luke/verilator
1
0
Fork 0
mirror of https://github.com/verilator/verilator.git synced 2026-09-02 18:58:51 +02:00
Code Issues Packages Projects Releases Wiki Activity

Support class srandom and class random stability.

Browse Source
This commit is contained in:
Wilson Snyder
2023-04-01 10:50:27 -04:00
parent 28eadded87
commit 69121633cf
21 changed files with 361 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files
include/verilated.cpp
+60 -12
View File
@@ -279,6 +279,52 @@ void VL_PRINTF_MT(const char* formatp, ...) VL_MT_SAFE {
//===========================================================================
// Random -- Mostly called at init time, so not inline.
VlRNG::VlRNG() VL_MT_SAFE {
// Starting point for this new class comes from the global RNG
VlRNG& fromr = vl_thread_rng();
m_state = fromr.m_state;
// Advance the *source* so it can later generate a new number
// Xoroshiro128+ algorithm
fromr.m_state[1] ^= fromr.m_state[0];
fromr.m_state[0] = (((fromr.m_state[0] << 55) | (fromr.m_state[0] >> 9)) ^ fromr.m_state[1]
^ (fromr.m_state[1] << 14));
fromr.m_state[1] = (fromr.m_state[1] << 36) | (fromr.m_state[1] >> 28);
}
uint64_t VlRNG::rand64() VL_MT_UNSAFE {
// Xoroshiro128+ algorithm
const uint64_t result = m_state[0] + m_state[1];
m_state[1] ^= m_state[0];
m_state[0] = (((m_state[0] << 55) | (m_state[0] >> 9)) ^ m_state[1] ^ (m_state[1] << 14));
m_state[1] = (m_state[1] << 36) | (m_state[1] >> 28);
return result;
}
uint64_t VlRNG::vl_thread_rng_rand64() VL_MT_SAFE {
VlRNG& fromr = vl_thread_rng();
const uint64_t result = fromr.m_state[0] + fromr.m_state[1];
fromr.m_state[1] ^= fromr.m_state[0];
fromr.m_state[0] = (((fromr.m_state[0] << 55) | (fromr.m_state[0] >> 9)) ^ fromr.m_state[1]
^ (fromr.m_state[1] << 14));
fromr.m_state[1] = (fromr.m_state[1] << 36) | (fromr.m_state[1] >> 28);
return result;
}
void VlRNG::srandom(uint64_t n) VL_MT_UNSAFE {
m_state[0] = n;
m_state[1] = m_state[0];
// Fix state as algorithm is slow to randomize if many zeros
// This causes a loss of ~ 1 bit of seed entropy, no big deal
if (VL_COUNTONES_I(m_state[0]) < 10) m_state[0] = ~m_state[0];
if (VL_COUNTONES_I(m_state[1]) < 10) m_state[1] = ~m_state[1];
}
// Unused: void VlRNG::set_randstate(const std::string& state) VL_MT_UNSAFE {
// Unused: if (VL_LIKELY(state.length() == sizeof(m_state))) {
// Unused: memcpy(m_state, state.data(), sizeof(m_state));
// Unused: }
// Unused: }
// Unused: std::string VlRNG::get_randstate() const VL_MT_UNSAFE {
// Unused: std::string out{reinterpret_cast<const char *>(&m_state), sizeof(m_state)};
// Unused: return out;
// Unused: }
static uint32_t vl_sys_rand32() VL_MT_SAFE {
// Return random 32-bits using system library.
// Used only to construct seed for Verilator's PRNG.
@@ -292,27 +338,23 @@ static uint32_t vl_sys_rand32() VL_MT_SAFE {
#endif
}
uint64_t vl_rand64() VL_MT_SAFE {
static thread_local uint64_t t_state[2];
VlRNG& VlRNG::vl_thread_rng() VL_MT_SAFE {
static thread_local VlRNG t_rng{0};
static thread_local uint32_t t_seedEpoch = 0;
// For speed, we use a thread-local epoch number to know when to reseed
// A thread always belongs to a single context, so this works out ok
if (VL_UNLIKELY(t_seedEpoch != VerilatedContextImp::randSeedEpoch())) {
// Set epoch before state, to avoid race case with new seeding
t_seedEpoch = VerilatedContextImp::randSeedEpoch();
t_state[0] = Verilated::threadContextp()->impp()->randSeedDefault64();
t_state[1] = t_state[0];
// Same as srandom() but here as needs to be VL_MT_SAFE
t_rng.m_state[0] = Verilated::threadContextp()->impp()->randSeedDefault64();
t_rng.m_state[1] = t_rng.m_state[0];
// Fix state as algorithm is slow to randomize if many zeros
// This causes a loss of ~ 1 bit of seed entropy, no big deal
if (VL_COUNTONES_I(t_state[0]) < 10) t_state[0] = ~t_state[0];
if (VL_COUNTONES_I(t_state[1]) < 10) t_state[1] = ~t_state[1];
if (VL_COUNTONES_I(t_rng.m_state[0]) < 10) t_rng.m_state[0] = ~t_rng.m_state[0];
if (VL_COUNTONES_I(t_rng.m_state[1]) < 10) t_rng.m_state[1] = ~t_rng.m_state[1];
}
// Xoroshiro128+ algorithm
const uint64_t result = t_state[0] + t_state[1];
t_state[1] ^= t_state[0];
t_state[0] = (((t_state[0] << 55) | (t_state[0] >> 9)) ^ t_state[1] ^ (t_state[1] << 14));
t_state[1] = (t_state[1] << 36) | (t_state[1] >> 28);
return result;
return t_rng;
}
WDataOutP VL_RANDOM_W(int obits, WDataOutP outwp) VL_MT_SAFE {
@@ -321,6 +363,12 @@ WDataOutP VL_RANDOM_W(int obits, WDataOutP outwp) VL_MT_SAFE {
return outwp;
}
WDataOutP VL_RANDOM_RNG_W(VlRNG& rngr, int obits, WDataOutP outwp) VL_MT_UNSAFE {
for (int i = 0; i < VL_WORDS_I(obits); ++i) outwp[i] = rngr.rand64();
// Last word is unclean
return outwp;
}
IData VL_RANDOM_SEEDED_II(IData& seedr) VL_MT_SAFE {
// $random - seed is a new seed to apply, then we return new seed
Verilated::threadContextp()->randSeed(static_cast<int>(seedr));