Compute Hash32 value from ulong, long, ulongint,longint, single, double, pointer, string and zstring ptr

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D.J.Peters
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Joined: May 28, 2005 3:28
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Compute Hash32 value from ulong, long, ulongint,longint, single, double, pointer, string and zstring ptr

Post by D.J.Peters »

Original link www.concentric.net/~Ttwang/tech/inthash.htm are down but i found it on web.archive.org :-)
web.archive.org: http://www.concentric.net/~Ttwang/tech/inthash.htm

Jolshy

Code: Select all

' Hash functions
' http://web.archive.org/web/20071223173210/http://www.concentric.net/~Ttwang/tech/inthash.htm
function ComputeHash overload(byref key as const ulong) as ulong
  dim as ulong k = key,t=k shl 15
  k += not t : t = k shr 10
  k xor =  t : t = k shl  3
  k +=     t : t = k shr  6
  k xor =  t : t = k shl 11
  k += not t : t = k shr  6
  k xor =  t
  return k
end function

function ComputeHash(byref key as const long) as ulong
  return ComputeHash(cast(ulong,key))
end function

function ComputeHash(byref key as const ulongint) as ulong
  dim as ulongint k = key, t = k shl 32
  k += not t : t = k shr 22
  k xor =  t : t = k shl 13
  k += not t : t = k shr  8
  k xor =  t : t = k shl  3
  k +=     t : t = k shr 15
  k xor =  t : t = k shl 27
  k += not t : t = k shr 31
  k xor =  t
  k and= &HFFFFFFFF
  return k
end function

function ComputeHash(byref key as const longint) as ulong
  dim as ulongint k=key
  return ComputeHash(k)
end function  
  
function ComputeHash(byref f as const single) as ulong
  return ComputeHash(*cptr(ulong ptr,@f))
end function  

function ComputeHash(byref d as const double) as ulong
  return ComputeHash(*cptr(ulongint ptr,@d))
end function  

function ComputeHash(byval p as any ptr) as ulong
#ifndef __FB_64BIT__
  return ComputeHash(cast(ulong,p))
#else
  return ComputeHash(cast(ulongint,p))
#endif
end function

function ComputeHash(byref s as string) as ulong
  dim as ulong h = 5381,nChars=len(s),u32
  if nChars then
    nChars-=1
    for i as uinteger=0 to nChars
      u32 = s[i] : h = ((h shl 5) + h) xor u32
    next  
    return h
  endif
  return 0
end function

function ComputeHash(byref s as const zstring ptr) as ulong
  dim as ulong h = 5381
  if s then
    dim as ulong nChars=len(s),u32
    if nChars then
      nChars-=1
      for i as uinteger=0 to nChars
        u32 = s[i] : h = ((h shl 5) + h) xor u32
      next
      return h
    endif    
  endif  
  return 0
end function

dim as ulong    u32 = 1234
dim as long     s32 =-1234
dim as ulongint u64 = 12345678
dim as ulongint s64 =-12345678
dim as single   f32 = 123.456
dim as double   f64 = 123.45678
dim as string   s = "Hello, world!"
dim as any ptr  p = strptr(s)

print "u32 hash(u32): 0x" & hex(ComputeHash(u32),8)
print "u32 hash(s32): 0x" & hex(ComputeHash(s32),8)
print "u32 hash(u64): 0x" & hex(ComputeHash(u64),8)
print "u32 hash(s64): 0x" & hex(ComputeHash(s64),8)
print "u32 hash(f32): 0x" & hex(ComputeHash(f32),8)
print "u32 hash(f64): 0x" & hex(ComputeHash(f64),8)
print "u32 hash(ptr): 0x" & hex(ComputeHash(p),8)
print "u32 hash(str): 0x" & hex(ComputeHash(s),8)
print 

function u32_2_float(byval value as ulong) as single
  dim as ulong  u32 = &H3F800000 or (value and &H3FFFFFFF)                         
  dim as single f32 = *cptr(single ptr, @u32)
  return f32 - 1.0f
end function

print "f32 hash(u32): " & u32_2_float(ComputeHash(u32))
print "f32 hash(s32): " & u32_2_float(ComputeHash(s32))
print "f32 hash(u64): " & u32_2_float(ComputeHash(u64))
print "f32 hash(s64): " & u32_2_float(ComputeHash(s64))
print "f32 hash(f32): " & u32_2_float(ComputeHash(f32))
print "f32 hash(f64): " & u32_2_float(ComputeHash(f64))
print "f32 hash(ptr): " & u32_2_float(ComputeHash(p))
print "f32 hash(str): " & u32_2_float(ComputeHash(s))
sleep
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