrage(a, x);
-    else {
-      // difficult
-      assert(!"const_mod::mult with a too large");
-      return 0;
-    }
+    else
+      return mult_general(a, x);
   }
 
   static IntType mult_add(IntType a, IntType x, IntType c)
   {
-    if(m <= (traits::const_max-c)/a)   // i.e. a*m+c <= max
-      return (a*x+c) % m;
-    else
+    if(((unsigned_m() - 1) & unsigned_m()) == 0)
+      return (unsigned_type(a) * unsigned_type(x) + unsigned_type(c)) & (unsigned_m() - 1);
+    else if(a == 0)
+      return c;
+    else if(m <= (traits::const_max-c)/a) {  // i.e. a*m+c <= max
+      IntType supress_warnings = (m == 0);
+      BOOST_ASSERT(supress_warnings == 0);
+      return (a*x+c) % (m + supress_warnings);
+    } else
       return add(mult(a, x), c);
   }
 
+  static IntType pow(IntType a, boost::uintmax_t exponent)
+  {
+      IntType result = 1;
+      while(exponent != 0) {
+          if(exponent % 2 == 1) {
+              result = mult(result, a);
+          }
+          a = mult(a, a);
+          exponent /= 2;
+      }
+      return result;
+  }
+
   static IntType invert(IntType x)
-  { return x == 0 ? 0 : invert_euclidian(x); }
+  { return x == 0 ? 0 : (m == 0? invert_euclidian0(x) : invert_euclidian(x)); }
 
 private:
   typedef integer_traits<IntType> traits;
+  typedef typename make_unsigned<IntType>::type unsigned_type;
 
   const_mod();      // don't instantiate
 
-  static IntType add_small(IntType x, IntType c)
-  {
-    x += c;
-    if(x >= m)
-      x -= m;
-    return x;
-  }
-
   static IntType mult_small(IntType a, IntType x)
   {
-    return a*x % m;
+    IntType supress_warnings = (m == 0);
+    BOOST_ASSERT(supress_warnings == 0);
+    return a*x % (m + supress_warnings);
   }
 
   static IntType mult_schrage(IntType a, IntType value)
@@ -130,231 +118,96 @@ private:
     const IntType q = m / a;
     const IntType r = m % a;
 
-    assert(r < q);        // check that overflow cannot happen
+    BOOST_ASSERT(r < q);        // check that overflow cannot happen
 
-    value = a*(value%q) - r*(value/q);
-    // An optimizer bug in the SGI MIPSpro 7.3.1.x compiler requires this
-    // convoluted formulation of the loop (Synge Todo)
-    for(;;) {
-      if (value > 0)
-        break;
-      value += m;
+    return sub(a*(value%q), r*(value/q));
+  }
+
+  static IntType mult_general(IntType a, IntType b)
+  {
+    IntType suppress_warnings = (m == 0);
+    BOOST_ASSERT(suppress_warnings == 0);
+    IntType modulus = m + suppress_warnings;
+    BOOST_ASSERT(modulus == m);
+    if(::boost::uintmax_t(modulus) <=
+        (::std::numeric_limits< ::boost::uintmax_t>::max)() / modulus)
+    {
+      return static_cast<IntType>(boost::uintmax_t(a) * b % modulus);
+    } else {
+      return static_cast<IntType>(detail::mulmod(a, b, modulus));
     }
-    return value;
+  }
+
+  static IntType sub(IntType a, IntType b)
+  {
+    if(a < b)
+      return m - (b - a);
+    else
+      return a - b;
+  }
+
+  static unsigned_type unsigned_m()
+  {
+      if(m == 0) {
+          return unsigned_type((std::numeric_limits<IntType>::max)()) + 1;
+      } else {
+          return unsigned_type(m);
+      }
   }
 
