hash_str Function

private function hash_str(key) result(hash)

This is joaat_hash from string_table.F, generates the hash of a given string

Arguments

Type IntentOptional Attributes Name
character(len=*), intent(in) :: key

key a string of any length

Return Value integer(kind=int_8)


Contents

Source Code

hash_str

Source Code

FUNCTION hash_str(key) RESULT(hash)
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
   !! This is joaat_hash from string_table.F, generates the hash of a given string
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
   !! @note
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
   !!       http://en.wikipedia.org/wiki/Hash_table
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
   !!       http://www.burtleburtle.net/bob/hash/doobs.html
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"

# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
    CHARACTER(LEN=*), INTENT(IN)             :: key
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
       !! key a string of any length
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
    INTEGER(KIND=int_8)                      :: hash
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
    INTEGER(KIND=int_8), PARAMETER           :: b32 = 2_int_8**32-1_int_8
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
    INTEGER                                  :: i
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"

# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
    hash=0_int_8
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
    DO i=1,LEN(key)
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
       hash=IAND(hash+ICHAR(key(i:i))                ,b32)
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
       hash=IAND(     hash+IAND(ISHFT(hash,10),b32)  ,b32)
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
       hash=IAND(IEOR(hash,IAND(ISHFT(hash,-6),b32)) ,b32)
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
    ENDDO
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
    hash=IAND(     hash+IAND(ISHFT(hash,  3),b32)  ,b32)
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
    hash=IAND(IEOR(hash,IAND(ISHFT(hash,-11),b32)) ,b32)
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
    hash=IAND(     hash+IAND(ISHFT(hash, 15),b32)  ,b32)
# 111 "/__w/dbcsr/dbcsr/src/core/dbcsr_dict.F"
END FUNCTION hash_str