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existing instructions extended to a 64 bit address size (JRCXZ) existing instructions extended to a 64 bit operand size (remaining instructions) Most instructions with a 64 bit operand size encode this using a REX.W prefix; in the absence of the REX.W prefix, the corresponding instruction with 32 bit operand size is encoded. This mechanism also ...
AMD64 (also variously referred to by AMD in their literature and documentation as “AMD 64-bit Technology” and “AMD x86-64 Architecture”) was created as an alternative to the radically different IA-64 architecture designed by Intel and Hewlett-Packard, which was backward-incompatible with IA-32, the 32-bit version of the x86 architecture.
While what these instructions do is similar to bit level gather-scatter SIMD instructions, PDEP and PEXT instructions (like the rest of the BMI instruction sets) operate on general-purpose registers. [12] The instructions are available in 32-bit and 64-bit versions. An example using arbitrary source and selector in 32-bit mode is:
The PUSHF and POPF instructions transfer the 16-bit FLAGS register. PUSHFD/POPFD (introduced with the i386 architecture) transfer the 32-bit double register EFLAGS. PUSHFQ/POPFQ (introduced with the x86-64 architecture) transfer the 64-bit quadword register RFLAGS. In 64-bit mode, PUSHF/POPF and PUSHFQ/POPFQ are available but PUSHFD/POPFD are not.
In computer programming, assembly language (alternatively assembler language [1] or symbolic machine code), [2] [3] [4] often referred to simply as assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence between the instructions in the language and the architecture's machine code instructions. [5]
Microsoft Macro Assembler (MASM) is an x86 assembler that uses the Intel syntax for MS-DOS and Microsoft Windows.Beginning with MASM 8.0, there are two versions of the assembler: One for 16-bit & 32-bit assembly sources, and another (ML64) for 64-bit sources only.
AMD's 64-bit extension to the original instruction set make relatively few changes to 32-bit addressing, with the most significant being that in long mode, 64-bit addressing is the default. 64-bit registers (RAX, RBX, RCX, etc.) are used rather than 32-bit registers for address computation.
An instruction set architecture (ISA) is an abstract model of a computer, also referred to as computer architecture.A realization of an ISA is called an implementation.An ISA permits multiple implementations that may vary in performance, physical size, and monetary cost (among other things); because the ISA serves as the interface between software and hardware.