4
FTRAPcc FTRAPcc
Trap Conditionally
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.
Mode Field -- Specifies the form of the instruction.
010 -- The instruction is followed by a word operand.
011 -- The instruction is followed by a long word operand.
100 -- The instruction has no operand.
Conditional Predicate Field -- Specifies one of 32 conditional tests as described in 4.4
CONDITIONAL TEST DEFINITIONS.
Operand Field-- Contains an optional word or long word operand that is user defined.
NOTE
When a BSUN exception occurs, a pre-instruction exception is taken by the
main processor. If the exception handler returns without modifying the image
of the PC on the stack frame (to point to the instruction following the FTRAPcc),
it must clear the cause of the exception (by clearing the NAN bit or disabling
the BSUN trap) or the exception occurs again immediately upon return to
the routine that caused the exception.
FREESCALE
4-120
MC68881/MC68882 USER'S MANUAL
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