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Graduate Institute of Electronics Engineering, NTU NTU/NSC Confidential

2004/6/152004/6/15

A Survey on HW/SW Codesign Representation Models

Final Report

R91943084

R92943088

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Outline Introduction Related Work&Objective Representation Comparison Conclusion

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Introduction Modeling is a very important issue Capture the features of system & describe The system design process that combines the HW/SW

perspectives from the earliest stages to exploit design flexibility and efficient allocation of functions

High-performance & low-cost productions The increase in system complexity and the reduction in

design times

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Outline Introduction Related Work&Objective Representation Comparison Conclusion

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Related Work & Objective The main purpose of goal is to explore the field of

heterogeneous systems. Many computational models have been proposed to

represent digital systems. Encompass a broad range of styles , characteristics

and application domains. Hardware description languages, namely VHDL,

HardwareC, SDL, Statecharts…

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Outline Introduction Related Work& Objective Representation Comparison Conclusion

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Representation Models A variety of models has been developed and used to

represent heterogeneous system In the following we present the main representation

models that have been utilized in codesign Reactive & synchronous

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Finite State Machines The classical FSM representation is the most well-know

model for describing control systems Consists of a set of states, a set of inputs, a set of

outputs, a function which defines the outputs in terms of inputs and states and a next-state function.

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Disadvantages The exponential growth of the number of the states as

the system complexity rises! No hierarchical constructions are allowed In consequence FSMs are not appropriate for modeling

practical systems.

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Other Models Discrete-Event system

The principal disadvantage of discrete-event modeling is its cost

Petri Nets Four basic elements:

A set of places A set of transitions An input function that maps transitions to places An output function

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Other Models Dataflow Graphs

Dataflow process networks is a model of computation to be used in signal processing systems.

Special cases: SDF CSDF

Communicating Processes Synchronous/Reactive Models

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Comparison of Models

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Conclusions Most of them are well suited for data or control-oriented

systems but few representation support widely both. Timing is an important subject in modern electronic

systems, many of the related models do not have an explicit notion of time.

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A Implementation Work based on Intel

8088 microprocessor with FSM

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Intel 8088 Architecture

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Control Unit Modeling

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Control Unit Modeling Feed : An interface between instruction queue and instruction decoder. It fetches instruction one by one

and is controlled by instruction decoder because of unequal length of instruction. Control : Decoding the instructions from memory and translating them into equal length instructions and

puts data and address to register “Memreg. Memreg contains EX, Reg_s, Reg_d1, Reg_d2, memaddr, data1 and data2 Instruction decoder : Decoding the first one or two instruction and deciding the length of instructions. It

fills the field in Reg_s, Reg_d1and Reg_d2. Distributor : Analyzing and placing the instructions into Memaddr, data1 and data2.

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EX register

(10-8) bits move type (000) logic/arithmetic type (001) jump type (010) call/return type (100)

(7-5) from where to where reg->reg (000) reg->ram (001) data(in instruction)->reg(010) data->ram(011) ram->reg(100) data->two reg(101) default(111)

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EX register (4-1)operation(arithmetic and logic type)

add(0000) inc (0001) sub(0010) mul (0011) inv(0100) and (0101) or(0110) xor (0111) shift L(1000) shift R(1001) rotate L(1010) rotate R(1011)

(4-1)operation(jump) jump short (0000) Direct within seg (0001) Indirect within segment (0010) Direct inter-segment (0100) Jump on zero /on equal (1000)

(0) jump from ram (1)

(0) word word (1) byte (0)

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Modeling of the EX register with FSM

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Modeling of the EX register with FSM

if(EX[10:8]==3'b0)begin casex(move) 4'b0: begin //initial of move casex(EX[7:5]) 3'b00x,3'b10,3'b011: move<=4'b1; default: move<=4'b101; endcase end 4'b1: begin //read form register if(EX[7:5]==3'b10 | EX[7:5]==3'b11) sel_r<=3'b1; else if(~reg_s[3])begin//from gen_reg sel_go<=2'b0; addr_gen<=reg_s[2:0]; …………………………………… …………………………………… move<=4'b10; end 4'b10: begin enable<=1'b1; move<=4'b11; end …………………………………….……………………………………

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Arithmetic Logic Unit

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General Register

Data_in: A 16-bit bus for data to come in.

Data_out: A 16-bit bus to send out data. Which: a 3-bit signal to indicate which

register should be accessed. Word : used to specify the data length

comes in (or goes out) is a

byte(8 bits) or a word(16 bits). 8bits registers: AH, AL, BH, BL, CH, CL,

DH, DL

16 bits registers: AX, BX, CX, DX, IP, SP,

BP, SI, DI

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Simulation Result MOVE ( immediate to Reg)

Instruction: 1100_0111_1100_0010_1000_1011_1001_0100 (c7c28b94) Action: DX <= Data

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Simulation Result MOVE ( Reg to Reg)

Instruction: 1000_1011_1100_1010 (8bca) Action: CX <= DX

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Simulation Result Step. 16 SUB (Reg to Reg)

Instruction: 0010_1011_1101_0001 (2bd1)

Action: DX = DX – CX

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Reference “Microcomputer Systems: The 8086/8088 Family

Architecture, Programming, and Design,” Yu-Cheng Liu, Glenn A. Gibson.

“UML-Based Co-Design for Run-Time Recon-gurable Architectures,” Thomas Beierlein, Dominik FrÄohlich, Bernd Steinbach.

“A Model-Based Approach to System-Level Co-Design,” Thomas Beierlein, Dominik FrÄohlich, Bernd Steinbach.

“A Survey on Hardware/Software Codesign Representation Models,” Luis Alejandro Cortés, Petru Eles and Zebo Peng.