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A function prologue typically does the following actions if the architecture has a base pointer (also known as frame pointer) and a stack pointer: Pushes current base pointer onto the stack, so it can be restored later. Value of base pointer is set to the address of stack pointer (which is pointed to the top of the stack) so that the base ...
x86 assembly language includes instructions for a stack-based floating-point unit (FPU). The FPU was an optional separate coprocessor for the 8086 through the 80386, it was an on-chip option for the 80486 series, and it is a standard feature in every Intel x86 CPU since the 80486, starting with the Pentium.
Below is the full 8086/8088 instruction set of Intel (81 instructions total). [2] These instructions are also available in 32-bit mode, in which they operate on 32-bit registers (eax, ebx, etc.) and values instead of their 16-bit (ax, bx, etc.) counterparts.
An autorelative pointer is a pointer whose value is interpreted as an offset from the address of the pointer itself; thus, if a data structure has an autorelative pointer member that points to some portion of the data structure itself, then the data structure may be relocated in memory without having to update the value of the auto relative ...
Pointer formats are known as near, far, or huge. Near pointers are 16-bit offsets within the reference segment, i.e. DS for data and CS for code. They are the fastest pointers, but are limited to point to 64 KB of memory (to the associated segment of the data type). Near pointers can be held in registers (typically SI and DI).
A computer program can access an address given explicitly – in low-level programming this is usually called an absolute address, or sometimes a specific address, and is known as pointer data type in higher-level languages. But a program can also use relative address which specifies a location in relation to somewhere else (the base address).
In the x86 assembly language, the JMP instruction performs an unconditional jump. Such an instruction transfers the flow of execution by changing the program counter.There are a number of different opcodes that perform a jump; depending on whether the processor is in real mode or protected mode, and an override instruction is used, the instructions may take 16-bit, 32-bit, or segment:offset ...
This article describes the calling conventions used when programming x86 architecture microprocessors. Calling conventions describe the interface of called code: The order in which atomic (scalar) parameters, or individual parts of a complex parameter, are allocated; How parameters are passed (pushed on the stack, placed in registers, or a mix ...