RS Image Hash Function [378]

19
LINES

< > BotCompany Repo | #378 // RS Image Hash Function

Lua code

get("#356") -- num2hex

function RSHash(img)
  local b, a, hash = 378551, 63689, 0
  local w, h = img.width, img.height
  
  for y = 0, h-1 do
    for x = 0, w-1 do
      local pix = img.getInt(x, y)
      --hash = (hash * a + pix) % 0x100000000
      --a = (a * b) % 0x100000000
      hash = bit32.band(hash * a + pix, 0xFFFFFFFF)
      a = bit32.band(a * b, 0xFFFFFFFF)
    end
  end
  
  print("rshash: a=", a)
  return num2hex(hash, 8)
end

Author comment

originally from http://www.partow.net/programming/hashfunctions/ - might have different results

test run test run with input download show line numbers

Travelled to 12 computer(s): aoiabmzegqzx, bhatertpkbcr, cbybwowwnfue, gwrvuhgaqvyk, ishqpsrjomds, lpdgvwnxivlt, mqqgnosmbjvj, pyentgdyhuwx, pzhvpgtvlbxg, tslmcundralx, tvejysmllsmz, vouqrxazstgt

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Snippet ID:	#378
Snippet name:	RS Image Hash Function
Eternal ID of this version:	#378/1
Text MD5:	e6a0e122f12fe2317f4e7d8e916e0754
Author:	stefan
Category:	hash functions
Type:	Lua code
Public (visible to everyone):	Yes
Archived (hidden from active list):	No
Created/modified:	2015-02-01 21:47:53
Source code size:	461 bytes / 19 lines
Pitched / IR pitched:	No / Yes
Views / Downloads:	715 / 163
Referenced in:	[show references]

1	get("#356") -- num2hex
2
3	function RSHash(img)
4	local b, a, hash = 378551, 63689, 0
5	local w, h = img.width, img.height
6
7	for y = 0, h-1 do
8	for x = 0, w-1 do
9	local pix = img.getInt(x, y)
10	--hash = (hash * a + pix) % 0x100000000
11	--a = (a * b) % 0x100000000
12	hash = bit32.band(hash * a + pix, 0xFFFFFFFF)
13	a = bit32.band(a * b, 0xFFFFFFFF)
14	end
15	end
16
17	print("rshash: a=", a)
18	return num2hex(hash, 8)
19	end