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authorwhitequark <whitequark@whitequark.org>2020-06-26 10:44:40 +0000
committerwhitequark <whitequark@whitequark.org>2020-06-26 11:30:00 +0000
commitf8b8ea0f3cdc4a2cf61a28c1ce44616555b62e4e (patch)
tree57bc2df0f567f054e77f8c38031254119f0989f1
parent3205180fd93d6abd1e63f5d8b794881896f57493 (diff)
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icebram: refactor seeding logic.
-rw-r--r--icebram/icebram.cc22
1 files changed, 14 insertions, 8 deletions
diff --git a/icebram/icebram.cc b/icebram/icebram.cc
index f585fcf..1bb3095 100644
--- a/icebram/icebram.cc
+++ b/icebram/icebram.cc
@@ -131,7 +131,7 @@ int main(int argc, char **argv)
bool verbose = false;
bool generate = false;
bool seed = false;
- uint32_t seed_nr = getpid();
+ uint32_t seed_opt = 0;
int opt;
while ((opt = getopt(argc, argv, "vgs:")) != -1)
@@ -146,7 +146,7 @@ int main(int argc, char **argv)
break;
case 's':
seed = true;
- seed_nr = atoi(optarg);
+ seed_opt = atoi(optarg);
break;
default:
help(argv[0]);
@@ -172,7 +172,17 @@ int main(int argc, char **argv)
}
if (verbose && seed)
- fprintf(stderr, "Seed: %d\n", seed_nr);
+ fprintf(stderr, "Seed: %d\n", seed_opt);
+
+ // If -s is provided: seed with the given value.
+ // If -s is not provided: seed with the PID and current time, which are unlikely
+ // to repeat simultaneously.
+ uint32_t seed_nr;
+ if (!seed) {
+ seed_nr = getpid();
+ } else {
+ seed_nr = seed_opt;
+ }
x = uint64_t(seed_nr) << 32;
x ^= uint64_t(depth) << 16;
@@ -182,16 +192,12 @@ int main(int argc, char **argv)
xorshift64star();
xorshift64star();
- if (!seed){
+ if (!seed) {
struct timeval tv;
gettimeofday(&tv, NULL);
x ^= uint64_t(tv.tv_sec) << 20;
x ^= uint64_t(tv.tv_usec);
}
- else {
- x ^= uint64_t(seed) << 20;
- x ^= uint64_t(seed);
- }
xorshift64star();
xorshift64star();