implement the "internal" builtin environment #940
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NOTE: this patch touches compiler/parser/, so you obviously need
"cd compiler/parser; make" before "make" to build the compiler.
This patch adds the new keyword `internal` which returns the builtin
environment with 2 primitives (so far):
1. id(sig) - sig->serial()
2. rate(sig) - getSigOrder(sig)
Note that they compute the returned value at compile time.
//-------------------------------------------------------------------
rate(sig) - returns the computability
Example:
process = sin(1), ma.SR/2, nentry("",0,0,10,1), ba.time
: par(i,4,internal.rate);
outputs
output0[i0] = FAUSTFLOAT(0); // compile time const
output1[i0] = FAUSTFLOAT(1); // run time const
output2[i0] = FAUSTFLOAT(2); // block
output3[i0] = FAUSTFLOAT(3); // sample
//-------------------------------------------------------------------
id(sig) - returns the unique signal id. If the compiler can detect that
sig1 and sig2 are "equal", id(sig1) == id(sig2).
Example. Suppose we have
a = +(1);
s = -(1);
as = a : s;
sa = s : a;
id = internal.id;
Now,
process = _ <: id, id(as), id(sa);
or
process = _ <: _, as, sa : par(i,3,id);
outputs
output0[i0] = FAUSTFLOAT(241);
output1[i0] = FAUSTFLOAT(241);
output2[i0] = FAUSTFLOAT(241);
Another example:
process = _ <: id(as-sa), id(0);
outputs
output0[i0] = FAUSTFLOAT(8);
output1[i0] = FAUSTFLOAT(8);
//-------------------------------------------------------------------
Now a bit more useful example:
isZero = internal.id(float) == internal.id(0.0);
returns 1 if the input is compile time constant == 0 or 0.0,
otherwise 0. Afaics, it is not possible to implement such a
helper in faust.
This comes in a separate patch to a) show that it is very easy to add the new primitives, and b) add some documentation. So the new lo/hi primitives act as undocumented lowest/highest but actually work. Say, both process = lowest; and process = internal.lo; output output0[i0] = FAUSTFLOAT(-1.0f); But, say, process = +(1) : lowest; crashes the compiler, while process = +(1) : internal.lo; correctly outputs output0[i0] = FAUSTFLOAT(0.0f); (I guess the implementation of lowest/highest is not finished, with this patch this code can be removed). //------------------------------------------------------------ Example: ge(x,y) = internal.lo(x) >= internal.hi(y); returns 1 if the compiler can deduce at compile time that x >= y, otherwise 0. So process = _,_ <: _,_, +(1),-(1) : ge,ge; does not generate any code and outputs output0[i0] = FAUSTFLOAT(0); output1[i0] = FAUSTFLOAT(1); Again, I don't think it is possible to implement this in faust.
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