opcode | 易学教程

Can we construct an instance of `OpCode`?

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问题 The .NET Framework 4.0 introduces several items to the Reflection API that range from extremely useful to vital for my work. Among these are protected constructors for Assembly , Module , MethodBody , and LocalVariableInfo and the new CustomAttributeData class. There are a couple items I still need that are quite troublesome to work around. I believe they easily apply to the same [small] group of people would need to extend the types I just listed. This time : I'm looking for a way to

Why call instruction opcode is represented as FF15?

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问题 I am still learning assembly and trying to connect an instruction with it's opcode. Reading pdf at https://code.google.com/p/corkami/wiki/PE101?show=content It just dissect a PE file of a simple program that show message box in windows, the code is "removing all unrelated entries" push 0 push Title + DATADELTA push Caption + DATADELTA push 0 call [__imp__MessageBoxA] When trying to look at the generated exe file ".text" section, the last call is represent with opcode "FF15" checking Intel

Why does the ia32/x64 opcode map document 0x66 and 0xF2 as a double mandatory prefix for opcode 0x0F38F1 (CRC32)?

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问题 In the Intel 64 and IA-32 Architectures Software Developer's Manual, Row F table A-4 Appendix A.3 Volume 2C (Order Number 326018-045US January 2013) is unique in that it has a prefix sub-row for a combination of two prefixes: 0x66 and 0xF2. The only opcode for which this is relevant is 0x0F38F1 (CRC32). For the prefix 0xF2 alone, the source operand is Ey (memory or general purpose register; 32 bit or 64 bit), and for the prefixes 0x66 and 0xF2 together, the source operand is Ew (memory or

Python doesn't have opcode cacher?

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问题 I'm currently using PHP. I plan to start using Django for some of my next project. But I don't have any experience with Python. After some searching, I still can't find a Python opcode cacher. (There are lots of opcode cacher for PHP: APC, eAccelerator, Xcache, ...) 回答1: It's automatic in Python -- a compiled .pyc file will appear magically. 回答2: Python doesn't need one the same way PHP needs it. Python doesn't throw the bytecode away after execution, it keeps it around (as .pyc files). 回答3:

What is the purpose of the 40h REX opcode in ASM x64?

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问题 I've been trying to understand the purpose of the 0x40 REX opcode for ASM x64 instructions. Like for instance, in this function prologue from Kernel32.dll: As you see they use push rbx as: 40 53 push rbx But using just the 53h opcode (without the prefix) also produces the same result: According to this site, the layout for the REX prefix is as follows: So 40h opcode seems to be not doing anything. Can someone explain its purpose? 回答1: the 04xh bytes (i.e. 040h , 041h ... 04fh ) are indeed REX

Status of JSR/RET in JVM spec

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问题 There are some parts of the JVM specification which suggest that the operations JSR (Jump SubRoutine), JSR_W (Jump SubRoutine Wide) and RET (RETurn from subroutine) may be used only up to class file version 50.0 (JDK 1.6): 3.13 Compiling Finally (This section assumes a compiler generates class files with version number 50.0 or below, so that the jsr instruction may be used. See also §4.10.2.5.) And later: 4.10.2.5. Exceptions and finally To implement the try - finally construct, a compiler

Unhandled dwarf expression

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问题 Can anybody tell me what exactly the following segmentation fault means? Unhandled dwarf expression opcode 0x93 Its on solaris 10 i386. Any advice appreciated. 回答1: This sort of error message ("unhandled dwarf expression") can occur if your version of GDB is too old (older than the compiler that generated the code). Try installing the latest version of gdb and running that. 回答2: This may not immediately help, but "dwarf" probably refers to the DWARF Debugging Standard. The wikipedia entry for

Decoding and matching Chip 8 opcodes in C/C++

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问题 I'm writing a Chip 8 emulator as an introduction to emulation and I'm kind of lost. Basically, I've read a Chip 8 ROM and stored it in a char array in memory. Then, following a guide, I use the following code to retrieve the opcode at the current program counter (pc): // Fetch opcode opcode = memory[pc] << 8 | memory[pc + 1]; Chip 8 opcodes are 2 bytes each. This is code from a guide which I vaguely understand as adding 8 extra bit spaces to memory[pc] (using << 8) and then merging memory[pc

How to compile PHP into opcode and run it in production environment?

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问题 Note,it's not what the recent hiphop project of facebook,I just want to convert it into opcode ,not c/c++ . Is there a solution yet? A demo is always the best! 回答1: What you're looking for is a PHP Accelerator However, these tools compile to bytecode, not opcode as requested. 回答2: @Dolph's answer is correct: There's no way to compile PHP directly to opcode . The PHP binary itself compiles PHP code to PHP bytecode and then executes those bytecodes. The best you can expect it to cache the

Decoding and matching Chip 8 opcodes in C/C++

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I'm writing a Chip 8 emulator as an introduction to emulation and I'm kind of lost. Basically, I've read a Chip 8 ROM and stored it in a char array in memory. Then, following a guide, I use the following code to retrieve the opcode at the current program counter (pc): // Fetch opcode opcode = memory[pc] << 8 | memory[pc + 1]; Chip 8 opcodes are 2 bytes each. This is code from a guide which I vaguely understand as adding 8 extra bit spaces to memory[pc] (using << 8) and then merging memory[pc + 1] with it (using |) and storing the result in the opcode variable. Now that I have the opcode