Core Control Registers

 

 

 

 

 

 

 

 

Table 3-2. EMR Description (Continued)

 

 

 

 

 

 

 

Name

Description

Settings

 

 

 

 

 

 

 

 

 

 

 

 

ILST

Illegal Execution Set — Indicates whether an

0 = No execution set rule violated

 

 

Bit 1

execution set grouping rule has been violated (for

1 = Execution set rule violated

 

 

 

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.

 

 

 

 

 

 

 

 

ILIN

Illegal Instruction — Indicates that one or more

0 = No instruction set violation

 

 

Bit 0

of the instruction opcodes received from program

1 = One or more opcodes received are not part of

 

 

 

memory are not in the SC140 instruction set.

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.

 

 

 

 

 

 

 

SC140 DSP Core Reference Manual

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Image 109
Freescale Semiconductor SC140 specifications Ilst, Illegal Execution Set Indicates whether an