//
// TT CTOV Illux example test suite.
//
// This C source file contains examples from the manual.
//
// These examples can be run using the makefile provided.  The output is provided in objdir.
//
#include "cxctypes.h"


// E1. A combinatorial function: inverter

  void e1(u1 *op, u1 i) { *op = !i;  }

  void e1a(u1 *o, u1 i) { *o = !i;  }

//
// The difference between E1 and E1A is the text name of the output variable.  E1A does not
// obey the default naming policy for outputs, and so "_actual" appears in the generated file.
// Note that clk and cx_reset are added even to combinatorial modules.
//

//--------------------------------------------------------------------------------------------
// E2. A simple 3 bit counter

  void e2a(u1 clk, u1 cx_reset, u3 *outp) { *outp = *outp + 1; cx_barrier(); } 

// Here the thread exits but the output signal is updated before the barrier
// with no updates afterwards.  According to Tenos rules, this generates a registered 
// function.  This design does not work though, since there is no actual register
// to hold the count value in the C code. We modifiy it as follows

  void e2b(u1 clk, u1 cx_reset, u3 *outp) { static u3 reg; reg += 1; *outp = reg; cx_barrier(); } 


// We can add reset as follows, taking advantage of the static delcaration of reg where the
// value assigned will only be stored when cx_reset is true:

  void e2c(u1 clk, u1 cx_reset, u3 *outp) { static u3 reg = 0; reg += 1; *outp = reg; cx_barrier(); } 


// Of course, we could also add an explicit reset using a conditional expression if
// desired, as shown in e2d

  void e2d(u1 clk, u1 cx_reset, u3 *outp) { static u3 reg; reg = (cx_reset) ? 0: reg +1; *outp = reg; cx_barrier(); } 

// Or with an if statement
  void e2e(u1 clk, u1 cx_reset, u3 *outp) { static u3 reg; if (cx_reset) reg = 0; else reg++; *outp = reg; cx_barrier(); } 

// The variations in the object files generated by these examples show that output optimisation
// is not very good in the current CTOV release.  However, the subsequent Verilog tools will
// optimise and thus remove the variations.

//--------------------------------------------------------------------------------------------
// E3. Another 3 bit counter, using the process loop Tenos semantic

  void e3(u1 clk, u1 cx_reset, u3 *outp) 
    { u3 reg = 4;
      while(1) { reg += 1; *outp = reg; cx_barrier(); }  
    }


// Here the thread does not exit, but the function is just the same as
// E2.  Note that the call to cx_barrier() is needed inside the body of
// the loop and the compiler will put one in automatically if it is
// missing.  This action can be seen in the report file.  The exception
// is when compile time unroll of the loop is specified (TODO say how),
// but compile time unroll of an infinite loop is not possible.


//--------------------------------------------------------------------------------------------
// E4. Another 3 bit counter

  void e4(u1 clk, u1 cx_reset, u3 *outp) 
 	{ u3 reg;
	  while(1) 
	    {
	      reg ++; *outp = reg; cx_barrier(); 
	      reg ++; *outp = reg; cx_barrier(); }
	}

// This produces the same behaviour as E2 and E3, but the compiler may not
// always optimise away the statereg variable which it generates to
// represent which barrier statement is current.


//--------------------------------------------------------------------------------------------
// E5. An output that depends on state and is updated after the last barrier

// Here the thread exits, thus enabling combinatorial outputs to be
// produced, but we also have some state.

  void e5(u1 clk, u1 cx_reset, u1 x, u1 c, u1 *yp) 
   {
     static u3 reg;
     reg = reg + c;
     cx_barrier();
     *yp = x ^ (reg & 1);  // combinatorial route from x to y.
   }
//--------------------------------------------------------------------------------------------
     // Examples Using Memories
     

     // M1.  Simple RAM access

     // Define an array with more locations than "minarraysize" and it 
     // will automatically be converted to a single-ported synchronous
     // RAM memory.
#ifdef REGRESSION_MEMS
  u5 mem[10000];
#endif
  void m1(u1 clk, u1 cx_reset, u1 x, u1 *yp) 
  {
     mem[100+x] = mem[105-x];
     *yp = mem[22];
     cx_barrier();
  }



// End of TT regression.c