I'm attempting to create a Lua program to monitor periodic status pings of a slave device. The slave device sends its status in 16-bit hexadecimal words, which I need to convert to a binary string since each bit pertains to a property of the device. I can receive the input string, and I have a table containing 16 keys for each parameter. But I am having a difficult time understanding how to convert the hexadecimal word into a string of 16-bits so I can monitor it.
Here is a basic function of what I'm starting to work on.
function slave_Status(IP,Port,Name)
status = path:read(IP,Port)
sTable = {}
if status then
sTable.ready=bit32.rshift(status:byte(1), 0)
sTable.paused=bit32.rshift(status:byte(1), 1)
sTable.emergency=bit32.rshift(status:byte(1), 2)
sTable.started=bit32.rshift(status:byte(1), 3)
sTable.busy=bit32.rshift(status:byte(1), 4)
sTable.reserved1=bit32.rshift(status:byte(1), 5)
sTable.reserved2=bit32.rshift(status:byte(1), 6)
sTable.reserved3=bit32.rshift(status:byte(1), 7)
sTable.reserved4=bit32.rshift(status:byte(2), 0)
sTable.delay1=bit32.rshift(status:byte(2), 1)
sTable.delay2=bit32.rshift(status:byte(2), 2)
sTable.armoff=bit32.rshift(status:byte(2), 3)
sTable.shieldoff=bit32.rshift(status:byte(2), 4)
sTable.diskerror=bit32.rshift(status:byte(2), 5)
sTable.conoff=bit32.rshift(status:byte(2), 6)
sTable.envoff=bit32.rshift(status:byte(2), 7)
end
end
I hope this approach is understandable? I'd like to receive the Hex strings, for example 0x18C2 and turn that to 0001 1000 1100 0010, shifting the right-most bit to the right and placing that into the proper key. Then later in the function I would monitor if that bit had changed for the better or worse.
If I run a similar function in Terminator in Linux, and print out the pairs I get the following return:
49
24
12
6
3
1
0
0
56
28
14
7
3
1
0
0
This is where I am not understanding how to take each value and set it to bits
I'm pretty new to this so I do not doubt that there is an easier way to do this. If I need to explain further I will try.
tonumber(s, 16) will convert hex representation to decimal and string.char will return a symbol/byte representation of a number. Check this recent SO answer for an example of how they can be used; the solution in the answer may work for you.
I'd approach this in a different fashion than the one suggested by Paul.
First, create a table storing the properties of devices:
local tProperty = {
"ready",
"paused",
"emergency",
"started",
"busy",
"reserved1",
"reserved2",
"reserved3",
"reserved4",
"delay1",
"delay2",
"armoff",
"shieldoff",
"diskerror",
"conoff",
"envoff",
}
Then, since your device sends the data as 0xYYYY, you can call tonumber directly (if not a string). Use a function to store each bit in a table:
function BitConvert( sInput )
local tReturn, iNum = {}, tonumber( sInput ) -- optionally pass 16 as second argument to tonumber
while iNum > 0 do
table.insert( tReturn, 1, iNum % 2 )
iNum = math.floor( iNum / 2 )
end
for i = #tProperty - #tReturn, 1, -1 do
table.insert( tReturn, 1, 0 )
end
return tReturn
end
And then, map both the tables together:
function Map( tKeys, tValues )
local tReturn = {}
for i = 1, #tKeys do
tReturn[ tKeys[i] ] = tValues[i]
end
return tReturn
end
In the end, you would have:
function slave_Status( IP, Port, Name )
local status = path:read( IP, Port )
local sTable = Map( tProperty, BitConvert(status) )
end
Related
I have an binary file with shows glibberish infos if i open it in Notepad.
I am working on an plugin to use with wireshark.
So my problem is that I need help. I am reading in an File and need to find 'V' '0' '0' '1' (0x56 0x30 0x30 0x31) in the File, because its the start of an Header, with means there is an packet inside. And I need to do this for the whole file, like parsing. Also should start the Frame with V 0 0 1 and not end with it.
I currently have an Code where I am searching for 0x7E and parse it. What I need is the length of the frame. For example V 0 0 1 is found, so the Length from V to the Position before the next V 0 0 1 in the File. So that I can work with the length and add it to an captured length to get the positions, that wireshark can work with.
For example my unperfect Code for working with 0x7E:
local line = file:read()
local len = 0
for c in (line or ''):gmatch ('.') do
len = len + 1
if c:byte() == 0x7E then
break
end
end
if not line then
return false
end
frame.captured_length = len
Here is also the Problem that the Frame ends with 7E which is wrong. I need something that works perfectly for 'V' '0' '0' '1'. Maybe I need to use string.find?
Please help me!
Thats an example how my file looks like if i use the HEX-Editor in Visual Studio Code.
Lua has some neat pattern tools. Here's a summary:
(...) Exports all captured text within () and gives it to us.
