x86 Instruction Set Reference


Round to Integer

Opcode Mnemonic Description
D9 FC FRNDINT Round ST(0) to an integer.

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 infinite, the value is not changed. If the source value is not an integral value, the floating-point inexact-result exception (#P) is generated.

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
#ISStack underflow occurred.
#ISStack underflow occurred.
#IASource operand is an SNaN value or unsupported format.
#DSource operand is a denormal value.
Protected Mode Exceptions
#NMEM or TS in CR0 is set.
Real-Address Mode Exceptions
#NMEM or TS in CR0 is set.
Virtual-8086 Mode Exceptions
#NMEM or TS in CR0 is set.
Instruction Latency Throughput Execution Unit