(a) Develop stack machine code equivalents of the following simple programs:
(1) void main () { // print numbers 0 through 10
for (int i = 0; i <= 10; i++) write(i, "\n")
}
(2) void main() { // factorials
int n, f;
read(n);
write(n, "! =");
f = 1;
while (n > 0) {
f = f * n;
n = n - 1;
}
write(f);
}
(3) void main () { // simple array handling
int i = 1;
int[] list = new int[11];
list[0] = 5;
while (i <= 10) {
list[i] = 2 - list[i-1];
i++;
}
}
(b) Consider the following general form of T diagram. Although it uses the letters A through I in the various arms of the Ts, one could draw the diagram with fewer letters. How and why?
┌──────────────────────────┐ ┌──────────────────────────┐
│ │ │ │
│ A ──────────> B │ │ C ───────────> D │
│ │ │ │
└───────┐ ┌───────┴──────────┴───────┐ ┌───────┘
│ │ │ │
│ E │ F ────────> G │ H │
│ │ │ │
└──────────┴───────┐ ┌───────┴──────────┘
│ │
│ I │
│ │
└──────────┘
(c) In the practical sessions you (should) have used the Parva2 translator. This was developed at Rhodes by using a compiler generator program called CoCo to produce its C# source code from a so-called "Attribute Grammar" written in a specification language called Cocol, which you will meet in a few weeks' time. This C# code was then compiled with the C# compiler available for the PC. Draw T-diagrams that describe this development.
┌──────────────────────────┐ ┌──────────────────────────┐ ┌─────────────────────────┐
│ │ │ │ │ │
│ ──────────> │ │ ──────────> │ │ ────────> │
│ │ │ │ │ │
└───────┐ ┌───────┴──────────┴───────┐ ┌───────┴─────────┴───────┐ ┌───────┘
│ │ Coco.exe │ │ │ │
│ Cocol │ Cocol ────────> │ │ ────────> │ │
│ │ │ │ │ │
└──────────┴───────┐ ┌───────┴──────────┴───────┐ ┌───────┴─────────┘
│ │ │ │
│ │ │ │
├──────────┤ ├─────────┤
│ │ │ │
│ │ │ │
└──────────┘ └─────────┘