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Rydian
Grandmaster Cheater Supreme
 Reputation: 31
Joined: 17 Sep 2012
Posts: 1358
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 Posted: Wed Apr 29, 2015 1:03 am Post subject: Read/display/format a single bit. |
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So there's readFloat, readInteger, readDouble, etc.
But there's no functions for reading 2-byte values, single-byte values, or single bits.
2-byte and single-byte can be gotten doing a band with 0xFFFF or 0xFF, but how would I go about getting the value of individual bits to display?
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Dark Byte
Site Admin
 Reputation: 458
Joined: 09 May 2003
Posts: 25291
Location: The netherlands
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| Posted: Wed Apr 29, 2015 2:53 am Post subject: |
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| Code: |
function isBitSet(value, bitnumber)
return bAnd(value, bShl(1,bitnumber)) ~= 0
end
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panraven
Grandmaster Cheater
![]() Reputation: 55
Joined: 01 Oct 2008
Posts: 942
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| Posted: Wed Apr 29, 2015 5:04 am Post subject: |
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made a heavy bitfield function:
| Code: | function bitField(a,b)-- a,b < 64, bit number is zero based
local function isInteger(p) return type(p)=='number' and math.floor(p) == p end
assert(isInteger(a) and a >= 0 and a < 64, '1st arg must be integer between 0 and 63 inclusive')
b = type(b)=='number' and math.floor(b)==b and b >= 0 and b < 64 and b or a -- default 1 bit bit-field (a,a)
if a > b then a,b = b,a end -- made sure a <= b
return function(v,Address)
local Addr = Address or nil
if Addr and readQword(Addr) then -- read value from address if address specificied
v = readQword(Addr)
else
v = isInteger(v) and v or 0 -- default value 0 on initialize
end
local this = {}
local Cache,Value =nil, v
function this:get()
if Cache == nil then
Cache = 0
local n,m = 1,2^a
for i=a,b do
if bAnd(Value,m)~=0 then Cache = Cache + n end
n,m = 2 * n,2 *m
end
end
return Cache
end
function this:set(p)
assert(isInteger(p),'Integer needed')
local n,m = 1,2^a
for i=a,b do
local bm,bn = bAnd(Value,m), bAnd(p,n)
if bm~=bShl(bn,a) then
Value = bn == 0 and Value - bm or Value + bShl(bn,a)
Cache = nil -- reset cache
end
n,m = 2*n,2 *m
end
return self
end
function this:getValue() return Value end
function this:setValue(v)
assert(isInteger(v),'Integer needed')
Cache,Value = nil,v
return self
end
function this:read(addr)
addr = addr or Addr
this:setValue(readQword(addr))
return self
end
function this:write(addr) -- caution if value at addr changed during modifying bit field
addr = addr or Addr
writeQword(addr,this:getValue())
return self
end
return this
end
end
-- test
local bf2_5 = bitField(2,5) -- bf2_5 is a function to create bitfield 2bit-5bit object
local bf = bf2_5()
print(bf:get())
bf = bf2_5(0xaf)
print(bf:get()) --- 10(1011)11 --> bf(2,5)= 1011 = 11
bf:set(7) -- change to 10(0111)11 -> value = 0x9f = 159
print(bf:getValue())
bf:setValue(0xff)
print(bf:get()) --- 11(1111)11 --> bf(2,5)= 1111 = 15
autoAssemble('globalalloc(TESTZONE,256)')
writeInteger('TESTZONE',-1)
writeInteger('TESTZONE+04',16)
bf = bf2_5(nil,'TESTZONE')
local shex = function(n) return string.format('%02X',n) end
print('before write memory:',shex(bf:getValue())) -- should be 0x10ffffffff, coz getValue return 64-bit integer
bf:read():set(0):write() -- read address again, change bit field, write it back to memory
print(' after write memory:',shex(readInteger('TESTZONE'))) -- should be 0xffffffc3
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