FSM derivation From SystemC

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FSM derivation From SystemC
Vikram Singh Saun 2002MCS032
Supervisor Dr. Preeti Ranjan Panda
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Objective

• Input A SystemC description (SC_THREAD /
  SC_CTHREAD) with wait() statements inside
  arbitrarily complex control structures.
• Output FSM showing control flow and SC_METHOD.

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Outline

• Project Flow
• Overview of Algorithm
• Changes in Algorithm
• Verification
• SystemC Compiler
• Rules for Manual Conversion
• Changes in suif2c

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Project Flow
SystemC Specification with SC_THREAD/SC_CTHREAD
manual
SystemC to C
C to SUIF2
SUIF2 to FSM
SC_METHOD Generation ( FSM to SUIF2 )
Display FSM
SUIF2 to C
FSM in DOT and VCG format
C to SystemC
SystemC Specification with SC_METHOD
manual
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Suif 2 FSM
SUIF2
Scope Flattening Pass
For Loop to While Loop
Do-While Loop to While Loop
wait_untill to while-wait
Algorithm
Compact FSM
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Restrictions on User

• There must be at least one wait() in every
  execution path within a loop,otherwise FSM can
  not be derived.

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Outline

• Project Flow
• Overview of Algorithm
• Changes in Algorithm
• Verification
• SystemC Compiler
• Rules for Manual Conversion
• Changes in suif2c

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Algorithm (structure)
main
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PATH

• So a PATH is record of statements between two
  states( wait()s ) in execution path.
• all functions handle_while, handle_switch and
  handle_if are taking a list of PATHs in input
  and returning the same.

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Algorithm (logic)

• statement will be appended to statement list.

• One PATH after wait.

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Algorithm(logic) Contd..

• There are some PATH in input from states before
  construct.

• Some PATH in output from states at last of each
  execution path within construct.

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Outline

• Project Flow
• Overview of Algorithm
• Changes in Algorithm
• Verification
• SystemC Compiler
• Rules for Manual Conversion
• Changes in suif2c

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Changes In Algorithm

• A new Structure Introduced for reducing
  redundancy of statements among Paths.

A
A
A,B
A,C
B
C
C
B
(OLD)
(NEW)
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Changes In Algorithm(Cont..)

• In loops if loop executes at least once then
  dont generate path when loop condition is false.

For(i0ilt10i)
i 0 while(ilt10) i
ilt10
!(ilt10)
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Changes In Algorithm(Cont..)

• Scope Flattening Pass

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Outline

• Project Flow
• Overview of Algorithm
• Changes in Algorithm
• Verification
• SystemC Compiler
• Rules for Manual Conversion
• Changes in suif2c

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Verification

• Simulate both SC_THREAD and SC_METHOD, results
  must be same.
• Output In each cycle should be same for both
  cases.
• Write Output to file then compare files of both
  cases.

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Verification(Examples)

• 1.Factorial(25 lines)
• source/extra/synopsys/syn/doc/syn/ccsc/ccsc_examp
  les
• 2. complex number multiplication(36 lines)
• 3. memory controller(46 lines)
• 4. memory controller with while loop in
  initialization.
• sourceUser's Guide of SystemC 2.0
• 5. Traffic Light Controller(65 lines)
• 6. Bus controller(30)
• 7. Counter(10 lines)
• source /usr/local/systemc-2.0/examples/systemc/
• 8. fetch unit of risc_cpu(200 lines)
• 9. decode unit of risc_cpu(130 lines)
• 10. execute unit of risc_cpu(800 lines)

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Outline

• Project Flow
• Overview of Algorithm
• Changes in Algorithm
• Verification
• SystemC Compiler
• Rules for Manual Conversion
• Changes in suif2c

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SystemC compiler

• It Synthesizes a SystemC description with a
  behavioral module, RTL modules or a mixed
  RTL-behavioral module into an RTL description or
  gate level netlist.
• It Supports SuperState and Cycle Fixed Modes.
• It have some restrictions for both.

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How FSM/SC_METHOD Useful

• SC_METHOD can be input to the SystemC Compiler.
• FSM generation step has no any restrictions like
  SystemC compiler.

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Restrictions of SystemC compiler(for both modes)

• Place atleast one wait in every loop.
• Wait between two writes to same port.
• output.write(a)
• //wait()
• output.write(b)
• Define the reset values and put atleast one wait
  before infinite loop. ( TLC )
• Wait()
• While(true)
• ..

