The fmemcmpi() function compares the two memory areas,
the size1 bytes pointed to by data1 and
the size2 bytes pointed to by data2.
RETURN VALUE
The fmemcmpi function returns an int value between
0 and FSTRCMPI_IDENTICAL. A value of 0 means the memory areas are
utterly un-alike. A value of FSTRCMPI_IDENTICAL means the memory areas are
identical. A value of more than FSTRCMPI_THRESHOLD (it lies between 0.0
and FSTRCMP_IDENTICAL) would be considered "similar" by most people.
A value of FSTRCMPI_ERROR (always negative) indicates a malloc(3)
failure.
The comparison code is derived from the fuzzy comparison functions in
GNU Gettext 0.17. The GNU Gettext comparison functions were, in turn,
derived from GNU Diff 2.7.