文字の比較速度

#include <stdio.h>
#include <string.h>
#include <limits.h>
#include "stopwatch.h"

char flags[256] = { 0 };

#define isspace(c) (flags[(unsigned char)(c)])
#define MAXFSIZE 4000000
#define FNAME "test.res"
#define MAXLOOP 10000000

#define MODE   OR2
#define TABLE  1
#define SWITCH 2
#define OR1    3
#define OR2    4

size_t filetostr(const char *fname, char *buf);

size_t filetostr(const char *fname, char *buf)
{
    FILE *fp;
    size_t retval;

    if (fopen_s(&fp, fname, "rt")) {
        printf("Cannot open file %s.\n", fname);
        return 0;
    }
    retval = fread(buf, 1, MAXFSIZE, fp);
    fclose(fp);
    return retval;
}

void main()
{
    char *pos, *end;
    char *str;
    int skip;
    int cnt;
    stopwatch_t timer;
    double d;

    if (!(str = malloc(MAXFSIZE))) exit(0);
    end = str + filetostr(FNAME, str);

    flags[' '] = 1;
    flags['\t'] = 1;
    flags['\n'] = 1;
    flags['#'] = 1;
    flags['0'] = 1;

    stopwatchInit(&timer);
    stopwatch(&timer);

    for (cnt = 0; cnt < MAXLOOP; cnt++) {
        for (skip = 0, pos = str; pos < end; pos++) {

#if MODE == TABLE

            skip = (isspace(*pos));

#elif MODE == SWITCH

            switch (*pos) {
            case ' ':
            case '\t':
            case '\n':
            case '#':
            case '0':
                skip = 1;
                break;
            default:
                skip = 0;
            }

#elif MODE == OR1

            skip = ((*pos == ' ') || (*pos == '\t') || (*pos == '\n') || (*pos == '#') || (*pos == '0'));

#elif MODE == OR2

            skip = (*pos == ' ');

#endif //MODE

        }
    }

    d = stopwatch(&timer);
    putc(skip, stdout);
    printf("Compare done. Mode = %d. Took %f ms.\n", MODE, d);
}