deps/lightning/doc/rfib.c

   1 #include <stdio.h>
   2 #include <lightning.h>
   3
   4 static jit_state_t *_jit;
   5
   6 typedef int (*pifi)(int);       /* Pointer to Int Function of Int */
   7
   8 int main(int argc, char *argv[])
   9 {
  10   pifi       fib;
  11   jit_node_t *label;
  12   jit_node_t *call;
  13   jit_node_t *in;                 /* offset of the argument */
  14   jit_node_t *ref;                /* to patch the forward reference */
  15   jit_node_t *zero;             /* to patch the forward reference */
  16
  17   init_jit(argv[0]);
  18   _jit = jit_new_state();
  19
  20   label = jit_label();
  21         jit_prolog   ();
  22   in =  jit_arg      ();
  23         jit_getarg   (JIT_R0, in);              /* R0 = n */
  24  zero = jit_beqi     (JIT_R0, 0);
  25         jit_movr     (JIT_V0, JIT_R0);          /* V0 = R0 */
  26         jit_movi     (JIT_R0, 1);
  27   ref = jit_blei     (JIT_V0, 2);
  28         jit_subi     (JIT_V1, JIT_V0, 1);       /* V1 = n-1 */
  29         jit_subi     (JIT_V2, JIT_V0, 2);       /* V2 = n-2 */
  30         jit_prepare();
  31           jit_pushargr(JIT_V1);
  32         call = jit_finishi(NULL);
  33         jit_patch_at(call, label);
  34         jit_retval(JIT_V1);                     /* V1 = fib(n-1) */
  35         jit_prepare();
  36           jit_pushargr(JIT_V2);
  37         call = jit_finishi(NULL);
  38         jit_patch_at(call, label);
  39         jit_retval(JIT_R0);                     /* R0 = fib(n-2) */
  40         jit_addr(JIT_R0, JIT_R0, JIT_V1);       /* R0 = R0 + V1 */
  41
  42   jit_patch(ref);                               /* patch jump */
  43   jit_patch(zero);                              /* patch jump */
  44         jit_retr(JIT_R0);
  45
  46   /* call the generated code, passing 32 as an argument */
  47   fib = jit_emit();
  48   jit_clear_state();
  49   printf("fib(%d) = %d\n", 32, fib(32));
  50   jit_destroy_state();
  51   finish_jit();
  52   return 0;
  53 }