Skip to content

Commit

Permalink
random: simplified prng
Browse files Browse the repository at this point in the history 
misc: various small changes
  • Loading branch information
@jeefo
jeefo committed Apr 25, 2024
1 parent 3596ac4 commit ea7a91b
Show file tree
Hide file tree
Showing 4 changed files with 65 additions and 70 deletions.
6 changes: 3 additions & 3 deletions crlib/array.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -275,7 +275,7 @@ template <typename T, ReservePolicy R = ReservePolicy::Multiple, size_t S = 0> c
int32_t shuffleLength = length <int32_t> ();

for (int32_t i = shuffleLength; i >= 1; --i) {
cr::swap (contents_[i - 1], contents_[rg.get (i, shuffleLength - 2)]);
cr::swap (contents_[i - 1], contents_[rg (i, shuffleLength - 2)]);
}
}

Expand Down Expand Up @@ -351,14 +351,14 @@ template <typename T, ReservePolicy R = ReservePolicy::Multiple, size_t S = 0> c
if (length_ <= 1) {
return contents_[0];
}
return contents_[rg.get (0, length <int32_t> () - 1)];
return contents_[rg (0, length <int32_t> () - 1)];
}

T &random () {
if (length_ <= 1) {
return contents_[0];
}
return contents_[rg.get (0, length <int32_t> () - 1)];
return contents_[rg (0, length <int32_t> () - 1)];
}

T *data () {
Expand Down
4 changes: 2 additions & 2 deletions crlib/http.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -318,7 +318,7 @@ class HttpClient final : public Singleton <HttpClient> {
String respCode = response.substr (responseCodeStart + cr::bufsize ("HTTP 1/1 "), 3);
respCode.trim ();

return static_cast <HttpClientResult> (respCode.int_ ());
return static_cast <HttpClientResult> (respCode.as <int> ());
}
return HttpClientResult::NotFound;
}
Expand Down Expand Up @@ -438,7 +438,7 @@ class HttpClient final : public Singleton <HttpClient> {
if (boundarySlash != String::InvalidIndex) {
boundaryName = localPath.substr (boundarySlash + 1);
}
StringRef boundaryLine = strings.format ("---crlib_upload_boundary_%d%d%d%d", rg.get (0, 9), rg.get (0, 9), rg.get (0, 9), rg.get (0, 9));
StringRef boundaryLine = strings.format ("---crlib_upload_boundary_%d%d%d%d", rg (0, 9), rg (0, 9), rg (0, 9), rg (0, 9));

String request, start, end;
start.appendf ("--%s\r\n", boundaryLine);
Expand Down
99 changes: 46 additions & 53 deletions crlib/random.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -12,81 +12,74 @@

CR_NAMESPACE_BEGIN

// random number generator, credits goes to https://prng.di.unimi.it/xoshiro128starstar.c
class Xoshiro128 final : public Singleton <Xoshiro128> {
namespace detail {
class SplitMix32 final {
private:
uint32_t state_ {};

public:
explicit SplitMix32 (const uint32_t state) noexcept : state_ (state) {}

public:
[[nodiscard]] decltype (auto) next () noexcept {
auto z = (state_ += 0x9e3779b9);
z = (z ^ (z >> 16)) * 0x85ebca6b;
z = (z ^ (z >> 13)) * 0xc2b2ae35;
return z ^ (z >> 16);
}
};
}

// random number generator (xoshiro based)
class RWrand final : public Singleton <RWrand> {
private:
uint32_t states_[4] {};
uint32_t states2_[4] {};
static constexpr uint64_t limit_ { static_cast <uint64_t> (1) << 32ull };
static constexpr uint64_t kRandMax { static_cast <uint64_t> (1) << 32ull };

private:
constexpr uint32_t rotl32 (const uint32_t x, int32_t k) {
return (x << k) | (x >> (32 - k));
}
uint32_t states_[3] {};

constexpr uint32_t splitmix32 (uint32_t &x) {
uint32_t z = (x += 0x9e3779b9);
z = (z ^ (z >> 16)) * 0x85ebca6b;
z = (z ^ (z >> 13)) * 0xc2b2ae35;
return z ^ (z >> 16);
}
public:
explicit RWrand () noexcept {
const auto seed = static_cast <uint32_t> (time (nullptr));

