I think everyone is giving you the same answer. Instruction set is is the set (as in math) of all instructions the processor can execute or understand. Assembly language is a programming language. Let me try some examples based on some of the questions you are asking. And I am going to be jumping around … Read more
Rotates are required for bit shifts across multiple words. When you SHL the lower word, the high-order bit spills out into the carry. To complete the operation, you need to shift the higher word(s) while bringing in the carry to the low-order bit. RCL is the instruction that accomplishes this. High word Low word CF … Read more
Assembly language is a convenience mechanism over the machine language. With assembly language you use mnemonic sequences instead of numeric operation codes and can use symbolic labels instead of manually calculating offsets. It also protects you from really dumb errors – like typing a malformed processor instruction. Otherwise the assembly language is the equivalent of … Read more
The ARM world is a bit messy. For the C programmers, things are simple: all ARM architectures offer a regular, 32-bit with flat addressing programming model. As long as you stay with C source code, the only difference you may see is about endianness and performance. Most ARM processors (even old models) can be both … Read more
It is a NOP. The following are typcially used as NOP. They all do the same thing but they result in machine code of different length. Depending on the alignment requirement one of them is chosen: xchg eax, eax = 90 mov eax, eax = 89 C0 lea eax, [eax + 0x00] = 8D 40 … Read more
Yes they do. AMD even provides the specification up to the HD4000 series at the moment. Take a look here at AMD’s R700 instruction set reference guide. There is also an open source project called Nouveau that does reverse engineering of the Nvidia instruction sets. Note that Nvidia has a slightly different architecture than AMD … Read more
The unix.linux file command is great for this. It can generally detect the target architecture and operating system for a given binary (and has been maintained on and off since 1973. wow!) Of course, if you’re not running under unix/linux – you’re a bit stuck. I’m currently trying to find a java based port that … Read more
The ARM processor has 2 instruction sets, the traditional ARM set, where the instructions are all 32-bit long, and the more condensed Thumb set, where most common instructions are 16-bit long (and some are 32-bit long). Which instruction set to run can be chosen by the developer, and only one set can be active (i.e. … Read more
I’ve created a GitHub repro that will detect CPU and OS support for all the major x86 ISA extensions: https://github.com/Mysticial/FeatureDetector Here’s a shorter version: First you need to access the CPUID instruction: #ifdef _WIN32 // Windows #define cpuid(info, x) __cpuidex(info, x, 0) #else // GCC Intrinsics #include <cpuid.h> void cpuid(int info[4], int InfoType){ __cpuid_count(InfoType, 0, … Read more