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language:controlflow [2020/06/03 14:21]
rajit [Selections]
language:controlflow [2022/07/17 08:07]
rajit [Loops]
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 An example of the loop construct in ACT is shown below: An example of the loop construct in ACT is shown below:
  
-<code>+<code act>
 ( i : 10 : bool x[i..i]; ) ( i : 10 : bool x[i..i]; )
 </code> </code>
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 range ''0..9''. The body of the loop is the statement ''bool x[i..i];''. The effect of this statement is the same as range ''0..9''. The body of the loop is the statement ''bool x[i..i];''. The effect of this statement is the same as
  
-<code>+<code act>
 bool x[0..0]; bool x[0..0];
 bool x[1..1]; bool x[1..1];
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 is shown below: is shown below:
  
-<code>+<code act>
 register r[1..8]; register r[1..8];
 (i : 1..8 : r[i](in[i],out[i],control); ) (i : 1..8 : r[i](in[i],out[i],control); )
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 command language. command language.
  
-<code>+<code act>
 pint i; pint i;
 i=0; i=0;
Line 65: Line 65:
  
 In production rule bodies, the loop In production rule bodies, the loop
-<code>+<code act>
 (&i:3: x[i]) (&i:3: x[i])
 </code> </code>
 expands to expands to
-<code>+<code act>
 x[0] & x[1] & x[2] x[0] & x[1] & x[2]
 </code> </code>
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 syntax). The ''&'' symbol separates the body of the loop that is syntax). The ''&'' symbol separates the body of the loop that is
 instantiated for different values of ''i'' instantiated for different values of ''i''
 +
 +The syntactic replication construct is written as follows:
 +<code act>
 +(sym id : range : body )
 +</code>
 +The ''sym'' (symbol) might be empty. ''id'' is a variable that can be used in ''body'', and takes the range specified by ''range''. ''range'' can be either an integer-valued expression or ''start .. end'' to indicate a start and end index. The result of the replication is
 +<code act>
 + body(id set to lo) sym body(id set to lo+1) sym ... sym body(id set to hi)
 +</code>
 +where ''lo'' is the starting index of the range, and ''hi'' is the ending index, and ''body(id set to x)'' means ''body'' with the value of ''x'' substituted by the constant ''id''.
  
  
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 syntax of a selection statement is: syntax of a selection statement is:
  
-<code>+<code act>
 [ boolean_expression -> body  [ boolean_expression -> body 
 [] boolean_expression -> body [] boolean_expression -> body
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 something special for register 0 as follows: something special for register 0 as follows:
  
-<code>+<code act>
 (i : 32 :  (i : 32 : 
     [ i = 0 -> r0(in[i],out[i],control);     [ i = 0 -> r0(in[i],out[i],control);
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 definition can be used to create a tree structure. definition can be used to create a tree structure.
  
-<code>+<code act>
 template<pint N> template<pint N>
 defproc tree (bool a[N]) defproc tree (bool a[N])
 { {
-  [ N = 1 -> leaf l(a[0]) +  [ N = 1 -> leaf l(a[0]);
  [] N > 1 -> tree<N/2> t0(a[0..N/2-1]);  [] N > 1 -> tree<N/2> t0(a[0..N/2-1]);
-             tree<N-N/2> t1(a[N/2..N-1])+             tree<N-N/2> t1(a[N/2..N-1]);
   ]   ]
 } }