#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <math.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include "regex.h"

//Boyer Moore法に使用するテーブルを作成
int *
createBMskiptable(BMDataPtr bmdata)
{
    int searchWordLen = bmdata->searchWordLen;
    char *searchWord = bmdata->searchWord;
    int* skipTable = (int*)malloc(sizeof(int)*256);

    for(int i = 0; i < 256; ++i){
        bmdata->skipTable[i] = searchWordLen;
    }

    for(int j = 0; j < searchWordLen - 1; ++j){
        bmdata->skipTable[(u_char)searchWord[j]] = searchWordLen - j - 1;
    }
    return skipTable;
}

//Boyer Moore法による文字列検索アルゴリズム
void* BMmethod(BMDataPtr bmdata,ResultPtr result)
{
    int i = bmdata->searchWordLen - 1;
    int matchCounter = 0;

    while ( i < bmdata->readTextLen){
        int j = bmdata->searchWordLen - 1;
        while (bmdata->readText[i] == bmdata->searchWord[j]){
            if (j == 0){
                matchCounter++;
            }
            --i;
            --j;
        }
        i = i + fmax(bmdata->skipTable[(u_char)bmdata->readText[i]],bmdata->searchWordLen - j);
    }

    result->matchNum = matchCounter;
    return result;
}