Module: GeneralHashFunctionsPure

Defined in:
lib/general-hash-functions.rb

Overview

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Class Method Summary collapse

Class Method Details

.aphash(str) ⇒ Object

Raises:

  • (NotImplementedError) 


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# File 'lib/general-hash-functions.rb', line 115

def self.aphash( str )
  raise NotImplementedError::new("Arash Partow's hash is provided by C extension only.")
end

.bkdrhash(str) ⇒ Object 



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# File 'lib/general-hash-functions.rb', line 57

def self.bkdrhash( str )
  seed = 131    # 31 131 1313 13131 131313 etc..
  hash = 0
  str.each_byte{ |i|
    hash = (( hash * seed ) + i) & 0xffffffff
  }
  return hash
end

.bphash(str) ⇒ Object 



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# File 'lib/general-hash-functions.rb', line 94

def self.bphash( str )
  hash = 0
  str.each_byte{ |i|
    hash = (hash << 7 ^ i) & 0xffffffff
  }
  return hash
end

.dekhash(str) ⇒ Object 



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# File 'lib/general-hash-functions.rb', line 85

def self.dekhash( str )
  hash = str.length
  str.each_byte{ |i|
    hash = (((hash << 5) ^ (hash >> 27)) ^ i) & 0xffffffff
  }
  return hash
end

.djbhash(str) ⇒ Object 



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# File 'lib/general-hash-functions.rb', line 76

def self.djbhash( str )
  hash = 5381
  str.each_byte{ |i|
    hash = (((hash << 5) + hash) + i) & 0xffffffff
  }
  return hash
end

.elfhash(str) ⇒ Object 



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# File 'lib/general-hash-functions.rb', line 42

def self.elfhash( str )
  hash = 0
  x = 0
  str.each_byte{ |i|
    hash = (hash << 4) + i
    if  (x = hash & 0xF0000000) != 0
      hash ^= (x >> 24)
      hash &= ~x
    end
    hash &= 0xffffffff
  }
  return hash
end

.fnvhash(str) ⇒ Object 



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# File 'lib/general-hash-functions.rb', line 103

def self.fnvhash( str )
  fnv_prime = 0x811C9DC5
  hash = 0
  str.each_byte{ |i|
    hash *= fnv_prime
    hash ^= i
    hash &= 0xffffffff
  }
  return hash
end

.jshash(str) ⇒ Object 



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# File 'lib/general-hash-functions.rb', line 33

def self.jshash( str )
  hash = 1315423911
  str.each_byte{ |i| 
    hash ^= ( ( hash << 5 ) + i + ( hash >> 2 ) ) & 0xffffffff
  }
  return hash
end

.rshash(str) ⇒ Object 



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# File 'lib/general-hash-functions.rb', line 21

def self.rshash( str )
  a    = 63689
  b    = 378551
  hash = 0
  str.each_byte{ |i| 
    hash = (hash * a + i) & 0xffffffff
    a = (a * b) & 0xffffffff
  }
  return hash
end

.sdbmhash(str) ⇒ Object 



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# File 'lib/general-hash-functions.rb', line 67

def self.sdbmhash( str )
  hash = 0
  str.each_byte{ |i|
    hash = (i + ( hash << 6 ) + ( hash << 16 ) - hash) & 0xffffffff
  }
  return hash
end