crc32_hash Interface

crc32_hash(3f) - [M_hashkeys] CRC (Cyclic Redundancy Check)
(LICENSE:PD)

class(*),intent(in)          :: anything(:)
logical,intent(in),optional  :: continue
integer(int64)               :: crc_out

This ia 32-bit version of the Cyclic Redundancy Check(CRC).
This variant of CRC-32 uses LSB-first order, sets the initial CRC to
FFFFFFFF_int32, and complements the final CRC.

The result should be in accordance with ISO 3309, ITU-T V.42, Gzip
and PNG.

anything  input value to generate a CRC check for. May be a array
          or scalar of numeric or string values of type CHARACTER,
          int8, int16, int32, int64, real32, real64, real128
continue  optional parameter. If not present or .F. starts new
          CRC sum. If .T. continues a CRC starting with last CRC
          calculated.

crc       The calculated CRC sum. It is calculated as a 32-bit value
          but returned as a 64-bit value, as Fortran does not
          currently support unsigned integers.

Algorithms are described in "Computation of CRC" in Wikipedia.
Also see

   https://en.wikipedia.org/wiki/Cyclic_redundancy_check

This was derived from an unattributed example on http://rosettacode.org,
but has been modified.

program demo_crc32_hash
use,intrinsic :: ISO_FORTRAN_ENV, only : int64
use M_hashkeys, only : crc32_hash
implicit none
integer :: i
integer(int64) :: crc
character(*), parameter :: s = "The quick brown fox jumps over the lazy dog"
   ! string
   crc=crc32_hash(s)
   print "(Z8)", crc
   print "(i0)", crc
   ! character array
   print "(i0)", crc32_hash([ &
           & 'T','h','e',' ',&
           & 'q','u','i','c','k',' ',&
           & 'b','r','o','w','n',' ',&
           & 'f','o','x',' '])
   print "(i0)", crc32_hash([ &
           & 'j','u','m','p','s',' ',&
           & 'o','v','e','r',' ',&
           & 't','h','e',' ',&
           & 'l','a','z','y',' ',&
           & 'd','o','g'],continue=.true.)
   ! numeric array
   print "(i0)", crc32_hash([(i,i=1,100)])
end program demo_crc32_hash

414FA339
1095738169
2293265890
1095738169
1783575711