assembly - Intel x86 Opcode Reference? - Stack Overflow Hmm, interesting x86 has 8 registers, and a few opcodes use the low 3 bits to encode a destination register (including inc r32, dec r32, xchg r32, eax, and mov r32, imm32) This makes it natural to have groups of 3 bits in the encoding for other instructions, too –
Difference between: Opcode, byte code, mnemonics, machine code and . . . 68 is only one of the opcodes that x86 push can assemble to That's push imm32 There are other opcodes for push register (with the register number as part of the opcode byte), and for push imm8, and push r m (addressing via a modr m byte) –
x86 - How to read Assembly Opcode Reference? - Stack Overflow I want to make Assembly compiler To do that, I should make research about Assembly opcodes, so I found this on the Web When I test to compile some codes with NASM, like this: add eax, eax It out
How to read the Intel Opcode notation - Stack Overflow Many opcodes for immediate versions of instructions, including 83, use the 3-bit r field in the ModR M byte as 3 extra opcode bits Intel's vol 2 manual documents this, and the opcode table in an appendix includes it, I think
where can I find a description of *all* MIPS instructions Does anyone know of a web site where I can find a list of 32-bit MIPS instructions opcodes, with the following features: Clearly distinguishes between real opcodes and assembly-language macros (pseudo-instructions) Describes the instruction behavior including differences depending on privilege level
What is the difference between Mnemonics and Opcode (the B8 to BF opcodes are all mov-immediate to register, each with a different destination reg ) 32bit x86 has single-byte opcodes for inc dec of registers x86-64 repurposed that contiguous range of 16 opcodes for use as REX prefix bytes (leaving the two-byte inc r m32 form as the only option for inc eax )
How to get opcodes of PHP? - Stack Overflow The Vulcan Logic Disassembler hooks into the Zend Engine and dumps all the opcodes (execution units) of a script It was written as as a beginning of an encoder, but I never got the time for that It can be used to see what is going on in the Zend Engine Once installed, you can use it like this:
assembly - x86 XOR opcode differences - Stack Overflow Bit #0 of those opcodes is sometimes called the "size" bit These "basic ALU" instructions that have an encoding for each direction and size combo date back to original 8086; many later instructions like 386 bsf r, r m or 186 imul r, r m, imm don't have a form that could allow a memory destination Or for bt* r m, r only the destination can be