Unbounded loop

[zhuanhao-wu]

There are several places where the generated loops are unbounded according to Vivado, listed as follows, although they might be bounded.

Loop 1

sc_uint<log2rz(4)+1>tgtreg;
for(tgtreg=0; srcreg<4; srcreg++,tgtreg++)
{
    if(!pb_c[srcreg].f)	break;
    else				tmp[tgtreg]=pb_c[srcreg];
}

Loop 2

while(n < fpblk_sz(DIM))
{
	//looking for 0's in a unary substring  INNER LOOP IN ZFP
	if(state&FOUND_1)
	{
		if(state&FIRST_0)			//account for the first 1 seen in the unary substring using the "bits" state variable.
			{state=S2;if(n < fpblk_sz(DIM))bits--;}

		if(n < fpblk_sz(DIM) - 1 && !(state&FOUND_0S))	//Find length of '0's substring. terminate (go->S3) if a '1' is found.
		{
			if((!bits) || (!bits--))			//if bits cannot still be decoded..
				{x[n]=true; state=S3;}			//tally the last bit positively identified and terminate (go->S3).
			else								//however if bits can still be decoded...
			{
				if(stream_window[bitoff++])		//check if '0' is in the current string position
					{x[n]=true; state=S3;} 	//a 1 was found, signifying end of substring (go->S3)
			}
			n++;	//consider next bit in the plane to be decoded
		}

		//accounts for the case when no more 0's could possibly fit in the main string, but substring not explicitly terminated.
		if((n==fpblk_sz(DIM)-1) || (state&FOUND_0S))
		{
			if((n >= fpblk_sz(DIM)-1) && !(state&FOUND_0S))
				{x[n]=true; n++;}			  //force substring end
			state=S3;						  //force substring termination (go->S3)
		}
	}

	//looking for 1's in a unary substring. OUTER LOOP IN ZFP
	if(!(state&FOUND_1))
	{
		if(!bits || (n>=fpblk_sz(DIM)))	//nothing left to search through...
			break;				//exit the unary decoder state machine.
		//account for n = size case? what should happen is that n gets incremented to size and you break here before doing the stuff below.
		if(stream_window[bitoff++])			//A unary substring was found, next find all '0''s after this '1' in the string.
			state=S1;
		else break;	//stop looking for valid unary strings. This is the same as going to S0.
	}

}

Loop 3
(An alternative to this might be an explicit priority decoder.)

ui_t e = 0;
while (rn >> (e + 1))
	e++;

However, these loops might be transformed/rewritten if a constant bound is known, with the following form:

int i;
for(i = 0; i < BOUND; i++) {
  if(original_terminate_condition) break;
  else {
    // original_loop_body; potentially with breaks;
    // increment_to_loop_variable;
  }
}

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