Motorola CPU32 Bedienungsanleitung PDF herunterladen (Seite 393)

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Floating Point Instructions

MOTOROLA M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL 5-91

FMOVEM Move Multiple Floating-Point FMOVEM

Control Registers

(MC6888X, MC68040)

Operation: Register List → Destination

Source → Register List

Assembler FMOVEM.L < list > , < ea >

Syntax: FMOVEM.L < ea > , < list >

Attributes: Size = (Long)

Description: Moves one or more 32-bit values into or out of the speciﬁed system control

registers. Any combination of the three system control registers may be speciﬁed. The

registers are always moved in the same order, regardless of the addressing mode

used; the ﬂoating-point control register is moved ﬁrst, followed by the ﬂoating-point

status register, and the ﬂoating-point instruction address register is moved last. If a

registers is the same. The ﬁrst register is transferred between the ﬂoating-point unit and

the speciﬁed address, with successive registers located up through higher addresses.

For the MC68881, this instruction does not cause pending exceptions (other than pro-

tocol violations) to be reported. Furthermore, a write to the floating-point control regis-

ter exception enable byte or the floating-point status register exception status byte

connot generate a new exception, despite the value written.

When more than one register is moved, the memory or memory- alterable addressing

modes can be used as shown in the addressing mode tables. If the addressing mode

is predecrement, the address register is first decremented by the total size of the reg-

ister images to be moved (i.e., four times the number of registers), and then the regis-

ters are transferred starting at the resultant address. For the postincrement addressing

mode, the selected registers are transferred to or from the specified address, and then

the address register is incremented by the total size of the register images transferred.

If a single system control register is selected, the data register direct addressing mode

may be used; if the only register selected is the floating-point instruction address reg-

ister, then the address register direct addressing mode is allowed. Note that if a single

control register instruction.

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