ia-32_volume1_basic-arch

Byte integers 128 bit packed word integers 128 bit

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Unformatted text preview: the names EAX, EBX, ECX, EDX, EBP, ESI, EDI, and ESP. EFLAGS register -- This 32-bit register (see Figure 3-8) is used to record the results of some compare operations. 11.2.1 SSE2 in 64-Bit Mode and Compatibility Mode In compatibility mode, SSE2 extensions function like they do in protected mode. In 64-bit mode, eight additional XMM registers are accessible. Registers XMM8-XMM15 are accessed by using REX prefixes. Memory operands are specified using the ModR/M, SIB encoding described in Section 3.7.5. Some SSE2 instructions may be used to operate on general-purpose registers. Use the REX.W prefix to access 64-bit general-purpose registers. Note that if a REX prefix is used when it has no meaning, the prefix is ignored. 11.2.2 Compatibility of SSE2 Extensions with SSE, MMX Technology and x87 FPU Programming Environment SSE2 extensions do not introduce any new state to the IA-32 execution environment beyond that of SSE. SSE2 extensions represent an enhancement of SSE extensions; they are fully compatible and share the same state information. SSE and SSE2 instructions can be executed together in the same instruction stream without the need to save state when switching between instruction sets. XMM registers are independent of the x87 FPU and MMX registers; so SSE and SSE2 operations performed on XMM registers can be performed in parallel with x87 FPU or MMX technology operations (see Section 11.6.7, "Interaction of SSE/SSE2 Instructions with x87 FPU and MMX Instructions"). The FXSAVE and FXRSTOR instructions save and restore the SSE and SSE2 states along with the x87 FPU and MMX states. 11-4 Vol. 1 PROGRAMMING WITH STREAMING SIMD EXTENSIONS 2 (SSE2) 11.2.3 Denormals-Are-Zeros Flag The denormals-are-zeros flag (bit 6 in the MXCSR register) was introduced into the IA-32 architecture with the SSE2 extensions. See Section 10.2.3.4, "Denormals-AreZeros," for a description of this flag. 11.3 SSE2 DATA TYPES SSE2 extensions introduced one 128-bit packed floating-point data type and four 128-bit SIMD integer data types to the IA-32 architecture (see Figure 11-2). Packed double-precision floating-point -- This 128-bit data type consists of two IEEE 64-bit double-precision floating-point values packed into a double quadword. (See Figure 4-3 for the layout of a 64-bit double-precision floatingpoint value; refer to Section 4.2.2, "Floating-Point Data Types," for a detailed description of double-precision floating-point values.) 128-bit packed integers -- The four 128-bit packed integer data types can contain 16 byte integers, 8 word integers, 4 doubleword integers, or 2 quadword integers. (Refer to Section 4.6.2, "128-Bit Packed SIMD Data Types," for a detailed description of the 128-bit packed integers.) 128-Bit Packed DoublePrecision Floating-Point 127 64 63 0 128-Bit Packed Byte Integers 127 0 128-Bit Packed Word Integers 127 0 128-Bit Packed Doubleword Integers 127 0 128-Bit Packed Quadword Integers 127 0 Figure 11-2....
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