127 lines
3.4 KiB
C
127 lines
3.4 KiB
C
/* #!/usr/local/bin/otcc */
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/*
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* Sample OTCC C example. You can uncomment the first line and install
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* otcc in /usr/local/bin to make otcc scripts !
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*/
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/* Any preprocessor directive except #define are ignored. We put this
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include so that a standard C compiler can compile this code too. */
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#include <stdio.h>
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/* defines are handled, but macro arguments cannot be given. No
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recursive defines are tolerated */
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#define DEFAULT_BASE 10
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/*
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* Only old style K&R prototypes are parsed. Only int arguments are
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* allowed (implicit types).
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*
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* By benchmarking the execution time of this function (for example
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* for fib(35)), you'll notice that OTCC is quite fast because it
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* generates native i386 machine code.
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*/
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fib(n)
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{
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if (n <= 2)
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return 1;
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else
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return fib(n-1) + fib(n-2);
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}
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/* Identifiers are parsed the same way as C: begins with letter or
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'_', and then letters, '_' or digits */
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fact(n)
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{
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/* local variables can be declared. Only 'int' type is supported */
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int i, r;
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r = 1;
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/* 'while' and 'for' loops are supported */
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for(i=2;i<=n;i++)
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r = r * i;
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return r;
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}
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/* Well, we could use printf, but it would be too easy */
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print_num(n, b)
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{
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int tab, p, c;
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/* Numbers can be entered in decimal, hexadecimal ('0x' prefix) and
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octal ('0' prefix) */
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/* more complex programs use malloc */
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tab = malloc(0x100);
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p = tab;
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while (1) {
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c = n % b;
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/* Character constants can be used */
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if (c >= 10)
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c = c + 'a' - 10;
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else
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c = c + '0';
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*(char *)p = c;
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p++;
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n = n / b;
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/* 'break' is supported */
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if (n == 0)
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break;
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}
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while (p != tab) {
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p--;
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printf("%c", *(char *)p);
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}
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free(tab);
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}
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/* 'main' takes standard 'argc' and 'argv' parameters */
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main(argc, argv)
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{
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/* no local name space is supported, but local variables ARE
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supported. As long as you do not use a globally defined
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variable name as local variable (which is a bad habbit), you
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won't have any problem */
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int s, n, f, base;
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/* && and || operator have the same semantics as C (left to right
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evaluation and early exit) */
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if (argc != 2 && argc != 3) {
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/* '*' operator is supported with explicit casting to 'int *',
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'char *' or 'int (*)()' (function pointer). Of course, 'int'
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are supposed to be used as pointers too. */
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s = *(int *)argv;
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help(s);
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return 1;
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}
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/* Any libc function can be used because OTCC uses dynamic linking */
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n = atoi(*(int *)(argv + 4));
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base = DEFAULT_BASE;
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if (argc >= 3) {
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base = atoi(*(int *)(argv + 8));
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if (base < 2 || base > 36) {
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/* external variables can be used too (here: 'stderr') */
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fprintf(stderr, "Invalid base\n");
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return 1;
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}
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}
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printf("fib(%d) = ", n);
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print_num(fib(n), base);
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printf("\n");
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printf("fact(%d) = ", n);
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if (n > 12) {
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printf("Overflow");
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} else {
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/* why not using a function pointer ? */
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f = &fact;
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print_num((*(int (*)())f)(n), base);
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}
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printf("\n");
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return 0;
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}
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/* functions can be used before being defined */
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help(name)
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{
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printf("usage: %s n [base]\n", name);
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printf("Compute fib(n) and fact(n) and output the result in base 'base'\n");
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}
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