x87 FPU Programming Basics
Learn how to use the x87 Floating-Point Unit (FPU) for high-precision floating-point arithmetic in assembly language.
Meet the x87 FPU
The x87 Floating-Point Unit (FPU) is a specialized part of the CPU designed to handle mathematical operations on real numbers, also known as floating-point numbers.
Unlike integer arithmetic, floating-point math requires different internal representations and calculations, which the FPU excels at with high precision.
The FPU Register Stack
The x87 FPU uses a unique register stack, not general-purpose registers. This stack consists of eight 80-bit registers, denoted as ST(0) through ST(7).
ST(0)is always the top of the stack.- Operations push new values onto the stack or pop values from it, shifting existing values.
- It behaves like a Last-In, First-Out (LIFO) stack.