Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3, Manual

Page: 1850 / 1898

4:548 Volume 4: IA-32 SSE Instruction Reference
RSQRTSS: Scalar Single-FP Square Root Reciprocal
Operation: xmm1[31-0] = approx (1.0/sqrt(xmm2/m32[31-0]));
xmm1[63-32] = xmm1[63-32];
xmm1[95-64] = xmm1[95-64];
xmm1[127-96] = xmm1[127-96];
Description:
RSQRTSS returns an approximation of the reciprocal of the square root of the lowest SP
FP number from xmm2/m32; the upper 3 fields are passed through from xmm1. The
relative error for this approximation is Error, which satisfies:
|Error| <= 1.5x2
-12
Numeric Exceptions:
None.
Protected Mode Exceptions:
#GP(0) for an illegal memory operand effective address in the CS, DS, ES, FS or GS
segments; #SS(0) for an illegal address in the SS segment; #PF (fault-code) for a page
fault; #UD if CR0.EM = 1; #NM if TS bit in CR0 is set; #AC for unaligned memory
reference. To enable #AC exceptions, three conditions must be true(CR0.AM is set;
EFLAGS.AC is set; current CPL is 3).
Real Address Mode Exceptions:
Interrupt 13 if any part of the operand would lie outside of the effective address space
from 0 to 0FFFFH;
#UD if CR0.EM = 1; #NM if TS bit in CR0 is set.
Virtual 8086 Mode Exceptions:
Same exceptions as in Real Address Mode; #AC for unaligned memory reference if the
current privilege level is 3; #PF (fault-code) for a page fault.
Additional Itanium System Environment Exceptions
Itanium Reg Faults Disabled FP Register Fault if PSR.dfl is 1, NaT Register
Consumption Fault
Itanium Mem Faults VHPT Data Fault, Data TLB Fault, Alternate Data TLB Fault, Data
Page Not Present Fault, Data NaT Page Consumption Abort, Data
Key Miss Fault, Data Key Permission Fault, Data Access Rights
Fault, Data Access Bit Fault
Comments:
Example:
RSQRTSS is not affected by the rounding control in MXCSR. Denormal inputs are
treated as zeros (of the same sign).
Opcode Instruction Description
F3,0F,52,/r RSQRTSS xmm1, xmm2/m32 Return an approximation of the square root of the reciprocal of
the lowest SP FP number in XMM2/Mem.