Freescale Semiconductor StarCore SC140 - Manual (Page 109)

Core Control Registers
SC140 DSP Core Reference Manual 3-9
ILST
Bit 1 Illegal Execution Set — Indicates whether an
execution set grouping rule has been violated (for
example, more than one opcode dispatched to an
execution unit). The ILST bit is a sticky bit. The bit
is set if the appropriate exception occurred, and it
can only be cleared by the programmer. The
clearing operation should only be performed
during the illegal exception service routine. This
bit is cleared by writing back 1 to it as explained in
Section 3.1.2.1, “Clearing EMR Bits.”
Whenever an illegal set is detected, an illegal
exception is generated. The conditions that set
this bit when violated are listed in
Section 5.8.5.1.2, “Illegal Execution Set.”
ILST is cleared at reset.
0 = No execution set rule violated
1 = Execution set rule violated
ILIN
Bit 0 Illegal Instruction — Indicates that one or more
of the instruction opcodes received from program
memory are not in the SC140 instruction set.
“Holes” in operand tables are detected as illegal.
Both opcodes for instructions considered reserved
and holes in operand tables are determined to be
illegal. Whenever an illegal instruction is detected,
an illegal exception is generated.
The ILIN bit is a sticky bit. It is set if the
appropriate exception occurred, and can only be
cleared by the user. The bit is cleared by writing
back 1 to it, as explained in
Section 3.1.2.1,
“Clearing EMR Bits.” This clearing operation
should only be performed during the illegal
exception service routine.
ILIN is cleared at reset.
0 = No instruction set violation
1 = One or more opcodes received are not part of
the SC140 instruction set
Table 3-2. EMR Description (Continued)
Name Description Settings