partial hcc file reader

#include <stdio.h>
#include <time.h>

#pragma pack(1)
struct record {
    int separator;
    int time;
    double open, high, low, close;
    char additional[10];
};

int main(void) {
    FILE *fp;
    struct record data;
    int i, extra1, extra2;
    time_t time;
    struct tm *tm;
    char timebuf[80];

    if ((fp=fopen("2015.hcc", "rb"))==NULL) {
        perror("2015.hcc"); exit(1);
    }
    // fseek(fp, 0x3be5, 0);
    fseek(fp, 0xde1a, 0);
    for (;;) {
        if (fread(&data, sizeof(int), 1, fp)==0)
            break;
        if ((data.separator & 0x00188884) != 0x00188884) {
            fprintf(stderr, "bad separator at %lx\n", ftell(fp));
            break;
        }
        extra1=data.separator>>28;
        extra2=((data.separator>>24)&0x0f)-1;
        fread(&data.time, sizeof(data)
                -sizeof(data.separator)
                -sizeof(data.additional)
                +2 // 2 bytes seem always to be there
                +extra1+extra2
            , 1, fp);
        time=data.time;
        tm=localtime(&time);
        strftime(timebuf, sizeof timebuf, "%Y-%m-%d %H:%M:%S", tm);
        printf("%s %lf %lf %lf %lf ", timebuf, data.open,
            data.high, data.low, data.close);
        for (i=0; i<extra1+extra2+2; i++) {
            printf("%3d ", data.additional[i]&0xff);
        }
        putchar('\n');
    }
    fclose(fp);
}