FSQRT
Square Root
stableVMJITAOTinstruction
Encodings
| Opcode | Instruction | Op/En | 64-bit | Compat/Legacy | Description |
|---|---|---|---|---|---|
D9 FA | FSQRT | Valid | Valid | Computes square root of ST(0) and stores the result in ST(0). |
Measured cost
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Description
Computes the square root of the source value in the ST(0) register and stores the result in ST(0).
The following table shows the results obtained when taking the square root of various classes of numbers, assuming that neither overflow nor underflow occurs.
FSQRT Results
| SRC (ST(0)) | DEST (ST(0)) |
|---|---|
| - | * |
| -F | * |
| -0 | -0 |
| +0 | +0 |
| +F | +F |
| + | + |
| NaN | NaN |
Operation
ST(0) := SquareRoot(ST(0));
FPU Flags Affected
C1 Set to 0 if stack underflow occurred.
Set if result was rounded up; cleared otherwise.
C0, C2, C3 Undefined.Floating-Point Exceptions
#IS Stack underflow occurred.#IA Source operand is an SNaN value or unsupported format.Source operand is a negative value (except for -0).
#D Source operand is a denormal value.#P Value cannot be represented exactly in destination format.Exceptions
Protected mode
#NM | CR0.EM[bit 2] or CR0.TS[bit 3] = 1. |
#MF | If there is a pending x87 FPU exception. |
#UD | If the LOCK prefix is used. |
Real address mode
| Same exceptions as in protected mode. |
Virtual-8086 mode
| Same exceptions as in protected mode. |
Compatibility mode
| Same exceptions as in protected mode. |
64-bit mode
| Same exceptions as in protected mode. |