-
Notifications
You must be signed in to change notification settings - Fork 97
FCHS
FCHS — Change Sign
Opcode | Instruction | 64-Bit Mode | Compat/ Leg Mode | Description |
D9 E0 | FCHS | Valid | Valid | Complements sign of ST(0). |
Complements the sign bit of ST(0). This operation changes a positive value into a negative value of equal magni- tude or vice versa. The following table shows the results obtained when changing the sign of various classes of numbers.
Table 3-20. FCHS Results
ST(0) SRC | ST(0) DEST |
− ∞ | + ∞ |
− F | + F |
− 0 | + 0 |
+ 0 | − 0 |
+ F | − F |
+ ∞ | − ∞ |
NaN | NaN |
* F means finite floating-point value.
This instruction’s operation is the same in non-64-bit modes and 64-bit mode.
SignBit(ST(0)) ← NOT (SignBit(ST(0)));
C1 Set to 0. C0, C2, C3 Undefined.
#IS Stack underflow occurred.
#NM CR0.EM[bit 2] or CR0.TS[bit 3] = 1.
#UD If the LOCK prefix is used.
Same exceptions as in protected mode.
Same exceptions as in protected mode.
Same exceptions as in protected mode.
Same exceptions as in protected mode.
Source: Intel® Architecture Software Developer's Manual (May 2018)
Generated: 5-6-2018