/* SIMULATION OF WEIGHTED NEURON
   Author: Robert John Morton YE572246C March 1993 */

#include<stdio.h>
#define	R	32767
#define	RR	65556	// 65534 + 22
#define	NI	77	// number of inputs to the neuron
int	AL;
short	SigTab[1025];

int I[] = {11376, 13425, 17920, 30226, 28763, 18940, 15329,
           11376, 13425, 17920, 30226, 28763, 18940, 15329,
           11376, 13425, 17920, 30226, 28763, 18940, 15329,
           11376, 13425, 17920, 30226, 28763, 18940, 15329,
           11376, 13425, 17920, 30226, 28763, 18940, 15329,
           11376, 13425, 17920, 30226, 28763, 18940, 15329,
           11376, 13425, 17920, 30226, 28763, 18940, 15329,
           11376, 13425, 17920, 30226, 28763, 18940, 15329,
           11376, 13425, 17920, 30226, 28763, 18940, 15329,
           11376, 13425, 17920, 30226, 28763, 18940, 15329,
           11376, 13425, 17920, 30226, 28763, 18940, 15329 }; //inputs

int W[] = {12345, 21345, 31245, 16730, 31662, 25460, 13557,
           12345, 21345, 31245, 16730, 31662, 25460, 13557,
           12345, 21345, 31245, 16730, 31662, 25460, 13557,
           12345, 21345, 31245, 16730, 31662, 25460, 13557,
           12345, 21345, 31245, 16730, 31662, 25460, 13557,
           12345, 21345, 31245, 16730, 31662, 25460, 13557,
           12345, 21345, 31245, 16730, 31662, 25460, 13557,
           12345, 21345, 31245, 16730, 31662, 25460, 13557,
           12345, 21345, 31245, 16730, 31662, 25460, 13557,
           12345, 21345, 31245, 16730, 31662, 25460, 13557,
           12345, 21345, 31245, 16730, 31662, 25460, 13557 }; //weights

void SigGen(void) {
	int	i;
	for (i = 0; i < 1024; i++)

   SigTab[i] = (double)(RR / (1 + exp(-((double)(((long)(i)) << 8))/R)) - R);

	SigTab[1024] = R;
}

int Neuron(int *pi, int *pw, int ni) {
   register i;          //input array index, sigmoid table index
   int 	a, o, s;        //activation level, output, sign
   long	P, Hi, Lo;      //long product, high & low accumulators
   for (Hi = 0, Lo = 0, i = 0; i < ni; i++) {
		P = (long)*(pi + i) * *(pw + i);
		Hi += P >> 16;
		Lo += P & 0xFFFF;
   }
   if ((s = (a = ((Hi << 1) + (Lo >> 15)) / ni)) < 0) 
		a = -a;
   o = *(SigTab + (i = a >> 5));
   o += ((*(SigTab + i + 1) - o) * (a & 0x1F)) >> 5;
   if (s < 0) o = -o;
   AL = a;              //extra line to check activation level
   return(o);
}

main() {
   int     OP;
   SigGen();
   OP = Neuron(I, W, NI);
   printf("Activation Level = %6d\n", AL);
   printf("Neuron Output    = %6d\n", OP);
}