FNSTSW
REG0=XED_REG_AX:w:IMPL REG1=XED_REG_X87STATUS:rw:SUPP
x86_64 X86_LEGACY X87_ALU X87 source: xed
XED_FNSTSW_X86_LEGACY_ONEBYTE_DF_420511
Encoding
| encoding_kind | X86_LEGACY |
| opcode_bytes | DF |
| opcode_map | ONEBYTE |
| mandatory_prefix | - |
| has_modrm | True |
| modrm.reg = /4 | /4 |
| attributes | X87_NOWAIT X87_CONTROL NOTSX |
| cpl | 3 |
| raw_encoding | 0xDF MOD[0b11] MOD=3 REG[0b100] RM[0b000] |
Operands (2)
| # | Role | Kind | Class / Reg | Width | Access | Visibility | Encoded in |
|---|---|---|---|---|---|---|---|
| 0 | REG0 | REG | (=AX) | w | W | IMPLICIT | MODRM_REG |
| 1 | REG1 | REG | RW | SUPPRESSED | MODRM_REG |
Micro-ops sequence (0)
No micro-ops authored for this encoding. Emulator semantics not yet defined — decoder still works.