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author | whitequark <whitequark@whitequark.org> | 2020-06-26 10:44:40 +0000 |
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committer | whitequark <whitequark@whitequark.org> | 2020-06-26 11:30:00 +0000 |
commit | f8b8ea0f3cdc4a2cf61a28c1ce44616555b62e4e (patch) | |
tree | 57bc2df0f567f054e77f8c38031254119f0989f1 | |
parent | 3205180fd93d6abd1e63f5d8b794881896f57493 (diff) | |
download | icestorm-f8b8ea0f3cdc4a2cf61a28c1ce44616555b62e4e.tar.gz icestorm-f8b8ea0f3cdc4a2cf61a28c1ce44616555b62e4e.tar.bz2 icestorm-f8b8ea0f3cdc4a2cf61a28c1ce44616555b62e4e.zip |
icebram: refactor seeding logic.
-rw-r--r-- | icebram/icebram.cc | 22 |
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(); |