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Restrictions(Cont..)

• Do not include either a conditional branch or a
  loop in the reset behavior.
• fetch(if) and memc with while loop
• output.write( a)
• ..
• if( I 5)
  for(i0ilt10i)
• output.write(a)
  output.write(i)

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Restrictions(Cont..)

• If one branch of if/switch have wait() then every
  branch must have at least one wait.
• fetch, decode (if)
• exec (switch)
• Place at least one wait() after last write inside
  a loop and also before break/continue.
• bus controller.
• Place at least one wait() after last write before
  a loop.
• TLC

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Restrictions(Cycle Fixed)

• Place at least one wait() immediately before
  loop except main loop.
• //wait()
• while(cond)..
• TLC, decode
• Place at least one wait() immediately after each
  loop to exit the level of scheduling hierarchy
  created by loop.

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Outline

• Project Flow
• Overview of Algorithm
• Changes in Algorithm
• Verification
• SystemC Compiler
• Rules for Manual Conversion
• Changes in suif2c

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Rules for Manual Conversion(SystemC?C)

• Input Program SC_THREAD/SC_CTHREAD in input.cc
• Corresponding C program input_thread.c
• Put all i/p ports,o/p ports and other
  declarations from input.cpp as global variables
  in input_thread.c. Change there type to int.
• Ex. sc_in(any type) in_port    int in_port
• Introduce function declaration in global scope
  for all fuctions used in SC_THREAD including
  wait() and wait_until().
• if function returns or takes some parameter in
  input then make type int.

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Rules for Manual Conversion(SystemC?C)(Cont)

• Introduce define true 1 and define false 0 .
• introduce a function main() in input_thread.c and
  copy whole body of sc_thread in input.cc to body
  of main().
• Make all variables in main int.
• If there are some variables declared inside body
  of main() in such a way that is not supported in
  C as
• for(int i 0)
• then declare int i at start of main.
• Replace all cout's by printf's or there may be an
  alternate way of printf("0") etc.

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Rules for Manual Conversion(SystemC?C)(Cont)

• if there is wait(k) then replace it by
•   for(k times) wait()
• Replace a.read() by read(a).
• Replace a.write(b) by write(a,b).
• Replace a.delayed by delayed(a).
• Replace a.range(7,0) in right side by
  range(a,7,0).
• Replace a.range(7,0) b by range(a,7,0,b).

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Rules for Manual Conversion(SystemC?C)(Cont)

• I am not handling gotos.
• if(a b) k if(a) k
• else if(b) k
• 
  
• if(a b) k
• if(a)
• 
  if(b)
• 
  k
•  

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Rules for Manual Conversion(C?SystemC)

• Input C program input_method.c
• corresponding SystemC program input_method.cpp
• Copy class declaration from input.cpp to
  input_method.cpp.
• In that declaration the SC_THREAD/SC_CTHREAD will
  now become SC_METHOD.
• if there is a watching statement associated with
  SC_CTHREAD. for watching(cond), write
• if(cond)
• switch_index 0
• at start of body of sc_method.
•  

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Rules for Manual Conversion(C?SystemC)(cont..)

• Put all static declaration from main() of
  input_method.c in class declaration, remove staic
  and recover there type.
• static int input
• sc_intlt32gt input
• Some temporary variables are also there, write
  their type by their use.
• Put statement switch_index 0 in SC_CTOR of
  class.
• Copy Global declarations introduces for printf's
  in input_method.c as global variables.
• printf(embedded) --gt printf( _arr)

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Rules for Manual Conversion(C?SystemC)(cont..)

• Copy rest body of main()(input_method.c) after
  switch_index 0 statement in SC_METHOD.
• Replace read(a) by a.read().
• write(a,b) by a.write(b).
• delayed(a) by a.delayed().
• range(a,7,0) by a.range(7,0) and range(a,7,0,b)
  by a.range(7,0) b
• If suggested method for cout used then do inverse
  processing.

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Outline

• Project Flow
• Overview of Algorithm
• Changes in Algorithm
• Verification
• SystemC Compiler
• Rules for Manual Conversion
• Changes in suif2c

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Changes in Suif2c

• Switch(i)
• case 1
• goto label_1
• case 2
• goto label_2
• label_1 . goto label_3
• label_2 .. goto label_3
• label_3

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Thank You