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The x86 extended-precision format is an 80-bit format first implemented in the Intel 8087 math coprocessor and is supported by all processors that are based on the x86 design that incorporate a floating-point unit (FPU). The Intel 8087 was the first x86 device which supported floating-point arithmetic in hardware. It was designed to support a ...
Real floating-point type, usually mapped to an extended precision floating-point number format. Actual properties unspecified. Actual properties unspecified. It can be either x86 extended-precision floating-point format (80 bits, but typically 96 bits or 128 bits in memory with padding bytes ), the non-IEEE " double-double " (128 bits), IEEE ...
The former loads a 80-bit BCD integer into the FPU, while the latter writes a FPU value as a 80-bit integer value into the memory. Inside of the FPU, the values are stored as normal x87 extended-precision floats. Unlike the integer-facing versions, the two instructions remain available in long mode. [1] The 80-bit format is divided into the ...
An exception is Microsoft Visual C++ for x86, which makes long double a synonym for double. [2] The Intel C++ compiler on Microsoft Windows supports extended precision, but requires the /Qlong‑double switch for long double to correspond to the hardware's extended precision format. [3]
Each x87 register, known as ST(0) through ST(7), is 80 bits wide and stores numbers in the IEEE floating-point standard double extended precision format. These registers are organized as a stack with ST(0) as the top.
The x86 instruction set refers to the set of instructions that x86-compatible microprocessors support. The instructions are usually part of an executable program, often stored as a computer file and executed on the processor. The x86 instruction set has been extended several times, introducing wider registers and datatypes as well as new ...
On x86 and x86-64, the most common C/C++ compilers implement long double as either 80-bit extended precision (e.g. the GNU C Compiler gcc [13] and the Intel C++ Compiler with a /Qlong‑double switch [14]) or simply as being synonymous with double precision (e.g. Microsoft Visual C++ [15]), rather than as quadruple precision.
The standard provides for many closely related formats, differing in only a few details. Five of these formats are called basic formats, and others are termed extended precision formats and extendable precision format. Three formats are especially widely used in computer hardware and languages: [citation needed]