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Intel 253666-024US User Manual

Page 52

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3-6 Vol. 2A

INSTRUCTION SET REFERENCE, A-M

Sreg — A segment register. The segment register bit assignments are ES = 0,
CS = 1, SS = 2, DS = 3, FS = 4, and GS = 5.

m32fp, m64fp, m80fp — A single-precision, double-precision, and double
extended-precision (respectively) floating-point operand in memory. These
symbols designate floating-point values that are used as operands for x87 FPU
floating-point instructions.

m16int, m32int, m64int — A word, doubleword, and quadword integer
(respectively) operand in memory. These symbols designate integers that are
used as operands for x87 FPU integer instructions.

ST or ST(0) — The top element of the FPU register stack.

ST(i) — The i

th

element from the top of the FPU register stack (i ← 0 through 7).

mm — An MMX register. The 64-bit MMX registers are: MM0 through MM7.

mm/m32 — The low order 32 bits of an MMX register or a 32-bit memory
operand. The 64-bit MMX registers are: MM0 through MM7. The contents of
memory are found at the address provided by the effective address computation.

mm/m64 — An MMX register or a 64-bit memory operand. The 64-bit MMX
registers are: MM0 through MM7. The contents of memory are found at the
address provided by the effective address computation.

xmm — An XMM register. The 128-bit XMM registers are: XMM0 through XMM7;
XMM8 through XMM15 are available using REX.R in 64-bit mode.

xmm/m32— An XMM register or a 32-bit memory operand. The 128-bit XMM
registers are XMM0 through XMM7; XMM8 through XMM15 are available using
REX.R in 64-bit mode. The contents of memory are found at the address provided
by the effective address computation.

xmm/m64 — An XMM register or a 64-bit memory operand. The 128-bit SIMD
floating-point registers are XMM0 through XMM7; XMM8 through XMM15 are
available using REX.R in 64-bit mode. The contents of memory are found at the
address provided by the effective address computation.

xmm/m128 — An XMM register or a 128-bit memory operand. The 128-bit XMM
registers are XMM0 through XMM7; XMM8 through XMM15 are available using
REX.R in 64-bit mode. The contents of memory are found at the address provided
by the effective address computation.

3.1.1.3

64-bit Mode Column in the Instruction Summary Table

The “64-bit Mode” column indicates whether the opcode sequence is supported in
64-bit mode. The column uses the following notation:

Valid — Supported.

Invalid — Not supported.

N.E. — Indicates an instruction syntax is not encodable in 64-bit mode (it may
represent part of a sequence of valid instructions in other modes).