extracting rom files from rombank.bin from imbnes psx iso image

extract_rombank.c

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

typedef struct
{
        char name[0x1C];
        unsigned short offset;
        unsigned short size;
} gl_t;

size_t getFilesize(const char* filename) {
    struct stat st;
    stat(filename, &st);
    return st.st_size;
}

int main(int argc, char** argv) {
    size_t filesize = getFilesize(argv[1]);
    int fd = open(argv[1], O_RDONLY, 0);
    assert(fd != -1);
    void* md = mmap(NULL, filesize, PROT_READ, MAP_PRIVATE | MAP_POPULATE, fd, 0);

    char name[0x1C], fname[0x1c+16];
    gl_t* gl = md;
    for (int i=0; i<atoi(argv[2]); ++i)
    {
        strncpy(name, gl[i].name, 0x1c);
        name[0x1c-1] = 0;
        int j=0x1c-2;
        while(j>1)
        {
            if (name[j] == ' ')
                name[j] = 0;
            else
                break;
            j--;
        }
        sprintf(fname, "%04d %s.nes", i, name);

        printf("%d %hx %hx %s\n", i, gl[i].offset, gl[i].size, name);
        fsync(1);
        FILE *f = fopen(fname, "w");
        fwrite(md+gl[i].offset*2048, gl[i].size*0x80, 1, f);
        fclose(f);
    }

    int rc = munmap(md, filesize);
    assert(rc == 0);
    close(fd);
}

Can you please explain to me how to use it?

Do you have any videos on how to use it? Or the final executable?