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#include "slang-random-generator.h"
namespace Slang
{
/* !!!!!!!!!!!!!!!!!!!!!!!!!!!! RandomGenerator !!!!!!!!!!!!!!!!!!!!!!!! */
float RandomGenerator::nextUnitFloat32()
{
int32_t intValue = nextInt32();
return (intValue & 0x7fffffff) * (1.0f / float(0x7fffffff));
}
bool RandomGenerator::nextBool()
{
uint32_t bits = uint32_t(nextInt32());
// Xor together all bits in each byte
bits = ((bits & 0xaaaaaaaa) >> 1) ^ (bits & 0x55555555);
bits = ((bits & 0x44444444) >> 2) ^ (bits & 0x11111111);
bits = ((bits & 0x10101010) >> 4) ^ (bits & 0x01010101);
// In effect is the xor of all the bits of the original last byte
return (bits & 1) != 0;
}
int64_t RandomGenerator::nextInt64()
{
const int32_t high = nextInt32();
const int32_t low = nextInt32();
return (int64_t(high) << 32) | low;
}
uint32_t RandomGenerator::nextUInt32InRange(uint32_t min, uint32_t max)
{
// Make sure max is at least in
max = (max >= min) ? max : min;
// Make 64 bit so can be lazier than having to take care of 32 bit overflow/underflow issues
uint32_t diff = max - min;
if (diff <= 1)
{
return min;
}
return (nextUInt32() % diff) + min;
}
int32_t RandomGenerator::nextInt32InRange(int32_t min, int32_t max)
{
// Make sure max is at least in
max = (max >= min) ? max : min;
// Make 64 bit so can be lazier than having to take care of 32 bit overflow/underflow issues
uint32_t diff = uint32_t(int64_t(max) - int64_t(min));
if (diff <= 1)
{
return min;
}
return int32_t(int64_t(nextUInt32() % diff) + min);
}
int64_t RandomGenerator::nextInt64InRange(int64_t min, int64_t max)
{
int64_t diff = max - min;
if (diff <= 1)
{
return min;
}
return (nextPositiveInt64() % diff) + min;
}
static uint8_t* _nextData(RandomGenerator* rand, uint8_t* out, size_t size)
{
if (size)
{
SLANG_ASSERT(size <= 4);
uint32_t v = uint32_t(rand->nextInt32());
uint8_t* dst = (uint8_t*)out;
for (size_t i = 0; i < size; ++i)
{
dst[i] = uint8_t(v);
v >>= 8;
}
}
return out + size;
}
void RandomGenerator::nextData(void* out, size_t size)
{
uint8_t* dst = (uint8_t*)out;
uint8_t* const end = dst + size;
// For short runs just output
if (size <= 4)
{
_nextData(this, dst, size);
return;
}
{
const size_t preAlign = size_t(((size_t(dst) + 3) & ~size_t(3)) - size_t(dst));
dst = _nextData(this, dst, preAlign);
}
// Check invariants
SLANG_ASSERT((size_t(dst) & 3) == 0 && end >= dst);
{
const size_t middleCount = size_t(end - dst) >> 2;
if (middleCount)
{
nextInt32s((int32_t*)dst, middleCount);
dst += middleCount * sizeof(int32_t);
}
}
// Check invariants
SLANG_ASSERT((size_t(dst) & 3) == 0 && end >= dst);
_nextData(this, dst, size_t(end - dst));
}
/* static */ RandomGenerator* RandomGenerator::create(int32_t seed)
{
return new DefaultRandomGenerator(seed);
}
/* !!!!!!!!!!!!!!!!!!!!!!!!!!!! Mt19937RandomGenerator !!!!!!!!!!!!!!!!!!!!!!!! */
Mt19937RandomGenerator::Mt19937RandomGenerator()
{
reset(21452);
}
Mt19937RandomGenerator::Mt19937RandomGenerator(const ThisType& rhs)
{
*this = rhs;
}
Mt19937RandomGenerator::Mt19937RandomGenerator(int32_t seed)
{
reset(seed);
}
void Mt19937RandomGenerator::_generate()
{
const uint32_t xorValue = 2567483615u;
for (int i = 0; i < kNumEntries - 1; ++i)
{
const uint32_t y = (m_mt[i] & 0x80000000) + (m_mt[i + 1] & 0x7fffffff);
// o = (i + 397) % kNumEntries
int32_t o = i + 397;
o = (o >= kNumEntries) ? (o - kNumEntries) : o;
m_mt[i] = m_mt[o] ^ (y >> 1);
// If y is odd
if (y & 1)
{
m_mt[i] = m_mt[i] ^ xorValue;
}
}
// Last
{
const int i = kNumEntries - 1;
const uint32_t y = (m_mt[i] & 0x80000000) + (m_mt[0] & 0x7fffffff);
const int32_t o = ((i + 397) - kNumEntries);
m_mt[i] = m_mt[o] ^ (y >> 1);
// If y is odd
if (y & 1)
{
m_mt[i] = m_mt[i] ^ xorValue;
}
}
m_index = 0;
}
void Mt19937RandomGenerator::reset(int32_t seedIn)
{
m_index = 0;
m_mt[0] = uint32_t(seedIn);
for (int i = 1; i < kNumEntries; ++i)
{
m_mt[i] = (1812433253 * (m_mt[i - 1] ^ (m_mt[i - 1] >> 30)) + i);
}
}
int32_t Mt19937RandomGenerator::nextInt32()
{
if (m_index >= kNumEntries)
{
_generate();
}
uint32_t y = m_mt[m_index++];
y = y ^ (y >> 11);
y = y ^ ((y << 7) & uint32_t(0x9d2c5680u));
y = y ^ ((y << 15) & uint32_t(0xefc6000u));
y = y ^ (y >> 18);
return int32_t(y);
}
void Mt19937RandomGenerator::nextInt32s(int32_t* dst, size_t count)
{
while (count)
{
if (m_index >= kNumEntries)
{
_generate();
}
const size_t remaining = kNumEntries - m_index;
const size_t run = (count < remaining) ? count : remaining;
const uint32_t* src = m_mt + m_index;
for (size_t i = 0; i < run; i++)
{
uint32_t y = src[i];
y = y ^ (y >> 11);
y = y ^ ((y << 7) & uint32_t(0x9d2c5680u));
y = y ^ ((y << 15) & uint32_t(0xefc6000u));
y = y ^ (y >> 18);
dst[i] = int32_t(y);
}
m_index += int(run);
dst += run;
count -= run;
}
}
} // namespace Slang
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