Floating Point Instructions
5-80 M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL MOTOROLA
FMOVE Move Floating-Point FMOVE
System Control Register
(MC6888X, MC68040)
Operation: Source → Destination
Assembler FMOVE.L < ea > ,FPCR
Syntax: FMOVE.L FPCR, < ea >
Attributes: Size = (Long)
Description: Moves the contents of a floating-point system control register (floating-point
control register, floating-point status register, or floating-point instruction address
register) to or from an effective address. A 32-bit transfer is always performed, even
though the system control register may not have 32 implemented bits. Unimplemented
bits of a control register are read as zeros and are ignored during writes (must be zero
for compatibility with future devices). For the MC68881, this instruction does not cause
pending exceptions (other than protocol violations) to be reported. Furthermore, a write
to the floating-point control register exception enable byte or the floating-point status
register exception status byte cannot generate a new exception, regardless of the
value written.
Floating-Point Status Register: Changed only if the destination is the floating-point status
register, in which case all bits are modified to reflect the value of the source operand.
Instruction Format:
1514131211109876543210
1111
COPROCESSOR
ID
000
EFFECTIVE ADDRESS
MODE REGISTER
10dr
REGISTER
SELECT
0000000000
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