-, +, *, ?, "Optional match as little as possible", "Mandatory match as much as possible", "optional match as much as possible", "Optional match only once", respectively.
^ and $: Root to start or end of file, respectively.
We'll be using this universal input and output to test with:
local output = {}
local input = "V001Packet1V001Packet2oooV001aaandweredonehere"
The easiest way to do this is probably to recursively split the string, with one ending at the character before "V", and the other starting at the character after "1". We'll use a pattern which exports the part before and after V001:
local this, next = string.match(input, "(.-)V001(.*)")
print(this,next) --> "", "Packet1V001Packet2..."
Simple enough. Now we need to do it again, and we also need to eliminate the first empty packet, because it's a quirk of the pattern. We can probably just say that any empty this string should not be added:
if this ~= "" then
table.insert(output, this)
end
Now, the last packet will return nil for both this and next, because there will not be another V001 at the end. We can prepare for that by simply adding the last part of the string when the pattern does not match.
All put together:
local function doStep(str)
local this, next = string.match(str, "(.-)V001(.*)")
print(this,next)
if this then
-- There is still more packets left
if this ~= "" then
-- This is an empty packet
table.insert(output, this)
end
if next ~= "" then
-- There is more out there!
doStep(next)
end
else
-- We are the last survivor.
table.insert(output, str)
end
end
Of course, this can be improved, but it should be a good starting point. To prove it works, this script:
doStep(input)
print(table.concat(output, "; "))
prints this:
Packet1; Packet2ooo; aaandweredonehere
I'm trying to create aggregation (map | reduce) with UDF but something is wrong on the very begining. In Aerospike I have a set with bin 'u' (secondary index) and bin 'v' which is a list of objects (auctions with transactions lists and other auction data) and I have a stream UDF to aggregate internal structure of 'v':
function trans_sum_by_years(s)
local function transform(rec)
local l = map()
local x = map()
local trans, auctions = 0, 0
for i in list.iterator(rec['v'] or list()) do
auctions = auctions + 1
for t in list.iterator(i['t'] or list()) do
trans = trans + 1
date = os.date("*t", t['ts'])
if l[date['year']] ~= nil then
l[date['year']] = l[date['year']] + t['price'] * t['qty']
else
l[date['year']] = t['price'] * t['qty']
end
end
end
x.auctions = auctions
x.trans = trans
x.v = l
return x
end
return s : map(transform)
end
The problem is that output is very diffrent depending on setting output on table or json. In first case it seems everything is OK:
{"trans":594, "auctions":15, "v":{2010:1131030}}
{"trans":468, "auctions":68, "v":{2011:1472976, 2012:5188}}
......
On second I get empty object from internal record aggregation.
{
"trans_sum_b...": {
"trans": 389,
"auctions": 89,
"v": {}
}
},
{
"trans_sum_b...": {
"trans": 542,
"auctions": 30,
"v": {}
}
}
.....
I prefer json output and wasted couple hours to find out why I get empty 'v' field without success. So my question is "what the hell is going on" ;-) If my code is correct, what is wrong with the json output, that I don't see the results. If my code is wrong, why it's wrong and why table output results with what I need.
#user1875438 Your code is correct. It seems that there is bug in aql.
My result is the same as yours, the field of v is empty when using json mode.
I used tcpdump to grab the responses of aerospike-server when running these two commands, and found out the responses are the same, so I think it's very possible there is bug in aql tool.
159 0x0050: 0001 0000 0027 0113 0007 5355 4343 4553 .....'....SUCCES
160 0x0060: 5383 a603 7472 616e 7301 a903 6175 6374 S...trans...auct
161 0x0070: 696f 6e73 01a2 0376 81cd 07ce 01 ions...v.....
162 01:57:38.255065 IP localhost.hbci > localhost.57731: Flags [P.], seq 98:128, ack 144, win 42853, options [nop,nop,TS val 976630236 ecr 976630223], length 30
163 0x0000: 4500 0052 55f8 4000 4006 0000 7f00 0001 E..RU.#.#.......
I just posted an issue here.
The answer is simple as hell. But I'm new in Aerospike/Lua and I don't trust my knowledge so I searched for error everywhere but within AQL/UDF area. The problem is more fundamental and interferes with the specification of the JSON itself.
Keys in JSON have to be strings! So tostring(date['year']) solves problem.
Other question is does it is a bug or a feature :-) If Aerospike's map type allow integer keys should there be automatic key conversion from integer to string to satisfy JSON specification or not? IMHO there should be but probably some people disagree claiming that map type is not for integer keys...
I wrote a small script that creates Fibonacci sequence and returns a sum of all even integers.
function even_fibo()
-- create Fibonacci sequence
local fib = {1, 2} -- starting with 1, 2
for i=3, 10 do
fib[i] = fib[i-2] + fib[i-1]
end
-- calculate sum of even numbers
local fib_sum = 0
for _, v in ipairs(fib) do
if v%2 == 0 then
fib_sum = fib_sum + v
end
end
return fib_sum
end
fib = even_fibo()
print(fib)
The function creates the following sequence:
1, 2, 3, 5, 8, 13, 21, 34, 55
And returns the sum of its even numbers: 44
However, when I change the stop index from 10 to 100, in for i=3, 100 do the returned sum is negative -8573983172444283806 because the values become too big.
