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I am writing a adler32 code to compute the adler32 checksum of a string.
On the net I came across various sample codes:
I did not understand some code entirely as <b>it has additional code</b> marked in bold below apart from the basic implementation of the adler32 logic.
I did not understand the addional part as to what is is doing.
Can anybody experienced with adler32 give some hint on it?
The various sample codes are:
//---------------------------------------------------------------------
// WIKI
I understood this code as its the basic implementation of the adler32 logic.
So no doubts in this.
/* Loop over each byte of data, in order */
for (size_t index = 0; index < blen; ++index)
{
a = (a + buff[index]) % BASE;
b = (b + a) % BASE;
}
wweak_cs = (b << 16) | a;
//---------------------------------------------------------------------
// RSYNC
I did not understand some code marked in bold below.
{
#define CHAR_OFFSET 0
char *buf = buff;
int len = blen;
int index = 0;
UINT32 s1, s2;
s1 = s2 = 0;
for (index = 0; index < (len-4); index+=4)
{
s2 += 4*(s1 + buf[index]) + 3*buf[index+1] + 2*buf[index+2] + buf[index+3] + 10*CHAR_OFFSET;
s1 += (buf[index+0] + buf[index+1] + buf[index+2] + buf[index+3] + 4*CHAR_OFFSET);
}
for (; index < len; index++)
{
s1 += (buf[index]+CHAR_OFFSET); s2 += s1;
}
rweak_cs = (s1 & 0xffff) + (s2 << 16);
weak_cs = rweak_cs;
}
//---------------------------------------------------------------------
// sharpdevelop
I did not understand some code marked in bold below.
{
char *buf = buff;
int len = blen;
sweak_cs = 1;
int s1 = sweak_cs & 0xFFFF;
int s2 = sweak_cs >> 16 & 0xFFFF;
int index =0;
while (len > 0)
{
int n = 3800;
if (n > len)
{
n = len;
}
len -= n;
while (--n >= 0)
{
s1 = s1 + (int)(buf[index++] & 0xFF);
s2 = s2 + s1;
}
s1 %= BASE;
s2 %= BASE;
}
sweak_cs = (s2 << 16) | s1;
weak_cs = sweak_cs;
}
//---------------------------------------------------------------------
//altivec
I did not understand some code marked in bold below.
{
#define NMAX 5552 /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
#define DO1(buf,i) {s1 += buf[i]; s2 += s1;}
#define DO2(buf,i) DO1(buf,i); DO1(buf,i+1);
#define DO4(buf,i) DO2(buf,i); DO2(buf,i+2);
#define DO8(buf,i) DO4(buf,i); DO4(buf,i+4);
#define DO16(buf) DO8(buf,0); DO8(buf,8);
# define MOD(a) a %= BASE
char *buf = buff;
int len = blen;
aweak_cs = 1;
unsigned long s1 = aweak_cs & 0xffff;
unsigned long s2 = (aweak_cs >> 16) & 0xffff;
int k;
while (len > 0)
{
k = len < NMAX ? (int)len : NMAX;
len -= k;
while (k >= 16)
{
DO16(buf);
buf += 16;
k -= 16;
}
if (k != 0)
{
do
{
s1 += *buf++;
s2 += s1;
} while (--k);
}
MOD(s1);
MOD(s2);
}
aweak_cs = (s2 << 16) | s1;
weak_cs = aweak_cs;
}
Can anybody clear the doubts?
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Why do you need the 'additional code' can you just use the basic algorithm?
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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Here also Mr Palini is gracing the posts by his immmaculate understanding of software. Trying to highlack things. Boss come on earth else you will thump down.
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tom groezer wrote: Here also Mr Palini is gracing the posts by his immmaculate understanding of software.
Wow, that's actually nice!
Well, of course you missed the point of my post.
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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I posted this in the XML forum but now this is definitely a code question.
In the following code using wxWidgets I am trying to access a file inside a zip archive. As you see I have the archiveURL variable set and pass that OpenFile() method.
