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/*
// Copyright (c) 2010-2017 Intel Corporation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
*/
struct cdf {
uint32_t rand_max;
uint32_t seed;
uint32_t first_child;
uint32_t elems[0];
};
struct cdf *cdf_create(uint32_t n_vals, int socket_id);
void cdf_add(struct cdf *cdf, uint32_t len);
int cdf_setup(struct cdf *cdf);
static uint32_t cdf_sample(struct cdf *cdf)
{
uint32_t left_child, right_child;
uint32_t rand;
do {
rand = rand_r(&cdf->seed);
} while (rand > cdf->rand_max);
uint32_t cur = 1;
while (1) {
left_child = cur * 2;
right_child = cur * 2 + 1;
if (right_child < cdf->elems[0])
cur = rand > cdf->elems[cur]? right_child : left_child;
else if (left_child < cdf->elems[0])
cur = left_child;
else
return cur - cdf->first_child;
}
}
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