The second version of my first try to make music with my new USB MIDI adapter.
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I’ve been very busy lately. The good news is that I have tons of painting to upload. But at the moment writing is not my first priority. However, I read weblogs of web development celebrities almost on a daily basis.
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Here is a little function that uses Lua File System (lfs module) in order to traverse all the files in a folder and its sub folders (and their sub folders) recursively.
DIR_SEP="\\" --should be "/" for Unix platforms (Linux and Mac)
function browseFolder(root)
for entity in lfs.dir(root) do
if entity~="." and entity~=".." then
local fullPath=root..DIR_SEP..entity
--print("root: "..root..", entity: "..entity..", mode: "..(lfs.attributes(fullPath,"mode")or "-")..", full path: "..fullPath)
local mode=lfs.attributes(fullPath,"mode")
if mode=="file" then
--this is where the processing happens. I print the name of the file and its path but it can be any code
print(root.." > "..entity)
elseif mode=="directory" then
browseFolder(fullPath);
end
end
end
end
--this is a sample call
browseFolder(".")
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Here is a little function that I developed to test if a string is a valid IPv4 address (that is 4 numbers between 0 to 255 separated with “.”)
---checks if a string represents an ip address
-- @return true or false
function isIpAddress(ip)
if not ip then return false end
local a,b,c,d=ip:match("^(%d%d?%d?)%.(%d%d?%d?)%.(%d%d?%d?)%.(%d%d?%d?)$")
a=tonumber(a)
b=tonumber(b)
c=tonumber(c)
d=tonumber(d)
if not a or not b or not c or not d then return false end
if a<0 or 255<a then return false end
if b<0 or 255<b then return false end
if c<0 or 255<c then return false end
if d<0 or 255<d then return false end
return true
end
And here are some tests:
assert(isIpAddress("1.1.1.1")==true)
assert(isIpAddress("255.1.1.1")==true)
assert(isIpAddress("255.255.0.0")==true)
assert(isIpAddress("0.0.0.0")==true)
assert(isIpAddress("255.255.255.255")==true)
assert(isIpAddress("0.0.0.1")==true)
assert(isIpAddress("0.0.1.1")==true)
assert(isIpAddress("0.1.1.1")==true)
assert(isIpAddress("1.2.3.4")==true)
assert(isIpAddress(nil)==false)
assert(isIpAddress("")==false)
assert(isIpAddress("1")==false)
assert(isIpAddress("1.2")==false)
assert(isIpAddress("1.2.3")==false)
assert(isIpAddress("1.2.3.4.")==false)
assert(isIpAddress(".1.2.3.4")==false)
assert(isIpAddress("0")==false)
assert(isIpAddress("-1")==false)
assert(isIpAddress("256")==false)
assert(isIpAddress("-1.2.3.4")==false)
assert(isIpAddress("1.-2.3.4")==false)
assert(isIpAddress("1.2.-3.4")==false)
assert(isIpAddress("1.2.3.-4")==false)
assert(isIpAddress("256.2.3.4")==false)
assert(isIpAddress("1.256.3.4")==false)
assert(isIpAddress("1.2.256.4")==false)
assert(isIpAddress("1.2.3.256")==false)
assert(isIpAddress("256.256.256.256")==false)
assert(isIpAddress("1000.0.0.0")==false)
assert(isIpAddress("a.b.c.d")==false)
assert(isIpAddress("a.2.c.d")==false)
assert(isIpAddress("a.b.3.d")==false)
assert(isIpAddress("a.b.c.4")==false)
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Here are all the valid subnet masks for IPv4:
The following Lua script was used to calculate those values:
map={
["00000000"]="0",
["10000000"]="128",
["11000000"]="192",
["11100000"]="224",
["11110000"]="240",
["11111000"]="248",
["11111100"]="252",
["11111110"]="254",
["11111111"]="255"
}
for i=1,31 do
s=string.rep("1",i)..string.rep("0",32-i)
print(map[s:sub( 1, 8)].."."..map[s:sub( 9,16)].."."..map[s:sub(17,24)].."."..map[s:sub(25,32)])
end
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Apparently back side of the paper I have is much better than its front side!
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I needed to connect my Tele2 usb modem to Ubuntu and here is a good solution.
It’s basically these lines that made it work:
$ cd /etc/usb_modeswitch.d $ sudo tar xzf /usr/share/usb_modeswitch/configPack.tar.gz 12d1:1446 $ sudo sed -i -e 's/14ac"/14ac,1506"/' 12d1\:1446
Also it seems that the following command is required for it to work:
$ sudo modprobe usbserial vendor=0x12d1 product=0x1506
After that, you need to configure Ubuntu Network Connections (the little network icon on the top right of the screen near the speaker icon). Go to “Mobile Broadband” tab, click “Add”. Select “Sweden” as your country, “Tele2″ as your operator and “Mobile Bredband” as your data plan.
Then use the following configurations:
PS. The Linux version of the driver is really stable! I share the Internet using an Asus Eee Box and an access point to 4 other wireless devices at home. In Windows, the device used to get disconnected and sometimes it had to be removed from the USB port and inserted again (even when using the latest driver from Huawei). In Linux this hasn’t happened during the last week.
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I don’t know how fast this was going but I am could feel the pressure in my ears when I used this elevator.
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