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MC68060 Instructions
MOTOROLA
M68060 USER’S MANUAL
D-13
FRESTORE
Restore Internal
FRESTORE
Floating-Point State
(MC68060 only)
Operation:
If in Supervisor State
Then FPU State Frame
Internal State
Else TRAP
Assembler
Syntax:
FRESTORE<ea>
Attributes:
Unsized
Description:
Aborts the execution of any floating-point operation in progress and loads
a new floating-point unit internal state from the state frame located at the effective
address. The state frame always contains three long words. The third byte from of the
state frame specifies the frame format. The fourth byte of the state frame contains the
exception vector. If the frame format is invalid, the FRESTORE aborts, and a format
exception is generated. If the frame format is valid, the state frame is loaded, starting
at the specified location and proceeding through higher addresses.
The FRESTORE instruction does not normally affect the programmer’s model registers
of the floating-point coprocessor, except for the NULL state frame. The FRESTORE
instruction is used with the FMOVEM instruction to perform a full context restoration of
the floating-point unit, including the floating-point data registers and system control reg-
isters. To accomplish a complete restoration, the FMOVEM instructions are first exe-
cuted to load the programmer’s model, followed by the FRESTORE instruction to load
the internal state.
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