PMAXSD

Maximum of Packed Signed Dword Integers

Opcodes

Hex Mnemonic Encoding Long Mode Legacy Mode Description
66 0F 38 3D /r PMAXSD xmm1, xmm2/m128 A Valid Valid Compare packed signed dword integers in xmm1 and xmm2/m128 and store packed maximum values in xmm1.

Instruction Operand Encoding

Op/En Operand 0 Operand 1 Operand 2 Operand 3
A NA NA ModRM:r/m (r) ModRM:reg (r, w)

Description

Compares packed signed dword integers in the destination operand (first operand) and the source operand (second operand), and returns the maximum for each packed value in the destination operand.

Pseudo Code

IF (DEST[31:0] > SRC[31:0])
	DEST[31:0] = DEST[31:0];
ELSE
	DEST[31:0] = SRC[31:0];
FI;
IF (DEST[63:32] > SRC[63:32])
	DEST[63:32] = DEST[63:32];
ELSE
	DEST[63:32] = SRC[63:32];
FI;
IF (DEST[95:64] > SRC[95:64])
	DEST[95:64] = DEST[95:64];
ELSE
	DEST[95:64] = SRC[95:64];
FI;
IF (DEST[127:96] > SRC[127:96])
	DEST[127:96] = DEST[127:96];
ELSE
	DEST[127:96] = SRC[127:96];
FI;

Flags Affected

None

Exceptions

64-Bit Mode Exceptions

Exception Description
#UD If EM in CR0 is set. If OSFXSR in CR4 is 0. If CPUID feature flag ECX.SSE4_1 is 0. If LOCK prefix is used. Either the prefix REP (F3h) or REPN (F2H) is used.
#NM If TS in CR0 is set.
#PF(fault-code) For a page fault.
#SS(0) If a memory address referencing the SS segment is in a non-canonical form.
#GP(0) If the memory address is in a non-canonical form. If a memory operand is not aligned on a 16-byte boundary, regardless of segment.

Compatibility Mode Exceptions

Same exceptions as in Protected Mode.

Virtual-8086 Mode Exceptions

Exception Description
#PF(fault-code) For a page fault.
Same exceptions as in Real Address Mode.

Real-Address Mode Exceptions

Exception Description
#UD If CR0.EM[bit 2] = 1. If CR4.OSFXSR[bit 9] = 0. If CPUID.01H:ECX.SSE4_1[bit 19] = 0. If LOCK prefix is used. Either the prefix REP (F3h) or REPN (F2H) is used.
#NM If CR0.TS[bit 3] = 1.
#GP(0) if any part of the operand lies outside of the effective address space from 0 to 0FFFFH. If a memory operand is not aligned on a 16-byte boundary, regardless of segment.

Protected Mode Exceptions

Exception Description
#UD If CR0.EM[bit 2] = 1. If CR4.OSFXSR[bit 9] = 0. If CPUID.01H:ECX.SSE4_1[bit 19] = 0. If LOCK prefix is used. Either the prefix REP (F3h) or REPN (F2H) is used.
#NM If CR0.TS[bit 3] = 1.
#PF(fault-code) For a page fault.
#SS(0) For an illegal address in the SS segment.
#GP(0) For an illegal memory operand effective address in the CS, DS, ES, FS, or GS segments. If a memory operand is not aligned on a 16-byte boundary, regardless of segment.