Intel 253666-024US - Manual (Page 298)

3-252 Vol. 2A CVTTSS2SI—Convert with Truncation Scalar Single-Precision Floating-Point Value to
Doubleword Integer
INSTRUCTION SET REFERENCE, A-M
CVTTSS2SI—Convert with Truncation Scalar Single-Precision Floating-
Point Value to Doubleword Integer
Description
Converts a single-precision floating-point value in the source operand (second
operand) to a signed doubleword integer (or signed quadword integer if operand size
is 64 bits) in the destination operand (first operand). The source operand can be an
XMM register or a 32-bit memory location. The destination operand is a general-
purpose register. When the source operand is an XMM register, the single-precision
floating-point value is contained in the low doubleword of the register.
When a conversion is inexact, a truncated (round toward zero) result is returned. If a
converted result is larger than the maximum signed doubleword integer, the floating-
point invalid exception is raised. If this exception is masked, the indefinite integer
value (80000000H) is returned.
In 64-bit mode, the instruction can access additional registers (XMM8-XMM15,
R8-R15) when used with a REX.R prefix. Use of the REX.W prefix promotes the
instruction to 64-bit operation. See the summary chart at the beginning of this
section for encoding data and limits.
Operation
IF 64-Bit Mode and OperandSize = 64
THEN
DEST[63:0] ← Convert_Single_Precision_Floating_Point_To_
Integer_Truncate(SRC[31:0]);
ELSE
DEST[31:0] ← Convert_Single_Precision_Floating_Point_To_
Integer_Truncate(SRC[31:0]);
FI;
Opcode Instruction 64-Bit
Mode
Compat/
Leg Mode
Description
F3 0F 2C /r CVTTSS2SI r32,
xmm/m32
Valid Valid Convert one single-precision
floating-point value from
xmm/m32 to one signed
doubleword integer in r32
using truncation.
F3 REX.W 0F 2C /r CVTTSS2SI r64,
xmm/m32
Valid N.E. Convert one single-precision
floating-point value from
xmm/m32 to one signed
quadword integer in r64 using
truncation.