4
FMOVE Move System Control Register FMOVE
Operation:
Assembler
Syntax:
Attributes:
Description:
Source B Destination
FMOVE.L <ea>,FPcr
FMOVE.L FPcr,<ea>
Size = (Long)
Moves the contents of a floating-point system control register into or out
of the FPCP (the control registers are the FPCR, FPSR and FPIAR). The external operand
may be in memory or a main processor register. A 32-bit transfer is always performed,
even though the system control register may not have 32 implemented bits. Unim-
plemented bits of a control register are read as zeros and are ignored during writes
(but must be zero for compatability with future devices).
This instruction does not cause pending exceptions (other than protocol violations)
to be reported to the main processor. Furthermore, a write to the FPCR exception
enable byte or the FPSR exception status byte cannot generate a new exception,
regardless of the value written.
Status Register: Changed only if the destination is the FPSR; in which case all bits are
modified to reflect the value of the source operand.
Instruction Format:
15 14 13
I I 1
I 0 dr
12 11 10 9 8 7 6 5 4 3 2 1 g
COPROCESSOR
I EFFECTIVFq ADDRESS
l ( z
ID
0 0 0 MODE | REGISTER
REGISTER { } '~
SELECT 0 ~ 0 0 0 0 I
0 0 ! ~ ! 0
Instruction Fields:
Coprocessor ID Field -- Specifies which coprocessor in the system is to execute this
instruction. Freescale assemblers default to ID= 1 for the FPCP.
Effective Address Field -- Determines the addressing mode for the operation:
Memory-to-Register
Addressing Mode
(xxx).W
(xxx).L
#<data>
(d16,PCl
(ds,PC,Xn)
(bd,PC,Xn)
([bd,PC,Xn],odJ
([bd.PC],Xn,od)
Addressing Mode Mode Register
Dn 000
reg. number:Dn
An* 001
reg. number:An
{An) 010
reg, number:An
(An)+ 011
reg. number:An
-(An) 100
reg. number:An
(d16,An) 101
reg. number:An
(d8,An,Xn) 110
reg, number:An
(bd,An,Xn) 110
reg. number:An
Ilbd,An.XnJ,odJ 110
reg. number:An
([bd,An],Xn,od) 110
reg. number:An
I Mode Register
111 030
111 I 100
i
111 I 010
111
t
011
111 011
111 011
111 011
*Only if the source register is the
FPIAR.
FREESCALE
4-70
MC68881/MC68882 USER'S MANUAL
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