[code]
wxString archiveURL = _("file:/C:/RM-XML.zip#zip:RM-XML/Attacks.xml");
wxFileSystem* fileSystem = new wxFileSystem;
wxFSFile* file = fileSystem->OpenFile(archiveURL);
if (file)
{
wxInputStream* stream = file->GetStream();
wxXmlDocument xmlFile;
xmlFile.Load(*stream);
if(xmlFile.IsOk())
wxMessageBox(_("Did open xml File"));
else
wxMessageBox(_("Did Not open xml File"));
}
[/code]
The issue is with the variable file. It's corrupted or something because the if(file) comes back false and if I try to access it file->GetLocation() I get a delayed crash after about 7 seconds. I'm pretty sure the zip file is okay and I can use Windows explorer to get the file if I copy and paste the archiveURL string (without the #zip: into the search bar. So I'm stumped. Not sure how to proceed in fixing the variable file. Any ideas?
Thanks!
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I notice wxFileSystem has a URLToFileName method - have you tried converting your URL to a filesystem path and opening that rather than the URL? Obviously, the file is NOT opening, as if (file) fails, so (again, obviously) no operations on file can be performed.
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
CodeProject MVP for 2010 - who'd'a thunk it!
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fixed!
the solution lies in the file path
"file:/C:/RM-XML.zip#zip:RM-XML/Attacks.xml" is not correct
"file:C:/RM-XML.zip#zip:RM-XML/Attacks.xml" is correct
Thanks for pointing out the obvious. It worked. 
Also adding this line even those I have something similar in the OnInit() under the App class
fileSystem->AddHandler(new wxZipFSHandler);
is a necessary line. Without, it doesn't work. Weird.
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hi,
i have localize my multibyte application.Everything is working fine except tooltips and msflexgrid headers which are showing garbage.is there any trick that i can show them in japanese with keeping project multibyte.
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instead of saking again you should use Unicode. I got no further clue. Or write your own tooltips as i wrote you a time ago. 
Press F1 for help or google it.
Greetings from Germany
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actually i think msflexgrid dnt support unicode.so is there anyway to make it support unicode?
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Why do you think so ?
virtual void BeHappy() = 0;
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bcoz other resources showing japanese but only toolbar tooltips and msflexgrid headers are showing japanese. So they are not supportive for unicode.
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Maybe, the headers do hold its titles in TCHAR*,
that is only char* in a MULTIBYTE-app (no wide character support)
and WCHAR* in a UNICODE-app (wide character supported)
virtual void BeHappy() = 0;
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i found that ms hierarichal data grid is unicode so now my qus is that can it be used to display tabular data like in msflexgrid?
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Hi,
I have a .vbs script to compile c project. When I try to run it under command prompt it display a message "This script must run under CScript".
I tried to search script on Google but can not find.
Please help....
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Try MSDN, I found the answer here[^].
txtspeak is the realm of 9 year old children, not developers. Christian Graus
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john5632 wrote: I have a .vbs script to compile c project.
Not really a C/C++/MFC question, but I'll play along.
john5632 wrote: When I try to run it under command prompt...
How exactly?
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"Man who follows car will be exhausted." - Confucius
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Hello Friends
I am having dll that I created using Visual Studio 2008 for WindowsXP(32 bit).Now I tried that dll on windows7 and on windows Vista and its running,but I want to take advantage of their 64 bit windows.
So,I want to know that how can I migrate my dll to take advantage of 64bit windows.Do I need to install any other compiler with VS2008 ?Or do i need to change in coding too?
Thanks & Regards
Yogesh
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Thanks,But I want to know that Can I install 64 bit compiler on a machine having 32 bit compiler with 32bit specific hardware?
And to install 64 bit compiler on 64 bit machine,do i need to install vs2008 from starting or can I set after installing it also?
Thanks For your valuable answer.
Regards
Yogesh
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You can install the 64-bit compiler on 32-bit Windows and 32-bit hardware.
You can also build 64-bit executables on these machines.
But you will not be able to run it.
If you have done a previous Visual Studio install, you can modify it to add the 64-bit compiler rather than reinstalling the entire package.
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Hello
I installed 64 bit compiler but after that what I have to do to migrate 32 bit code to run on 64 bit operating System?
Yogesh
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The dll must always be the same bits as the executable. If the executable is 32-bit then making the dll 64-bit is pointless, as it won't even load.
There is sufficient light for those who desire to see, and there is sufficient darkness for those of a contrary disposition.
Blaise Pascal
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Ok,that Concept I understand.If executable is of 64 bit then its all libraries should be of 64 bit.And If those library also have some dependent library or dll that should also be 64 bit. Is it?
Thanks for your Help.
Regards
Yogesh
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