NOR Flash EFS fopen() passes invalid address to flash driver

The base address of the NOR flash is 0. Isn't the base address part of the FlashInfo structure shown above?

The NOR flash was not blank. The chip erase failed. After fixing this issue I was able to use fopen().

Questions:

1. How can you determine if the file system has been initialized?
   1. finit() and fmount() always complete successfully. 
   2. fopen() assumes the flash contents have been initialized and may attempt to read invalid addresses
2. Does the flash file system do wear leveling?

  FILE *f = fopen(DRIVE "\\ao2.cfg","rw");
  if (f == NULL) {
    printf("Error (%d) opening ao2config.bin\n", errno);
    f = fopen(DRIVE "\\ao2.cfg","w");
    if (f == NULL) {
      printf("Error (%d) creating ao2.cfg\n", errno);
    } else {
      //f = freopen("\\ao2.cfg","rw",f);
      fseek(f, 100, SEEK_SET);
      long pos = ftell(f);
      fseek(f, 0, SEEK_SET);
      memset(protbuf, 0x55, sizeof(protbuf));
      size_t wt = fwrite(protbuf, sizeof(protbuf), 1, f);
      fseek(f, 0, SEEK_SET);
      memset(protbuf, 0x00, sizeof(protbuf));
      size_t rt = fread(protbuf, sizeof(protbuf), 1, f);
      fflush(f);
      fclose(f);
    }
  }

Observations:

• don't seem to be able to open file in read and write. "rw" mode acts like "r"
• opening file in write mode will create the file
• write will not extend the file. You must use fseek() to expand the file. Then go back to write the data.
• write mode does not allow read. How do you open in R/W mode