Why is my code working for 10 and not for 100?
Prior to version 5.3, Lua always stored numbers internally as floats. In 5.3 Lua numbers can be stored internally as integers or floats. One option is to run Lua 5.2, I think you'll find your code works as expected there. The other option is to initialize your array with floats which will promote all operations on them in the future to floats:
local fib = {1.0, 2.0}
Here is a hack written in hindsight.
The code exploits the mathematical fact that the even Fibonacci numbers are exactly those at indices that are multiple of 3.
This allows us to avoid testing the parity of very large numbers and provides high-order digits that are correct when you do the computation in floating-point. Then we redo it looking only at the low-order digits and combine the results. The output is 286573922006908542050, which agrees with WA. Values of d between 5 and 15 work fine.
a,b=0.0,1.0
s=0
d=10
for n=1,100/3 do
a,b=b,a+b
a,b=b,a+b
s=s+b
a,b=b,a+b
end
h=string.format("%.0f",s):sub(1,-d-1)
m=10^d
a,b=0,1
s=0
for n=1,100/3 do
a,b=b,(a+b)%m
a,b=b,(a+b)%m
s=(s+b)%m
a,b=b,(a+b)%m
end
s=string.format("%0"..d..".0f",s)
print(h..s)
I have been trying to produce a checksum based on a file header and am receiving conflicting results. In the slave devices manual, it states the following to produce the checksum:
"A simple eight-bit calculation is used for the header checksum. The steps required are as follows:
Calculate the sum of the header bytes in a single byte. Alternatively calculate
the sum and then AND the result with FFhex.
The checksum = FFhex - the sum from step 1."
Here, I have created the following code in Lua:
function header_checksum(string)
local sum = 0
for i = 1, #string do
sum = sum + string.byte(i)
end
local chksum = 255 - (sum & 255)
return chksum
end
If I send the following (4x byte) string down print(header_checksum("0181B81800")) I get the following result:
241 (string sent as you see it)
0 (each byte is changed to hex and then sent to function)
In the example given, it states that the byte should be AD, which is 173(dec) or \255.
Can someone please tell me what is wrong with what I am doing; either the code written, my approach, or both?
function header_checksum(header)
local sum = -1
for i = 1, #header do
sum = sum - header:byte(i)
end
return sum % 256
end
print(header_checksum(string.char(0x01,0x81,0xB8,0x18,0x00))) --> 173
I need a base converter function for Lua. I need to convert from base 10 to base 2,3,4,5,6,7,8,9,10,11...36 how can i to this?
In the string to number direction, the function tonumber() takes an optional second argument that specifies the base to use, which may range from 2 to 36 with the obvious meaning for digits in bases greater than 10.
In the number to string direction, this can be done slightly more efficiently than Nikolaus's answer by something like this:
local floor,insert = math.floor, table.insert
function basen(n,b)
n = floor(n)
if not b or b == 10 then return tostring(n) end
local digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
local t = {}
local sign = ""
if n < 0 then
sign = "-"
n = -n
end
repeat
local d = (n % b) + 1
n = floor(n / b)
insert(t, 1, digits:sub(d,d))
until n == 0
return sign .. table.concat(t,"")
end
This creates fewer garbage strings to collect by using table.concat() instead of repeated calls to the string concatenation operator ... Although it makes little practical difference for strings this small, this idiom should be learned because otherwise building a buffer in a loop with the concatenation operator will actually tend to O(n2) performance while table.concat() has been designed to do substantially better.
There is an unanswered question as to whether it is more efficient to push the digits on a stack in the table t with calls to table.insert(t,1,digit), or to append them to the end with t[#t+1]=digit, followed by a call to string.reverse() to put the digits in the right order. I'll leave the benchmarking to the student. Note that although the code I pasted here does run and appears to get correct answers, there may other opportunities to tune it further.
For example, the common case of base 10 is culled off and handled with the built in tostring() function. But similar culls can be done for bases 8 and 16 which have conversion specifiers for string.format() ("%o" and "%x", respectively).
Also, neither Nikolaus's solution nor mine handle non-integers particularly well. I emphasize that here by forcing the value n to an integer with math.floor() at the beginning.
Correctly converting a general floating point value to any base (even base 10) is fraught with subtleties, which I leave as an exercise to the reader.
you can use a loop to convert an integer into a string containting the required base. for bases below 10 use the following code, if you need a base larger than that you need to add a line that mapps the result of x % base to a character (usign an array for example)
x = 1234
r = ""
base = 8
while x > 0 do
r = "" .. (x % base ) .. r
x = math.floor(x / base)
end
print( r );