RSQRTPS

Compute Reciprocals of Square Roots of Packed Single-Precision Floating-Point Values

Opcodes

Hex Mnemonic Encoding Long Mode Legacy Mode Description
0F 52 /r RSQRTPS xmm1, xmm2/m128 A Valid Valid Computes the approximate reciprocals of the square roots of the packed single-precision floating-point values in xmm2/m128 and stores the results in xmm1.

Instruction Operand Encoding

Op/En Operand 0 Operand 1 Operand 2 Operand 3
A NA NA ModRM:r/m (r) ModRM:reg (w)

Description

Performs a SIMD computation of the approximate reciprocals of the square roots of the four packed single-precision floating-point values in the source operand (second operand) and stores the packed single-precision floating-point results in the destination operand. The source operand can be an XMM register or a 128-bit memory location. The destination operand is an XMM register. See Figure 10-5 in the Intel® 64and IA-32 Architectures Software Developer's Manual, Volume 1, for an illustration of a SIMD single-precision floating-point operation.

The relative error for this approximation is:

|Relative Error| &le 1.5 * 2-12

The RSQRTPS instruction is not affected by the rounding control bits in the MXCSR register. When a source value is a 0.0, an ∞ of the sign of the source value is returned. A denormal source value is treated as a 0.0 (of the same sign). When a source value is a negative value (other than -0.0), a floating-point indefinite is returned. When a source value is an SNaN or QNaN, the SNaN is converted to a QNaN or the source QNaN is returned.

In 64-bit mode, using a REX prefix in the form of REX.R permits this instruction to access additional registers (XMM8-XMM15).

Pseudo Code

DEST[31:0] = APPROXIMATE(1.0/SQRT(SRC[31:0]));
DEST[63:32] = APPROXIMATE(1.0/SQRT(SRC[63:32]));
DEST[95:64] = APPROXIMATE(1.0/SQRT(SRC[95:64]));
DEST[127:96] = APPROXIMATE(1.0/SQRT(SRC[127:96]));

Exceptions

SIMD Floating-Point Exceptions

None.

64-Bit Mode Exceptions

Exception Description
#UD If CR0.EM[bit 2] = 1. If CR4.OSFXSR[bit 9] = 0. If CPUID.01H:EDX.SSE[bit 25] = 0. If the LOCK prefix is used.
#NM If CR0.TS[bit 3] = 1.
#PF(fault-code) For a page fault.
#GP(0) If the memory address is in a non-canonical form. If memory operand is not aligned on a 16-byte boundary, regardless of segment.
#SS(0) If a memory address referencing the SS segment is in a non- canonical form.

Compatibility Mode Exceptions

Same exceptions as in protected mode.

Virtual-8086 Mode Exceptions

Exception Description
#PF(fault-code) For a page fault.
Same exceptions as in real address mode.

Real-Address Mode Exceptions

Exception Description
#UD If CR0.EM[bit 2] = 1. If CR4.OSFXSR[bit 9] = 0. If CPUID.01H:EDX.SSE[bit 25] = 0. If the LOCK prefix is used.
#NM If CR0.TS[bit 3] = 1.
#GP If a memory operand is not aligned on a 16-byte boundary, regardless of segment. If any part of the operand lies outside the effective address space from 0 to FFFFH.

Protected Mode Exceptions

Exception Description
#UD If CR0.EM[bit 2] = 1. If CR4.OSFXSR[bit 9] = 0. If CPUID.01H:EDX.SSE[bit 25] = 0. If the LOCK prefix is used.
#NM If CR0.TS[bit 3] = 1.
#PF(fault-code) For a page fault.
#SS(0) For an illegal address in the SS segment.
#GP(0) For an illegal memory operand effective address in the CS, DS, ES, FS or GS segments. If a memory operand is not aligned on a 16-byte boundary, regardless of segment.