Intel’s vol.2 manual has details on the encoding of operands for each form of each instruction. E.g. taking just the 8-bit operand size versions of the well-known add instruction, which has 2 reg,rm forms ; a rm,immediate form ; and a no-ModRM 2-byte short form for add al, imm8 Opcode Instruction | Op/En | 64-bit … Read more
The code must be in a page with execute permission. By default, stack and read-write static data (like non-const globals) are in pages mapped without exec permission, for security reasons. The simplest way is to compile with gcc -z execstack, which links your program such that stack and global variables (static storage) get mapped in … Read more
My guess is that the point is to copy the values into local variables once, to avoid having to fetch the field value repeatedly from the heap for each iteration of the loop in the next few lines. Of course, that begs the question as to why the same comment hasn’t been applied on the … Read more
\ (backslash) is the namespace separator in PHP 5.3. A \ before the beginning of a function represents the Global Namespace. Putting it there will ensure that the function called is from the global namespace, even if there is a function by the same name in the current namespace.