   // invert c in the finite field (mod m) (m must be prime)
   static IntType invert_euclidian(IntType c)
   {
     // we are interested in the gcd factor for c, because this is our inverse
-    BOOST_STATIC_ASSERT(m > 0);
-#if BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
-    assert(boost::integer_traits<IntType>::is_signed);
-#elif !defined(BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS)
-    BOOST_STATIC_ASSERT(boost::integer_traits<IntType>::is_signed);
-#endif
-    assert(c > 0);
+    BOOST_ASSERT(c > 0);
     IntType l1 = 0;
     IntType l2 = 1;
     IntType n = c;
     IntType p = m;
     for(;;) {
       IntType q = p / n;
-      l1 -= q * l2;           // this requires a signed IntType!
+      l1 += q * l2;
       p -= q * n;
       if(p == 0)
-        return (l2 < 1 ? l2 + m : l2);
+        return l2;
       IntType q2 = n / p;
-      l2 -= q2 * l1;
+      l2 += q2 * l1;
       n -= q2 * p;
       if(n == 0)
-        return (l1 < 1 ? l1 + m : l1);
+        return m - l1;
     }
   }
-};
-
-// The modulus is exactly the word size: rely on machine overflow handling.
-// Due to a GCC bug, we cannot partially specialize in the presence of
-// template value parameters.
-template<>
-class const_mod<unsigned int, 0>
-{
-  typedef unsigned int IntType;
-public:
-  static IntType add(IntType x, IntType c) { return x+c; }
-  static IntType mult(IntType a, IntType x) { return a*x; }
-  static IntType mult_add(IntType a, IntType x, IntType c) { return a*x+c; }
-
-  // m is not prime, thus invert is not useful
-private:                      // don't instantiate
-  const_mod();
-};
-
-template<>
-class const_mod<unsigned long, 0>
-{
-  typedef unsigned long IntType;
-public:
-  static IntType add(IntType x, IntType c) { return x+c; }
-  static IntType mult(IntType a, IntType x) { return a*x; }
-  static IntType mult_add(IntType a, IntType x, IntType c) { return a*x+c; }
-
-  // m is not prime, thus invert is not useful
-private:                      // don't instantiate
-  const_mod();
-};
-
-// the modulus is some power of 2: rely partly on machine overflow handling
-// we only specialize for rand48 at the moment
-#ifndef BOOST_NO_INT64_T
-template<>
-class const_mod<uint64_t, uint64_t(1) << 48>
-{
-  typedef uint64_t IntType;
-public:
-  static IntType add(IntType x, IntType c) { return c == 0 ? x : mod(x+c); }
-  static IntType mult(IntType a, IntType x) { return mod(a*x); }
-  static IntType mult_add(IntType a, IntType x, IntType c)
-    { return mod(a*x+c); }
-  static IntType mod(IntType x) { return x &= ((uint64_t(1) << 48)-1); }
-
-  // m is not prime, thus invert is not useful
-private:                      // don't instantiate
-  const_mod();
-};
-#endif /* !BOOST_NO_INT64_T */
-
-#else
-
-//
-// for some reason Borland C++ Builder 6 has problems with
-// the full specialisations of const_mod, define a generic version
-// instead, the compiler will optimise away the const-if statements:
-//
 
-template<class IntType, IntType m>
-class const_mod
-{
-public:
-  static IntType add(IntType x, IntType c)
-  {
-    if(0 == m)
-    {
-       return x+c;
-    }
-    else
-    {
-       if(c == 0)
-         return x;
-       else if(c <= traits::const_max - m)    // i.e. m+c < max
-         return add_small(x, c);
-       else
-         return detail::do_add<traits::is_signed>::add(m, x, c);
-    }
-  }
-
-  static IntType mult(IntType a, IntType x)
-  {
-    if(x == 0)
-    {
-       return a*x;
-    }
-    else
-    {
-       if(a == 1)
-         return x;
-       else if(m <= traits::const_max/a)      // i.e. a*m <= max
-         return mult_small(a, x);
-       else if(traits::is_signed && (m%a < m/a))
-         return mult_schrage(a, x);
-       else {
-         // difficult
-         assert(!"const_mod::mult with a too large");
-         return 0;
-       }
-    }
-  }
-
-  static IntType mult_add(IntType a, IntType x, IntType c)
-  {
-    if(m == 0)
-    {
-       return a*x+c;
-    }
-    else
-    {
-       if(m <= (traits::const_max-c)/a)   // i.e. a*m+c <= max
-         return (a*x+c) % m;
-       else
-         return add(mult(a, x), c);
-    }
-  }
-
-  static IntType invert(IntType x)
-  { return x == 0 ? 0 : invert_euclidian(x); }
-
-private:
-  typedef integer_traits<IntType> traits;
-
-  const_mod();      // don't instantiate
-
-  static IntType add_small(IntType x, IntType c)
-  {
-    x += c;
-    if(x >= m)
-      x -= m;
-    return x;
-  }
-
-  static IntType mult_small(IntType a, IntType x)
-  {
-    return a*x % m;
-  }
-
-  static IntType mult_schrage(IntType a, IntType value)
-  {
-    const IntType q = m / a;
-    const IntType r = m % a;
-
-    assert(r < q);        // check that overflow cannot happen
-
-    value = a*(value%q) - r*(value/q);
-    while(value <= 0)
-      value += m;
-    return value;
-  }
-
-  // invert c in the finite field (mod m) (m must be prime)
-  static IntType invert_euclidian(IntType c)
+  // invert c in the finite field (mod m) (c must be relatively prime to m)
+  static IntType invert_euclidian0(IntType c)
   {
     // we are interested in the gcd factor for c, because this is our inverse
-    BOOST_STATIC_ASSERT(m > 0);
-#ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS
-    BOOST_STATIC_ASSERT(boost::integer_traits<IntType>::is_signed);
-#endif
-    assert(c > 0);
+    BOOST_ASSERT(c > 0);
+    if(c == 1) return 1;
     IntType l1 = 0;
     IntType l2 = 1;
     IntType n = c;
     IntType p = m;
+    IntType max = (std::numeric_limits<IntType>::max)();
+    IntType q = max / n;
+    BOOST_ASSERT(max % n != n - 1 && "c must be relatively prime to m.");
+    l1 += q * l2;
+    p = max - q * n + 1;
     for(;;) {
-      IntType q = p / n;
-      l1 -= q * l2;           // this requires a signed IntType!
-      p -= q * n;
       if(p == 0)
-        return (l2 < 1 ? l2 + m : l2);
+        return l2;
       IntType q2 = n / p;
-      l2 -= q2 * l1;
+      l2 += q2 * l1;
       n -= q2 * p;
       if(n == 0)
-        return (l1 < 1 ? l1 + m : l1);
+        return m - l1;
+      q = p / n;
+      l1 += q * l2;
+      p -= q * n;
     }
   }
 };
 
-
-#endif
-
 } // namespace random
 } // namespace boost