|Opcode*/Instruction||Op/En||64/32 bit Mode Support||CPUID Feature Flag||Description|
|66 0F 3A 0B /r ib ROUNDSD xmm1, xmm2/m64, imm8||RMI||V/V||SSE4_1||Round the low packed double precision floating-point value in xmm2/m64 and place the result in xmm1. The rounding mode is determined by imm8.|
|VEX.NDS.LIG.66.0F3A.WIG 0B /r ib VROUNDSD xmm1, xmm2, xmm3/m64, imm8||RVMI||V/V||AVX||Round the low packed double precision floating-point value in xmm3/m64 and place the result in xmm1. The rounding mode is determined by imm8. Upper packed double precision floating-point value (bits[127:64]) from xmm2 is copied to xmm1[127:64].|
|Op/En||Operand 1||Operand 2||Operand 3||Operand 4|
|RMI||ModRM:reg (w)||ModRM:r/m (r)||imm8||NA|
|RVMI||ModRM:reg (w)||VEX.vvvv (r)||ModRM:r/m (r)||imm8|
Round the DP FP value in the lower qword of the source operand (second operand) using the rounding mode spec-ified in the immediate operand (third operand) and place the result in the destination operand (first operand). The rounding process rounds a double-precision floating-point input to an integer value and returns the integer result as a double precision floating-point value in the lowest position. The upper double precision floating-point value in the destination is retained.
The immediate operand specifies control fields for the rounding operation, three bit fields are defined and shown in Figure 4-20. Bit 3 of the immediate byte controls processor behavior for a precision exception, bit 2 selects the source of rounding mode control. Bits 1:0 specify a non-sticky rounding-mode value (Table 4-15 lists the encoded values for rounding-mode field).
The Precision Floating-Point Exception is signaled according to the immediate operand. If any source operand is an SNaN then it will be converted to a QNaN. If DAZ is set to ‘1 then denormals will be converted to zero before rounding.
128-bit Legacy SSE version: The first source operand and the destination operand are the same. Bits (VLMAX-1:64) of the corresponding YMM destination register remain unchanged.
VEX.128 encoded version: Bits (VLMAX-1:128) of the destination YMM register are zeroed.
IF (imm = ‘1) THEN // rounding mode is determined by MXCSR.RC DEST[63:0] ← ConvertDPFPToInteger_M(SRC[63:0]); ELSE // rounding mode is determined by IMM8.RC DEST[63:0] ← ConvertDPFPToInteger_Imm(SRC[63:0]); FI; DEST[127:63] remains unchanged ;
ROUNDSD (128-bit Legacy SSE version)
DEST[63:0] ← RoundToInteger(SRC[63:0], ROUND_CONTROL) DEST[VLMAX-1:64] (Unmodified)
VROUNDSD (VEX.128 encoded version)
DEST[63:0] ← RoundToInteger(SRC2[63:0], ROUND_CONTROL) DEST[127:64] ← SRC1[127:64] DEST[VLMAX-1:128] ← 0
__m128d mm_round_sd(__m128d dst, __m128d s1, int iRoundMode); __m128d mm_floor_sd(__m128d dst, __m128d s1); __m128d mm_ceil_sd(__m128d dst, __m128d s1);
Invalid (signaled only if SRC = SNaN)
Precision (signaled only if imm = ‘0; if imm = ‘1, then the Precision Mask in the MXSCSR is ignored and preci-sion exception is not signaled.)
Note that Denormal is not signaled by ROUNDSD.
See Exceptions Type 3.