constexpr void seeder (uint32_t *state) {
uint32_t seed = 0;
detail::SplitMix32 smix (seed);

state[0] = splitmix32 (seed);
state[1] = splitmix32 (seed);
state[2] = splitmix32 (seed);
state[3] = splitmix32 (seed);
for (auto &state : states_) {
state = smix.next ();
}
}
~RWrand () = default;


private:
constexpr uint32_t scramble (uint32_t *states, const uint32_t result) {
const uint32_t t = states[1] << 9;
[[nodiscard]] decltype (auto) rotl (const uint32_t x, const int32_t k) noexcept {
return (x << k) | (x >> (32 - k));
}

states[2] ^= states[0];
states[3] ^= states[1];
states[1] ^= states[2];
states[0] ^= states[3];
states[2] ^= t;
states[3] = rotl32 (states[3], 11);
[[nodiscard]] decltype (auto) next () noexcept {
states_[0] = rotl (states_[0] + states_[1] + states_[2], 16);
states_[1] = states_[0];
states_[2] = states_[1];

return result;
return states_[0];
}

template <typename U> constexpr uint32_t next () {
public:
template <typename U> [[nodiscard]] decltype (auto) operator () (const U low, const U high) noexcept {
if constexpr (cr::is_same <U, int32_t>::value) {
return scramble (states_, rotl32 (states_[0] + states_[3], 7) + states_[0]);
return static_cast <int32_t> (next () * (static_cast <double> (high) - static_cast <double> (low) + 1.0) / kRandMax + static_cast <double> (low));
}
else if constexpr (cr::is_same <U, float>::value) {
return scramble (states2_, states2_[0] + states2_[3]);
return static_cast <float> (next () * (static_cast <double> (high) - static_cast <double> (low)) / (kRandMax - 1) + static_cast <double> (low));
}
}

public:
constexpr explicit Xoshiro128 () {
seeder (states_);
seeder (states2_);
}

public:
template <typename U, typename Void = void> constexpr U get (U, U) = delete;

template <typename Void = void> constexpr int32_t get (int32_t low, int32_t high) {
return static_cast <int32_t> (next <int32_t> () * (static_cast <double> (high) - static_cast <double> (low) + 1.0) / limit_ + static_cast <double> (low));
}

template <typename Void = void> constexpr float get (float low, float high) {
return static_cast <float> (next <float> () * (static_cast <double> (high) - static_cast <double> (low)) / (limit_ - 1) + static_cast <double> (low));
}

public:
constexpr bool chance (int32_t limit) {
return get <int32_t> (0, 100) < limit;
template <int32_t Low = 0, int32_t High = 100> [[nodiscard]] decltype (auto) chance (const int32_t limit) noexcept {
return operator () <int32_t> (Low, High) <= limit;
}
};

// expose global random generator
CR_EXPOSE_GLOBAL_SINGLETON (Xoshiro128, rg);
CR_EXPOSE_GLOBAL_SINGLETON (RWrand, rg);

CR_NAMESPACE_END
26 changes: 14 additions & 12 deletions crlib/string.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -137,12 +137,13 @@ class StringRef {
}

public:
int32_t int_ () const {
return atoi (chars ());
}

float float_ () const {
return static_cast <float> (atof (chars ()));
template <typename U> constexpr U as () const {
if constexpr (cr::is_same <U, float>::value) {
return static_cast <float> (atof (chars ()));
}
else if constexpr (cr::is_same <U, int>::value) {
return atoi (chars ());
}
}

bool startsWith (StringRef prefix) const {
Expand Down Expand Up @@ -692,12 +693,13 @@ class String final {
}

public:
int32_t int_ () const {
return str ().int_ ();
}

float float_ () const {
return str ().float_ ();
template <typename U> constexpr U as () const {
if constexpr (cr::is_same <U, float>::value) {
return str ().as <float> ();
}
else if constexpr (cr::is_same <U, int>::value) {
return str ().as <int> ();
}
}

// for range-based loops
Expand Down

0 comments on commit ea7a91b

Please sign in to comment.