3-349
INSTRUCTION SET REFERENCE
LDS/LES/LFS/LGS/LSSLoad Far Pointer
Description
These instructions load a far pointer (segment selector and offset) from the second operand
(source operand) into a segment register and the first operand (destination operand). The source
operand specifies a 48-bit or a 32-bit pointer in memory depending on the current setting of the
operand-size attribute (32 bits or 16 bits, respectively). The instruction opcode and the destina-
tion operand specify a segment register/general-purpose register pair. The 16-bit segment
selector from the source operand is loaded into the segment register specified with the opcode
(DS, SS, ES, FS, or GS). The 32-bit or 16-bit offset is loaded into the register specified with the
destination operand.
If one of these instructions is executed in protected mode, additional information from the
segment descriptor pointed to by the segment selector in the source operand is loaded in the
hidden part of the selected segment register.
Also in protected mode, a null selector (values 0000 through 0003) can be loaded into DS, ES,
FS, or GS registers without causing a protection exception. (Any subsequent reference to a
segment whose corresponding segment register is loaded with a null selector, causes a general-
protection exception (#GP) and no memory reference to the segment occurs.)
Opcode
Instruction
Description
C5 /r
LDS r16,m16:16
Load DS:r16 with far pointer from memory
C5 /r
LDS r32,m16:32
Load DS:r32 with far pointer from memory
0F B2 /r
LSS r16,m16:16
Load SS:r16 with far pointer from memory
0F B2 /r
LSS r32,m16:32
Load SS:r32 with far pointer from memory
C4 /r
LES r16,m16:16
Load ES:r16 with far pointer from memory
C4 /r
LES r32,m16:32
Load ES:r32 with far pointer from memory
0F B4 /r
LFS r16,m16:16
Load FS:r16 with far pointer from memory
0F B4 /r
LFS r32,m16:32
Load FS:r32 with far pointer from memory
0F B5 /r
LGS r16,m16:16
Load GS:r16 with far pointer from memory
0F B5 /r
LGS r32,m16:32
Load GS:r32 with far pointer from memory
