/* NAME
 *     fib.c
 *
 *     From the Illustra User Guide, p. 10-14.
 *
 * BUILD INSTRUCTIONS
 *
 *     OSF1:     cc -I$MI_HOME/h -c fib.c
 *               ld -shared -expect_unresolved '*' -o fib.so fib.o
 *
 *     Solaris:  cc -I$MI_HOME/h -c -K PIC fib.c
 *               ld -dy -G -o fib.so fib.o
 *
 *     SUN OS:   cc -I$MI_HOME/h -c -PIC fib.c
 *               ld -o fib.so fib.o
 *
 *     chmod a+x fib.so
 *
 * DATABASE CREATE
 *
 *     create function fib (integer) returns setof(integer)
 *        as external name '/FULL_PATH/fib.so' language C;
 *
 * SAMPLE USAGE
 *
 *     * begin transaction;
 *     + return fib(5);
 *     ---------------
 *     |fib          |
 *     ---------------
 *     |fib_1_1_0    |
 *     ---------------
 *     one row selected
 *     
 *     + fetch from fib_1_1_0 all;
 *     ---------------
 *     |integer      |
 *     ---------------
 *     |0            |
 *     |1            |
 *     |1            |
 *     |2            |
 *     |3            |
 *     |5            |
 *     ---------------
 *     6 rows fetched
 *     + end transaction;
 *
 * $Header: /usr/local/devel/montage/samples/functions/RCS/fib.c,v 1.1 1994/10/06 16:27:30 jta Exp $
 */

#include "mi.h"

typedef struct fibstate {
     int   fib_prec1;
     int   fib_prec2;
     int   fib_ncomputed;
     int   fib_stopval;
} FibState;

int
fib(stopVal, fParam)
int        stopVal;
MI_FPARAM  *fParam;
{
     FibState  *fibState;
     int       next;

     switch(MI_FP_REQUEST(fParam))
     {
          case SET_INIT:
               fibState = (FibState *) mi_alloc(sizeof(FibState));
               MI_FP_SETFUNCSTATE(fParam, (void *) fibState);
               mi_set_mem_duration(fibState, PER_COMMAND);
               if(MI_FP_ARGISNULL(fParam, 0) || stopVal < 0) {
                    MI_FP_SETRETURNISNULL(fParam, MI_TRUE);
                    break;
               }
               if(stopVal < 1) {
                    fibState->fib_prec1 = 0;
                    fibState->fib_prec2 = 1;
                    fibState->fib_ncomputed = 1;
                    fibState->fib_stopval = stopVal;
               }
               else {
                    fibState->fib_prec1 = 0;
                    fibState->fib_prec2 = 1;
                    fibState->fib_ncomputed = 0;
                    fibState->fib_stopval = stopVal;
               }
               break;
          case SET_RETONE:
               fibState = (FibState *) MI_FP_FUNCSTATE(fParam);
               if (fibState->fib_ncomputed < 2) {
                    return ((fibState->fib_ncomputed++ == 0) ? 0 : 1);
               }
               next = fibState->fib_prec1 + fibState->fib_prec2;
               if (next > fibState->fib_stopval) {
                    MI_FP_SETISDONE(fParam, MI_TRUE);
                    return 0;
               }
               if (next == 0) {
                    fibState->fib_prec1 = 0;
                    fibState->fib_prec2 = 1;
               }
               else {
                    fibState->fib_prec1 = fibState->fib_prec2;
                    fibState->fib_prec2 = next;
               }
               return(next);
          case SET_END:
               fibState = (FibState *) MI_FP_FUNCSTATE(fParam);
               mi_free(fibState);
               break;
     }
}