shift to the Total-Random fork of the PCG PRNG

Author: bhaller

VERSIONS

@@ -36,6 +36,7 @@ development head (in the master branch):
 	CI workflow for calculating code coverage with Codecov, thanks to Andy Kern, https://github.com/MesserLab/SLiM/pull/601
 	fix #594, the pedigreeID and haplosomePedigreeID properties should be accessible (without other predigree-tracking features) in tree-seq models, even without pedigree tracking being enabled
 	fix #584, a way to generate a random 64-bit integer is needed; added new rdunif64(integer$ n) function for this purpose
+	shift over to Release 1 of the Total-Random fork of the PCG random number generator (better maintained), found at https://github.com/Total-Random/pcg-cpp/releases/tag/v1.0
 
 
 version 5.1 (Eidos version 4.1):

eidos/pcg_extras.hpp

@@ -55,6 +55,9 @@
 
 #ifdef __GNUC__
     #define PCG_NOINLINE __attribute__((noinline))
+#elif defined(_MSC_VER)
+    #define PCG_NOINLINE __declspec(noinline)
+    #pragma warning(disable:4127) // conditional expression is constant
 #else
     #define PCG_NOINLINE
 #endif
@@ -263,21 +266,11 @@ inline std::istream& operator>>(std::istream& in, uint8_t& value)
 template <typename itype>
 inline itype unxorshift(itype x, bitcount_t bits, bitcount_t shift)
 {
-    if (2*shift >= bits) {
-        return x ^ (x >> shift);
-    }
-    itype lowmask1 = (itype(1U) << (bits - shift*2)) - 1;
-    itype highmask1 = ~lowmask1;
-    itype top1 = x;
-    itype bottom1 = x & lowmask1;
-    top1 ^= top1 >> shift;
-    top1 &= highmask1;
-    x = top1 | bottom1;
-    itype lowmask2 = (itype(1U) << (bits - shift)) - 1;
-    itype bottom2 = x & lowmask2;
-    bottom2 = unxorshift(bottom2, bits - shift, shift);
-    bottom2 &= lowmask1;
-    return top1 | bottom2;
+    do {
+        x ^= x >> shift;
+        shift *= 2u;
+    } while(shift < bits);
+    return x;
 }
 
 /*
@@ -411,10 +404,10 @@ SrcIter uneven_copy_impl(
     typedef typename std::iterator_traits<SrcIter>::value_type  src_t;
     typedef typename std::iterator_traits<DestIter>::value_type dest_t;
 
-    constexpr bitcount_t SRC_SIZE  = sizeof(src_t);
-    constexpr bitcount_t DEST_SIZE = sizeof(dest_t);
-    constexpr bitcount_t DEST_BITS = DEST_SIZE * 8;
-    constexpr bitcount_t SCALE     = SRC_SIZE / DEST_SIZE;
+    constexpr size_t SRC_SIZE  = sizeof(src_t);
+    constexpr size_t DEST_SIZE = sizeof(dest_t);
+    constexpr bitcount_t DEST_BITS = bitcount_t(DEST_SIZE * 8);
+    constexpr size_t SCALE     = SRC_SIZE / DEST_SIZE;
 
     size_t count = 0;
     src_t value = 0;
@@ -447,10 +440,10 @@ SrcIter uneven_copy_impl(
 
     while (dest_first != dest_last) {
         dest_t value(0UL);
-        unsigned int shift = 0;
+        size_t shift = 0;
 
         for (size_t i = 0; i < SCALE; ++i) {
-            value |= dest_t(*src_first++) << shift;
+            value |= dest_t(*src_first++) << bitcount_t(shift);
             shift += SRC_BITS;
         }
 
@@ -583,9 +576,9 @@ class seed_seq_from {
 private:
     RngType rng_;
 
+public:
     typedef uint_least32_t result_type;
 
