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8.2.3.5 ENCODING OF OPERATION DIRECTION
(d) FIELD
In
many two·operand instructions the d field is pres·
ent to indicate which operand is considered the
source and which is the destination.
d
Direction
of
Operation
0
Register/Memory <- -Register
"reg"
Field Indicates Source Operand;
"mod
r/m"
or "mod ss index base" Indicates
Destination Operand
1 Register <- - Register/Memory
"reg"
Field Indicates Destination Operand;
"mod
r/m"
or "mod ss index base" Indicates
Source Operand
8.2.3.6 ENCODING OF SIGN-EXTEND (s) FIELD
The s field occurs primarily to instructions with im-
mediate data fields. The s field has an effect only if
the size
of
the immediate data is 8 bits and is being
placed
in
a 1S-bit or 32-bit destination.
Effect
on
Effect
on
s
Immediate Data8 Immediate Data
16132
None None
1 Sign-Extend Data8 to Fill None
1S-Bit or 32-Bit Destination
8.2.3.7
ENCODING OF CONDITIONAL TEST
(tttn)
FIELD
For the conditional instructions (conditional jumps
and set on condition), tttn is encoded with n
indicat-
ing to use the condition
(n
=
0)
or its negation
(n
=
1),
and ttt giving the condition to test.
131
Mnemonic Condition
tttn
0
Overflow 0000
NO
No Overflow
0001
B/NAE
Below/Not Above or Equal 0010
NB/AE
Not
Below/Above or Equal
0011
E/Z
Equal/Zero 0100
NE/NZ
Not EquallNot Zero
0101
BEINA
Below or EquallNot Above 0110
NBE/A
Not Below or Equal/ Above
0111
S
Sign 1000
NS
Not Sign
1001
PIPE Parity/Parity Even 1010
NP/PO
Not Parity/Parity Odd
1011
L/NGE Less Than/Not Greater or Equal 1100
NL/GE
Not Less Than/Greater or
Equal
1101
LEING Less Than or Equal/Greater Than 1110
NLE/G
Not Less or
Equal/Greater Than
1111
8.2.3.8 ENCODING OF CONTROL
OR
DEBUG
OR
TEST REGISTER (eee) FIELD
For the loading and storing of the Control, Debug
and Test registers.
When
Interpreted
as
Control
Register Field
eeeCode
Reg Name
000
CRO
010 CR2
011
CR3
Do
not use any other encoding
When
Interpreted
as
Debug Register Field
eeeCode
Reg Name
000
DRO
001
DR1
010 DR2
011
DR3
110
DRS
111
DR7
Do
not use any other encoding
When
Interpreted
as
Test
Register Field
eeeCode
Reg Name
110
TRS
111
TR7
Do not use any other encoding