Справочник Пользователя для AMD LX 900@1.5W
AMD Geode™ LX Processors Data Book
625
Instruction Set
33234H
8.1.5
s-i-b Byte (Scale, Indexing, Base)
The s-i-b fields provide scale factor, indexing, and a base field for address selection. The ss, index, and base fields are
described next.
described next.
8.1.5.1
ss Field (Scale Selection)
The ss field (Table 8-13) specifies the scale factor used in the offset mechanism for address calculation. The scale factor
multiplies the index value to provide one of the components used to calculate the offset address.
multiplies the index value to provide one of the components used to calculate the offset address.
8.1.5.2
Index Field (Index Selection)
The index field (Table 8-14) specifies the index register used by the offset mechanism for offset address calculation. When
no index register is used (index field = 100), the ss value must be 00 or the effective address is undefined.
no index register is used (index field = 100), the ss value must be 00 or the effective address is undefined.
Table 8-13. ss Field Encoding
ss Field
Scale Factor
00
x1
01
x2
01
x4
11
x8
Table 8-14. index Field Encoding
Index Field
Index Register
000
EAX
001
ECX
010
EDX
011
EBX
100
none
101
EBP
110
ESI
111
EDI