-public:
     template<typename... Args>
     seed_seq_from(Args&&... args) :
         rng_(std::forward<Args>(args)...)
@@ -628,6 +621,9 @@ struct static_arbitrary_seed {
 public:
     static constexpr IntType value = fnv(IntType(2166136261U ^ sizeof(IntType)),
                         __DATE__ __TIME__ __FILE__);
+
+    //Prevent creation, while keeping GCC from giving a warning
+    static_arbitrary_seed() = delete;
 };
 
 // Sometimes, when debugging or testing, it's handy to be able print the name

eidos/pcg_random.hpp

@@ -90,14 +90,23 @@
 
 #ifdef _MSC_VER
     #pragma warning(disable:4146)
+    #pragma warning(disable:4127) // conditional expression is constant
 #endif
 
 #ifdef _MSC_VER
     #define PCG_ALWAYS_INLINE __forceinline
+    #if defined(_MSC_FULL_VER) && _MSC_FULL_VER >= 190024210
+        // available since VS 2015 Update 2/3
+        #define PCG_EBO __declspec(empty_bases)
+    #else
+        #define PCG_EBO
+    #endif
 #elif __GNUC__
     #define PCG_ALWAYS_INLINE __attribute__((always_inline))
+    #define PCG_EBO
 #else
     #define PCG_ALWAYS_INLINE inline
+    #define PCG_EBO
 #endif
 
 /*
@@ -333,7 +342,7 @@ class specific_stream {
 
     void set_stream(itype specific_seq)
     {
-         inc_ = (specific_seq << 1) | 1;
+         inc_ = (specific_seq << 1) | itype(1U);
     }
 
     static constexpr bool can_specify_stream = true;
@@ -375,7 +384,7 @@ template <typename xtype, typename itype,
           bool output_previous = true,
           typename stream_mixin = oneseq_stream<itype>,
           typename multiplier_mixin = default_multiplier<itype> >
-class engine : protected output_mixin,
+class PCG_EBO engine : protected output_mixin,
                public stream_mixin,
                protected multiplier_mixin {
 protected:
@@ -618,7 +627,7 @@ operator>>(std::basic_istream<CharT,Traits>& in,
 
     if (!in.fail()) {
         bool good = true;
-        if (multiplier != rng.multiplier()) {
+        if (multiplier != itype(rng.multiplier())) {
            good = false;
         } else if (rng.can_specify_stream) {
            rng.set_stream(increment >> 1);
@@ -676,8 +685,8 @@ itype engine<xtype,itype,output_mixin,output_previous,stream_mixin,
     itype cur_state, itype newstate, itype cur_mult, itype cur_plus, itype mask)
 {
     constexpr itype ONE  = 1u;  // itype could be weird, so use constant
-    bool is_mcg = cur_plus == itype(0);
-    itype the_bit = is_mcg ? itype(4u) : itype(1u);
+    bool is_mcg_internal = cur_plus == itype(0);
+    itype the_bit = is_mcg_internal ? itype(4u) : itype(1u);
     itype distance = 0u;
     while ((cur_state & mask) != (newstate & mask)) {
        if ((cur_state & the_bit) != (newstate & the_bit)) {
@@ -689,7 +698,7 @@ itype engine<xtype,itype,output_mixin,output_previous,stream_mixin,
        cur_plus = (cur_mult+ONE)*cur_plus;
        cur_mult *= cur_mult;
     }
-    return is_mcg ? distance >> 2 : distance;
+    return is_mcg_internal ? distance >> 2 : distance;
 }
 
 template <typename xtype, typename itype,
@@ -1187,7 +1196,7 @@ struct xsl_mixin {
 
 
 template <typename baseclass>
-struct inside_out : private baseclass {
+struct PCG_EBO inside_out : private baseclass {
     inside_out() = delete;
 
     typedef typename baseclass::result_type result_type;
@@ -1229,7 +1238,7 @@ struct inside_out : private baseclass {
 
 
 template <bitcount_t table_pow2, bitcount_t advance_pow2, typename baseclass, typename extvalclass, bool kdd = true>
-class extended : public baseclass {
+class PCG_EBO extended : public baseclass {
 public:
     typedef typename baseclass::state_type  state_type;
     typedef typename baseclass::result_type result_type;