Intel 64 and IA-32 Architectures Software Developers Manual Volume 2B, Instruction Set Reference, N-Z

A-28 Vol. 2B
OPCODE MAP
A.5.2.6 Escape Opcodes with DD as First Byte
Table A-17 and A-18 contain maps for escape instruction opcodes that begin with
DDH. Table A-17 shows the map if the ModR/M byte is in the range of 00H-BFH. Here,
the value of bits 3-5 (the nnn field in Figure A-1) selects the instruction.
Table A-18 shows the map if the ModR/M byte is outside the range of 00H-BFH. The
first digit of the ModR/M byte selects the table row and the second digit selects the
column.
Table A-17. DD Opcode Map When ModR/M Byte is Within 00H to BFH
*
nnn Field of ModR/M Byte
000B 001B 010B 011B 100B 101B 110B 111B
FLD double-
real
FISTTP
integer64
FST double-
real
FSTP double-
real
FRSTOR
98/108bytes
FSAVE
98/108bytes
FSTSW 2
bytes
NOTES:
*
All blanks in all opcode maps are reserved and must not be used. Do not depend on the operation of unde-
fined or reserved locations.
Table A-18. DD Opcode Map When ModR/M Byte is Outside 00H to BFH *
0 123456 7
CFFREE
ST(0) ST(1) ST(2) ST(3) ST(4) ST(5) ST(6) ST(7)
DFST
ST(0) ST(1) ST(2) ST(3) ST(4) ST(5) ST(6) ST(7)
E FUCOM
ST(0),ST(0) ST(1),ST(0) ST(2),ST(0) ST(3),ST(0) ST(4),ST(0) ST(5),ST(0) ST(6),ST(0) ST(7),ST(0)
F
89ABCDEF
C
DFSTP
ST(0) ST(1) ST(2) ST(3) ST(4) ST(5) ST(6) ST(7)
E FUCOMP
ST(0) ST(1) ST(2) ST(3) ST(4) ST(5) ST(6) ST(7)
F
NOTES:
*
All blanks in all opcode maps are reserved and must not be used. Do not depend on the operation of unde-
fined or reserved locations.