1 /******************************************************************************* 2 * Copyright 2010-2018 Intel Corporation 3 * All Rights Reserved. 4 * 5 * If this software was obtained under the Intel Simplified Software License, 6 * the following terms apply: 7 * 8 * The source code, information and material ("Material") contained herein is 9 * owned by Intel Corporation or its suppliers or licensors, and title to such 10 * Material remains with Intel Corporation or its suppliers or licensors. The 11 * Material contains proprietary information of Intel or its suppliers and 12 * licensors. The Material is protected by worldwide copyright laws and treaty 13 * provisions. No part of the Material may be used, copied, reproduced, 14 * modified, published, uploaded, posted, transmitted, distributed or disclosed 15 * in any way without Intel's prior express written permission. No license under 16 * any patent, copyright or other intellectual property rights in the Material 17 * is granted to or conferred upon you, either expressly, by implication, 18 * inducement, estoppel or otherwise. Any license under such intellectual 19 * property rights must be express and approved by Intel in writing. 20 * 21 * Unless otherwise agreed by Intel in writing, you may not remove or alter this 22 * notice or any other notice embedded in Materials by Intel or Intel's 23 * suppliers or licensors in any way. 24 * 25 * 26 * If this software was obtained under the Apache License, Version 2.0 (the 27 * "License"), the following terms apply: 28 * 29 * You may not use this file except in compliance with the License. You may 30 * obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 31 * 32 * 33 * Unless required by applicable law or agreed to in writing, software 34 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 35 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 36 * 37 * See the License for the specific language governing permissions and 38 * limitations under the License. 39 *******************************************************************************/ 40 41 /* 42 // Intel(R) Integrated Performance Primitives. Cryptography Primitives. 43 // Internal operations over GF(p) extension. 44 // 45 // Context: 46 // cpGFpGetOptimalWinSize() 47 // 48 */ 49 50 #include "owncp.h" 51 #include "pcpbnumisc.h" 52 #include "pcpgfpxstuff.h" 53 #include "gsscramble.h" 54 55 static int div_upper(int a, int d) 56 { return (a+d-1)/d; } 57 58 static int getNumOperations(int bitsize, int w) 59 { 60 int n_overhead = (1<<w) -1; 61 int n_ops = div_upper(bitsize, w) + n_overhead; 62 return n_ops; 63 } 64 65 int cpGFpGetOptimalWinSize(int bitsize) 66 { 67 int w_opt = 1; 68 int n_opt = getNumOperations(bitsize, w_opt); 69 int w_trial; 70 for(w_trial=w_opt+1; w_trial<=IPP_MAX_EXPONENT_NUM; w_trial++) { 71 int n_trial = getNumOperations(bitsize, w_trial); 72 if(n_trial>=n_opt) break; 73 w_opt = w_trial; 74 n_opt = n_trial; 75 } 76 return w_opt; 77 } 78
