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use-partytrick: allow accepting rng state as CLI arguments #52

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use-partytrick: allow accepting rng state as CLI arguments #52

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27 changes: 17 additions & 10 deletions sample/use-partytrick.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -20,8 +20,11 @@
*/

/*
* This program behaves like the spew program, the only difference is that
* after 1 MB of output, the output gets "interesting" for a brief while.
* This program behaves like the spew program, but can accept a different state
* as input as CLI arguments. With just the right state, the output can get
* "interesting" for a brief while. For example, the default_state makes the
* output generate an interesting string just after 1MB of output.
*
* See make-partytrick.cpp for more details.
*
* Typical usage:
Expand All @@ -40,7 +43,8 @@

#include "pcg_random.hpp"

static const char* saved_state =
/* Default state to use if no state is given as arguments. */
static const char* default_state =
"6364136223846793005 3503324247726078831 6557656048857751321 103238831 "
"665891259 1902651333 4073047566 368781010 3371458373 3520911659 1176018374 "
"1290944887 2479283234 2214499777 3287447736 4241043352 2808175048 83300271 "
Expand All @@ -52,11 +56,17 @@ static const char* saved_state =
"1413186342 1718872307 2898301505 1732438719 622306094 366401535 2963949396 "
"2676833081 98878999 999895120 425860638 4096143638 4063627507 2566817785";


int main()
int main(int argc, char *argv[])
{
pcg32_k64 rng;
std::istringstream inbuf(saved_state);

std::string args;
for (int i = 1; i < argc; i++) {
args += argv[i];
args += " ";
}

std::istringstream inbuf(argc == 68 ? args.c_str() : default_state);
inbuf >> rng;
std::clog << inbuf.str() << "\n\n";
if (inbuf.fail())
Expand All @@ -65,7 +75,7 @@ int main()
constexpr size_t BUFFER_SIZE = 1024ull * 128ull;
uint32_t buffer[BUFFER_SIZE];
constexpr size_t ROUNDS = 215 * 1073741824ull / sizeof(buffer);

for (size_t i = 0; i < ROUNDS; ++i) {
for (auto& v : buffer)
v = rng();
Expand All @@ -74,6 +84,3 @@ int main()

return 0;
}