crc32

问题 I do check sum of classes.dex in native code as indicated here: Check .apk-signature in C/native Code Calculate checksum of classes.dex compare with hardcoded value - xxx if it's true, pass and go on if it's not true, exit the app What I do is log the checksum value for the first build, then change the if (checksum == xxx) in native code to be the same as the logged value. However, with using Dexguard, the checksum is different for every different build, means that if I change xxx, and

问题 I want my Greasemonkey script to run ONLY when the static page it's accessing has the exact same content as before... Now I have the ability to set a variable containing a hash of this page. I'm looking for a way to hash the page on the fly, so that I can compare my hash to the generated hash... Any ideas on how to accomplish this, on the fly, hashing? 回答1: From your question: I want my Greasemonkey script to run ONLY when the static page it's accessing has the exact same content as before...

问题 I'm trying to calculate the Frame Check Sequence (FCS) of an Ethernet packet byte by byte. The polynomial is 0x104C11DB7 . I did follow the XOR-SHIFT algorithm seen here http://en.wikipedia.org/wiki/Cyclic_redundancy_check or here http://www.woodmann.com/fravia/crctut1.htm Assume the information that is supposed have a CRC is only one byte. Let's say it is 0x03. step: pad with 32 bits to the right 0x0300000000 align the polynomial and the data at the left hand side with their first bit that

问题 I use java.util.zip.CRC32 which I understand implements CRC32 (and not CRC32b), but it seems like I need to use CRC32b instead of CRC32. is there a Java open source code I can use for CRC32b calculation? 回答1: CRC32b is a coined term if I remember correctly, equal to CRC32 with the 4 bytes reversed. int crc32b(int crc) { ByteBuffer buf = ByteBuffer.allocate(4); buf.putInt(crc); // BIG_ENDIAN by default. buf.order(ByteOrder.LITTLE_ENDIAN); return buf.getInt(0); } For instance for input '1':

问题 I am currently trying to implement a CRC-32 for an incoming datastream (Serial communication) on an ATMEGA1280 and I am a little lost how to do this on the embedded side in C.... If anyone could point me in the proper direction and/or help in anyway i would greatly appreciate it... 回答1: You should know what polynomial you are dealing with. So it is not enough to know that you are using CRC, but you should also know polynomial. You are looking for function with this kind of prototype uint32_t

问题 I have question about BCH Encoding. Is BCH Encoding is the same operation like CRC remainder calculation? M(x) mod G(x) = R(x) and R(x) is my BCH code? 回答1: You are pretty much correct. To be precise, if your generator polynomial is g(x) and your block size is n , then the valid code words are the multiples of g(x) with degree < n . Lets say you have a message m(x) of degree < k , and g(x) has degree n-k : There are different ways you could turn your message into a unique valid code word. m(x

问题 I have the following function: byte[] test1 = {1,2,3,4}; byte[] test2 = {5,6,7,8}; ByteBuffer bbtest1 = ByteBuffer.wrap(test1).order(ByteOrder.LITTLE_ENDIAN); ByteBuffer bbtest2= ByteBuffer.wrap(test2).order(ByteOrder.LITTLE_ENDIAN); ByteBuffer contents = ByteBuffer.allocate(bbtest1.limit() + bbtest2.limit()); contents.put(bbtest1); contents.put(bbtest2); CRC32 checksum = new CRC32(); checksum.update(contents); System.out.println(checksum.getValue()); No matter what values I assign my byte

问题 I'm calculating CRC32 like code below : import java.util.zip.CRC32; String data = "99D5503012013165411"; byte bytes[] = data.getBytes(); Checksum checksum = new CRC32(); checksum.update(bytes, 0, bytes.length); long checksumValue = checksum.getValue(); System.out.println("Result of CRC32 : " +Long.toHexString(checksumValue) + " !"); when I compare my code with this online CRC32 calculation it only gives me the right result when the Input type ASCII, So there is a way to have the same result

问题 I'm new to swift/xcode and am trying to use the crc32 function that, as mentioned here, is provided in zlib from libz.dylib . I've modified the code so that I am now trying: let message1 = "some message".first?.value!.data(using: String.Encoding.utf8, allowLossyConversion: false) let crc = crc32(CLong(0), UnsafePointer<Bytef>(strcat!.bytes), UInt(message1!.length)) however I am encountering the error: use of unresolved identifier 'crc32' . Could anyone help me to figure out what step I might

问题 I've done quite a bit of checking up on other questions and I'm still uncertain on the issue. Here's my usage case: I have an online shopping cart. Occassionaly, certain clients find the ordering process either too tedious, or there are some clients where an online order will not cut it, and they need an actual PDF estimate (quote) in order to purchase a product. So I coded in a module that takes the shopping cart contents, and lays out neatly as a PDF estimate. Now because this process only