EXCEPTION PROCESSING STATE (INTERRUPT PROCESSING)
MOTOROLA
PROCESSING STATES
7 - 21
There are two cases in which the stacked address will not point to the illegal instruction:
1. If the illegal instruction is one of the two instructions at an interrupt vector loca-
tion and is fetched during a regular interrupt service, the processor will stack
the address of the next sequential instruction in the normal instruction flow (the
regular return address of the interrupt routine that had the illegal opcode in its
vector).
2. If the illegal instruction follows an REP instruction (see Figure 7-6), the proces-
sor will effectively execute the illegal instruction as a repeated NOP and the
interrupt vector will then be inserted in the pipeline. The next instruction will be
fetched but will not be decoded or executed. The processor will stack the
address of the next sequential instruction, which is two instructions after the
illegal instruction.
In DO loops, if the illegal instruction is in the loop address (LA) location and the instruc-
tion preceding it (i.e., at LA-1) is being interrupted, the loop counter (LC) will be decre-
mented as if the loop had reached the LA instruction. When the interrupt service ends
and the instruction flow returns to the loop, the illegal instruction will be refetched (since
it is the next sequential instruction in the flow). The loop state machine will again decre-
ment LC because the LA instruction is being executed. At this point, the illegal instruction
will trigger the III. The result is that the loop state machine decrements LC twice in one
loop due to the presence of the illegal opcode at the LA location.
INTERRUPT CONTROL CYCLE 1
i
INTERRUPT CONTROL CYCLE 2
i
FETCH
n1
n2
n3
n4
n5
n6
n7
—
—
—
ii1
ii2
n8
DECODE
n1
n2
n3
n4
REP
II
—
—
—
—
ii1
ii2
n8
EXECUTE
n1
n2
n3
n4
REP
REP
NOP
—
—
—
ii1
ii2
n8
INSTRUCTION CYCLE COUNT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
i
= INTERRUPT
ii
= INTERRUPT INSTRUCTION WORD
II
= ILLEGAL INSTRUCTION
n
= NORMAL INSTRUCTION WORD
ILLEGAL INSTRUCTION INTERRUPT
RECOGNIZED AS PENDING
Figure 7-6 Repeated Illegal Instruction
Содержание DSP56K
Страница 12: ...xii LIST of TABLES MOTOROLA List of Tables Continued Table Page Number Title Number ...
Страница 13: ...MOTOROLA DSP56K FAMILY INTRODUCTION 1 1 SECTION 1 DSP56K FAMILY INTRODUCTION ...
Страница 25: ...MOTOROLA DSP56K CENTRAL ARCHITECTURE OVERVIEW 2 1 SECTION 2 DSP56K CENTRAL ARCHITECTURE OVERVIEW ...
Страница 31: ...MOTOROLA DATA ARITHMETIC LOGIC UNIT 3 1 SECTION 3 DATA ARITHMETIC LOGIC UNIT ...
Страница 50: ...DATA ALU SUMMARY 3 20 DATA ARITHMETIC LOGIC UNIT MOTOROLA ...
Страница 51: ...MOTOROLA ADDRESS GENERATION UNIT 4 1 SECTION 4 ADDRESS GENERATION UNIT ...
Страница 77: ...MOTOROLA PROGRAM CONTROL UNIT 5 1 SECTION 5 PROGRAM CONTROL UNIT ...
Страница 124: ...INSTRUCTION GROUPS 6 30 INSTRUCTION SET INTRODUCTION MOTOROLA ...
Страница 125: ...MOTOROLA PROCESSING STATES 7 1 SECTION 7 PROCESSING STATES STOP WAIT EXCEPTION NORMAL RESET ...
Страница 167: ...STOP PROCESSING STATE MOTOROLA PROCESSING STATES 7 43 ...
Страница 168: ...STOP PROCESSING STATE 7 44 PROCESSING STATES MOTOROLA ...
Страница 169: ...MOTOROLA PORT A 8 1 SECTION 8 PORT A ...
Страница 176: ...PORT A INTERFACE 8 8 PORT A MOTOROLA ...
Страница 177: ...MOTOROLA PLL CLOCK OSCILLATOR 9 1 SECTION 9 PLL CLOCK OSCILLATOR x x d Φ VCO ...
Страница 191: ...10 2 ON CHIP EMULATION OnCE MOTOROLA SECTION 10 ON CHIP EMULATION OnCE ...
Страница 218: ...USING THE OnCE MOTOROLA ON CHIP EMULATION OnCE 10 29 ...
Страница 604: ...INSTRUCTION ENCODING A 338 INSTRUCTION SET DETAILS MOTOROLA ...
Страница 605: ...MOTOROLA BENCHMARK PROGRAMS B 1 APPENDIX B BENCHMARK PROGRAMS T T T T T P1 P3 P2 P4 T T T ...
Страница 606: ...SECTION CONTENTS B 2 BENCHMARK PROGRAMS MOTOROLA SECTION B 1 INTRODUCTION 3 SECTION B 2 BENCHMARK PROGRAMS 3 ...
Страница 609: ...BENCHMARK PROGRAMS MOTOROLA BENCHMARK PROGRAMS B 5 ...
Страница 611: ...BENCHMARK PROGRAMS MOTOROLA BENCHMARK PROGRAMS B 7 ...
Страница 613: ...BENCHMARK PROGRAMS MOTOROLA BENCHMARK PROGRAMS B 9 ...
Страница 615: ...BENCHMARK PROGRAMS MOTOROLA BENCHMARK PROGRAMS B 11 ...