Excalibur electronic A-MNL-NIOSPROG-01.1 用户手册

Altera Corporation

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Contents

How to Contact Altera ................................................................................................................... iv
Typographic Conventions ...............................................................................................................v

Overview...............................................................................................1

Introduction .......................................................................................................................................1

Audience ....................................................................................................................................1

Nios CPU Overview .........................................................................................................................1
Instruction Set ...................................................................................................................................2
Register Overview ............................................................................................................................2

General-Purpose Registers ......................................................................................................2
The K Register ...........................................................................................................................4
The Program Counter...............................................................................................................4
Control Registers.......................................................................................................................4

Memory Access Overview...............................................................................................................7

Reading from Memory (or Peripherals) ........................................................................8
Writing to Memory (or Peripherals) ..............................................................................9

Addressing Modes..........................................................................................................................10

5/16-bit Immediate Value .....................................................................................................10
Full Width Register-Indirect..................................................................................................12
Partial Width Register-Indirect .............................................................................................12
Full Width Register-Indirect with Offset.............................................................................13
Partial Width Register-Indirect with Offset ........................................................................13

Program-Flow Control ...................................................................................................................14

Relative-Branch Instructions .................................................................................................14
Absolute-Jump Instructions ..................................................................................................15
Trap Instructions.....................................................................................................................15
Conditional Instructions ........................................................................................................15

Exceptions ........................................................................................................................................16

Exception Handling Overview .............................................................................................16
Exception Vector Table ..........................................................................................................16
External Hardware Interrupt Sources..................................................................................17
Internal Exception Sources ....................................................................................................17

Register Window Underflow ........................................................................................17
Register Window Overflow...........................................................................................18

Direct Software Exceptions (TRAP Instructions) ...............................................................19
Exception Processing Sequence ............................................................................................ 19

Register Window Usage.................................................................................................20
Status Preservation: ISTATUS Register .......................................................................20

Return-Address .......................................................................................................................21
Simple and Complex Exception Handlers ..........................................................................21

Altera Corporation

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Contents