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622 AMD Geode™ LX Processors Data Book
Instruction Set
33234H
8.1.2.4 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 8-7. The values shown in Table 8-7 are the only valid encod-
ings for the eee bits.
8.1.3 mod and r/m Byte (Memory Addressing)
The mod and r/m fields within the mod r/m byte select the type of memory addressing to be used. Some instructions use a
fixed addressing mode (e.g., PUSH or POP) and therefore, these fields are not present. Table 8-8 lists the addressing method
when 16-bit addressing is used and a mod r/m byte is present. Some mod r/m field encodings are dependent on the w field
and are shown in Table 8-9.
Table 8-7. eee Field Encoding
eee Field Register Type Base Register
000 Control Register CR0
010 Control Register CR2
011 Control Register CR3
100 Control Register CR4
000 Debug Register DR0
001 Debug Register DR1
010 Debug Register DR2
011 Debug Register DR3
110 Debug Register DR6
111 Debug Register DR7
000 Test Register TR0
001 Test Register TR1
010 Test Register TR2
011 Test Register TR3
100 Test Register TR4
101 Test Register TR5
110 Test Register TR6
111 Test Register TR7
Table 8-8. mod r/m Field Encoding
mod Field r/m Field
16-Bit Address Mode with
mod r/m Byte (Note 1)
32-Bit Address Mode with mod r/m Byte and
No s-i-b Byte Present
(Note 1)
00 000 DS:[BX+SI] DS:[EAX]
00 001 DS:[BX+DI] DS:[ECX]
00 010 SS:[BP+SI] DS:[EDX]
00 011 SS:[BP+DI] DS:[EBX]
00 100 DS:[SI] s-i-b is present (See Table 8-15 on page 626)
00 101 DS:[DI] DS:[d32]
00 110 DS:[d16] DS:[ESI]
00 111 DS:[BX] DS:[EDI]