Merge pull request #499 from htlxyz/master

add bit module

framework/cc/utils/ByteArrayVarint.lua

@@ -11,7 +11,7 @@ Creation: 2013-11-14
 ]]
 local ByteArrayVarint = class("BitVaiant", import(".ByteArray"))
 
-require("bit")
+import(".bit")
 
 function ByteArrayVarint:ctor(__endian)
 	self._endian = __endian

framework/cc/utils/bit.lua

@@ -0,0 +1,260 @@
+--[[---------------
+LuaBit v0.4
+-------------------
+a bitwise operation lib for lua.
+
+http://luaforge.net/projects/bit/
+
+How to use:
+-------------------
+ bit.bnot(n) -- bitwise not (~n)
+ bit.band(m, n) -- bitwise and (m & n)
+ bit.bor(m, n) -- bitwise or (m | n)
+ bit.bxor(m, n) -- bitwise xor (m ^ n)
+ bit.brshift(n, bits) -- right shift (n >> bits)
+ bit.blshift(n, bits) -- left shift (n << bits)
+ bit.blogic_rshift(n, bits) -- logic right shift(zero fill >>>)
+ 
+Please note that bit.brshift and bit.blshift only support number within
+32 bits.
+
+2 utility functions are provided too:
+ bit.tobits(n) -- convert n into a bit table(which is a 1/0 sequence)
+               -- high bits first
+ bit.tonumb(bit_tbl) -- convert a bit table into a number 
+-------------------
+
+Under the MIT license.
+
+copyright(c) 2006~2007 hanzhao ([email protected])
+--]]---------------
+
+do
+
+------------------------
+-- bit lib implementions
+
+local function check_int(n)
+ -- checking not float
+ if(n - math.floor(n) > 0) then
+  error("trying to use bitwise operation on non-integer!")
+ end
+end
+
+local function to_bits(n)
+ check_int(n)
+ if(n < 0) then
+  -- negative
+  return to_bits(bit.bnot(math.abs(n)) + 1)
+ end
+ -- to bits table
+ local tbl = {}
+ local cnt = 1
+ while (n > 0) do
+  local last = math.mod(n,2)
+  if(last == 1) then
+   tbl[cnt] = 1
+  else
+   tbl[cnt] = 0
+  end
+  n = (n-last)/2
+  cnt = cnt + 1
+ end
+
+ return tbl
+end
+
+local function tbl_to_number(tbl)
+ local n = table.getn(tbl)
+
+ local rslt = 0
+ local power = 1
+ for i = 1, n do
+  rslt = rslt + tbl[i]*power
+  power = power*2
+ end
+
+ return rslt
+end
+
+local function expand(tbl_m, tbl_n)
+ local big = {}
+ local small = {}
+ if(table.getn(tbl_m) > table.getn(tbl_n)) then
+  big = tbl_m
+  small = tbl_n
+ else
+  big = tbl_n
+  small = tbl_m
+ end
+ -- expand small
+ for i = table.getn(small) + 1, table.getn(big) do
+  small[i] = 0
+ end
+
+end
+
+local function bit_or(m, n)
+ local tbl_m = to_bits(m)
+ local tbl_n = to_bits(n)
+ expand(tbl_m, tbl_n)
+
+ local tbl = {}
+ local rslt = math.max(table.getn(tbl_m), table.getn(tbl_n))
+ for i = 1, rslt do
+  if(tbl_m[i]== 0 and tbl_n[i] == 0) then
+   tbl[i] = 0
+  else
+   tbl[i] = 1
+  end
+ end
+
+ return tbl_to_number(tbl)
+end
+
+local function bit_and(m, n)
+ local tbl_m = to_bits(m)
+ local tbl_n = to_bits(n)
+ expand(tbl_m, tbl_n) 
+
+ local tbl = {}
+ local rslt = math.max(table.getn(tbl_m), table.getn(tbl_n))
+ for i = 1, rslt do
+  if(tbl_m[i]== 0 or tbl_n[i] == 0) then
+   tbl[i] = 0
+  else
+   tbl[i] = 1
+  end
+ end
+
+ return tbl_to_number(tbl)
+end
+
+local function bit_not(n)
+
+ local tbl = to_bits(n)
+ local size = math.max(table.getn(tbl), 32)
+ for i = 1, size do
+  if(tbl[i] == 1) then 
+   tbl[i] = 0
+  else
+   tbl[i] = 1
+  end
+ end
+ return tbl_to_number(tbl)
+end
+
+local function bit_xor(m, n)
+ local tbl_m = to_bits(m)
+ local tbl_n = to_bits(n)
+ expand(tbl_m, tbl_n) 
+
+ local tbl = {}
+ local rslt = math.max(table.getn(tbl_m), table.getn(tbl_n))
+ for i = 1, rslt do
+  if(tbl_m[i] ~= tbl_n[i]) then
+   tbl[i] = 1
+  else
+   tbl[i] = 0
+  end
+ end
+
+ --table.foreach(tbl, print)
+
+ return tbl_to_number(tbl)
+end
+
+local function bit_rshift(n, bits)
+ check_int(n)
+
+ local high_bit = 0
+ if(n < 0) then
+  -- negative
+  n = bit_not(math.abs(n)) + 1
+  high_bit = 2147483648 -- 0x80000000
+ end
+
+ for i=1, bits do
+  n = n/2
+  n = bit_or(math.floor(n), high_bit)
+ end
+ return math.floor(n)
+end
+
+-- logic rightshift assures zero filling shift
+local function bit_logic_rshift(n, bits)
+ check_int(n)
+ if(n < 0) then
+  -- negative
+  n = bit_not(math.abs(n)) + 1
+ end
+ for i=1, bits do
+  n = n/2
+ end
+ return math.floor(n)
+end
+
+local function bit_lshift(n, bits)
+ check_int(n)
+
+ if(n < 0) then
+  -- negative
+  n = bit_not(math.abs(n)) + 1
+ end
+
+ for i=1, bits do
+  n = n*2
+ end
+ return bit_and(n, 4294967295) -- 0xFFFFFFFF
+end
+
+local function bit_xor2(m, n)
+ local rhs = bit_or(bit_not(m), bit_not(n))
+ local lhs = bit_or(m, n)
+ local rslt = bit_and(lhs, rhs)
+ return rslt
+end
+
+--------------------
+-- bit lib interface
+
+bit = {
+ -- bit operations
+ bnot = bit_not,
+ band = bit_and,
+ bor  = bit_or,
+ bxor = bit_xor,
+ brshift = bit_rshift,
+ blshift = bit_lshift,
+ bxor2 = bit_xor2,
+ blogic_rshift = bit_logic_rshift,
+
+ -- utility func
+ tobits = to_bits,
+ tonumb = tbl_to_number,
+}
+
+end
+
+--[[
+for i = 1, 100 do
+ for j = 1, 100 do
+  if(bit.bxor(i, j) ~= bit.bxor2(i, j)) then
+   error("bit.xor failed.")
+  end
+ end
+end
+--]]
+
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