FRESTORE
Restore Internal Stal:e
(Privileged Instruction)
FRESTORE
IDLE:
This state frame is 28 ($1C) bytes long in the MC68881, and 60 ($3C) bytes
long in the MC68882. An FRESTORE operation with this size state frame
causes the FPCP to be restored to the idle state, waiting for the initiation
of the next instruction. Exceptions that were pending before the execution
of the previous FSAVE instruction are pending following the execution of
the FRESTORE instruction. The programmer's model is not affected by
loading this type of state frame.
BUSY:
This state frame is 184 ($B8) bytes long in the MC68881 and 216 ($D8)
bytes long in the MC68882. An FRESTORE operation with this size state
frame causes the FPCP to be restored to the busy state, executing the
instruction that was suspended by a previous FSAVE operation. The pro-
grammer's model is not affected by loading this type of state frame (although
the completion of the suspended instruction after the restore is executed
may modify the programmer's model).
Status Register: Cleared if the state size is NULL, otherwise not affected
Instruction Format:
15 14
13 12
11 10 9 8 7 6 S
COPROCESSOR
1 1 1 1 IO 1 0 l
4 3 2 1 0
EFFECTIVE ADDRESS
MODE ( REGISTER
Instruction Fields:
Coprocessor ID Field -- Specifies which coprocessor fn 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 state frame. Only
postincrement or control addressing modes are allowed as shown:
Addressing Mode
Dn
An
(An)
(An) +
- (An)
(d16,An)
(ds,An,Xn)
(bd,An,Xn)
([bd,An,Xn],od)
([bd,An],Xn,od)
Mode Register
010 reg. number:An
011
reg. number:An
101 reg. number:An
110 reg. number:An
110 reg, number:An
110 reg. number:An
110 reg. number:An
Addressing Mode Mode Register
(xxx).W 111 000
(xxx).L 111 001
#<data>
-- --
(d16,PC) 111 010
(d8,PC,Xn) 111 011
(bd,PC,Xn) 111 011
([bd,PC,XnJ,od) 111 011
([bd,PC],Xn,od) 111 011
MC68881/MC68882 USER'S MANUAL FREESCALE
4-89
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