Cleanup GPU lifetime event histograms.
[chromium-blink-merge.git] / third_party / re2 / util / random.cc
blob49d6195876a31aaf5e3a0c7b0f2d16bbba7c64a1
1 // Copyright 2005-2009 The RE2 Authors. All Rights Reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
5 // Modified from Google perftools's tcmalloc_unittest.cc.
7 #include "util/random.h"
9 namespace re2 {
11 int32 ACMRandom::Next() {
12 const int32 M = 2147483647L; // 2^31-1
13 const int32 A = 16807;
14 // In effect, we are computing seed_ = (seed_ * A) % M, where M = 2^31-1
15 uint32 lo = A * (int32)(seed_ & 0xFFFF);
16 uint32 hi = A * (int32)((uint32)seed_ >> 16);
17 lo += (hi & 0x7FFF) << 16;
18 if (lo > M) {
19 lo &= M;
20 ++lo;
22 lo += hi >> 15;
23 if (lo > M) {
24 lo &= M;
25 ++lo;
27 return (seed_ = (int32) lo);
30 int32 ACMRandom::Uniform(int32 n) {
31 return Next() % n;
34 } // namespace re2