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3-368 Vol. 2A FRNDINT—Round to Integer
INSTRUCTION SET REFERENCE, A-M
FRNDINT—Round to Integer
Description
Rounds the source value in the ST(0) register to the nearest integral value,
depending on the current rounding mode (setting of the RC field of the FPU control
word), and stores the result in ST(0).
If the source value is ∞, the value is not changed. If the source value is not an integral
value, the floating-point inexact-result exception (#P) is generated.
This instruction’s operation is the same in non-64-bit modes and 64-bit mode.
Operation
ST(0) ← RoundToIntegralValue(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.
#D Source operand is a denormal value.
#P Source operand is not an integral value.
Protected Mode Exceptions
#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 Exceptions
Same exceptions as in protected mode.
Virtual-8086 Mode Exceptions
Same exceptions as in protected mode.
Opcode Instruction 64-Bit
Mode
Compat/
Leg Mode
Description
D9 FC FRNDINT Valid Valid Round ST(0) to an integer.