GXM Datasheet, PDF (204/244 Pages) National Semiconductor (TI) – Geode™ GXm Processor Integrated x86 Solution with MMX Support

Instruction Set (Continued)
9.1.2.2 d Field (Operand Direction)
When used, the d field (bit 1) determines which operand is
taken as the source operand and which operand is taken
as the destination. See Table 9-5.
9.1.2.3 s Field (Immediate Data Field Size)
When used, the s field (bit 1) determines the size of the
immediate data field. If the s bit is set, the immediate field
of the opcode is 8 bits wide and is sign-extended to match
the operand size of the opcode. See Table 9-6.
9.1.2.4 eee Field (MOV-Instruction Register
Selection)
The eee field (bits [5:3]) is used to select the control,
debug and test registers in the MOV instructions. The type
of register and base registers selected by the eee field are
listed in Table 9-7. The values shown in Table 9-7 are the
only valid encodings for the eee bits.
Table 9-5. d Field Encoding
d
Field
Direction of
Operation
Source
Operand
Destination
Operand
0 Register-to-Register reg
or
Register-to-Memory
mod r/m
or
mod ss-index-
base
1 Register-to-Register mod r/m
reg
or
or
Memory-to-Register mod ss-index-
base
Table 9-6. s Field Encoding
Immediate Field Size
s
Field
8-Bit
16-Bit
32-Bit
Operand Size Operand Size Operand Size
0 (or not
present)
1
8 bits
8 bits
16 bits
32 bits
8 bits
8 bits
(sign-extended) (sign-extended)
Table 9-7. eee Field Encoding
eee Field
000
010
011
100
000
001
010
011
110
111
011
100
101
110
111
Register Type
Control Register
Control Register
Control Register
Control Register
Debug Register
Debug Register
Debug Register
Debug Register
Debug Register
Debug Register
Test Register
Test Register
Test Register
Test Register
Test Register
Base Register
CR0
CR2
CR3
CR4
DR0
DR1
DR2
DR3
DR6
DR7
TR3
TR4
TR5
TR6
TR7
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