#include <stdio.h>
#include <sys/types.h>
/* for kbhit() */
#include <sys/time.h>
#include <unistd.h>

#define decprec        78
#define b1prec         127
#define b2prec         256   /* b2prec should be b1prec*2+2 */


/* Function for kbhit() - the gcc way */
/* Only works for the <return> key though... */
int kbhit()
{
    struct timeval wait;
    int ret;
    fd_set readfd;

    FD_ZERO(&readfd);
    FD_SET(0, &readfd);
    wait.tv_sec  = 0;   /* Wait zero seconds */
    wait.tv_usec = 0;

    ret = select(1, &readfd, NULL, NULL, &wait);
    return(ret);
}


void main(int argc, char *argv[])
{
int i, j, k, l, pflag=1, kcount=0, jcount=0;
int d[decprec]; 
int b1[b1prec];
int b2[b2prec];
int bn[b2prec][decprec];
int lp1[b2prec];

/* Initializations */
if (argc > 2) {
    printf("Usage: palin [approximate binary startoff]\n");
    exit();
}
printf("\nHit return at any time to stop...\n");
printf("\nInitializing...\n");
l=-1;
for (i=0; i<b1prec; i++) { b1[i]=0; }
for (i=0; i<b2prec; i++) { b2[i]=0; }
/* Initialize bn & lp1 */
bn[0][0]=1; lp1[0]=1;
for (j=1; j<b2prec; j++) { bn[0][j]=0; }
for (i=1; i<b2prec; i++)
{
        k=i-1;
        for (j=0; j<decprec; j++) { bn[i][j]=bn[k][j]*2; }
        /* Now carry digits */
        j=0; while ((bn[i][j]!=0) || (j<lp1[i-1]))
        {
                k=(int)(bn[i][j]/10);
                bn[i][j+1]+=k;
                bn[i][j]=bn[i][j]-k*10;
        j++; }
        lp1[i]=j;
}
if (argc > 1) {
    j=0;
    for (i=(strlen(argv[1])-1); i>-1; i-=1) {
        if (argv[1][i] == '1') { b1[j]=1; } else { b1[j]=0; }
        j++;
    }
    l=j-1;

    /* Strip leading zeros if any exist */
    j=l;  while ((j>-1) && (b1[j]==0)) { l-=1; j-=1; }

    /* Now subtract 1 from the binary half to counter the first increment */
    i=0; while ((b1[i]==0) && (i < b1prec)) { i++; }
    b1[i]=0;  if (i==l) { l-=1; }
    if (i != b1prec) { for (j=0; j<i; j++) { b1[j]=1; } }
}
printf("Ok:\n");

while (1)     /* Main Loop */
{  
/* Increment b1. */
i=0; while (b1[i]==1) { i++; }
b1[i]=1; 
if (i>l) { l++; }
for (j=0; j<i; j++) { b1[j]=0; }

/* Create b2 binary palindrome #1. */
j=0; for (i=l; i>-1; i-=1) { b2[j]=b1[i]; j++; }
for (i=0; i<=l; i++) { b2[j]=b1[i]; j++; }
         /* j is now the length+1 of b2. (b2[0..j-1]) */

/* Convert b2 to decimal d */
for (i=0; i<decprec; i++) { d[i]=0; }
for (i=0; i<j; i++)
{
        if (b2[i]==1)
        {
                for (k=0; k<lp1[i]; k++)
                { d[k]+=bn[i][k]; }
        }
}
/* Now carry all of the digits to next column. */
i=0; while ((d[i]!=0) || (i<lp1[j-1]))
{
        k=(int)(d[i]/10);
        d[i+1]+=k;
        d[i]=d[i]-k*10;
i++; }    /* i is now the length+1 of d[] */

/* Compare d[] to see if it's a palindrome. If so, printf it. */
k=0;
for (j=0; j<i; j++)
{
        if (d[j]!=d[i-1-j]) k=1;
}
if (k==0) 
{
        if (!pflag) { printf("\n");  pflag=1; }
        for (j=(l*2+1); j>-1; j-=1) { printf("%d", b2[j]); }
        i-=1; printf("     ");
        for (j=i; j>-1; j-=1) { printf("%d", d[j]); }
        printf("\n");
}

/* Create b2 binary palindrome #2. */
j=0; for (i=l; i>-1; i-=1) { b2[j]=b1[i]; j++; }
b2[j]=0; j++;
for (i=0; i<=l; i++) { b2[j]=b1[i]; j++; }
         /* j is now the length+1 of b2. (b2[0..j-1]) */

/* Convert b2 to decimal d */
for (i=0; i<decprec; i++) { d[i]=0; }
for (i=0; i<j; i++)
{
        if (b2[i]==1)
        {
                for (k=0; k<lp1[i]; k++)
                { d[k]+=bn[i][k]; }
        }
}
/* Now carry all of the digits to next column. */
i=0; while ((d[i]!=0) || (i<lp1[j-1]))
{
        k=(int)(d[i]/10);
        d[i+1]+=k;
        d[i]=d[i]-k*10;
i++; }    /* i is now the length+1 of d[] */

/* Compare d[] to see if it's a palindrome. If so, printf it. */
k=0;
for (j=0; j<i; j++)
{
        if (d[j]!=d[i-1-j]) k=1;
}
if (k==0) 
{
        if (!pflag) { printf("\n");  pflag=1; }
        for (j=(l*2+2); j>-1; j-=1) { printf("%d", b2[j]); }
        i-=1; printf("     ");
        for (j=i; j>-1; j-=1) { printf("%d", d[j]); }
        printf("\n");
}

/* Create b2 binary palindrome #3. */
j=0; for (i=l; i>-1; i-=1) { b2[j]=b1[i]; j++; }
b2[j]=1; j++;
for (i=0; i<=l; i++) { b2[j]=b1[i]; j++; }
         /* j is now the length+1 of b2. (b2[0..j-1]) */

/* Convert b2 to decimal d */
for (i=0; i<decprec; i++) { d[i]=0; }
for (i=0; i<j; i++)
{
        if (b2[i]==1)
        {
                for (k=0; k<lp1[i]; k++)
                { d[k]+=bn[i][k]; }
        }
}
/* Now carry all of the digits to next column. */
i=0; while ((d[i]!=0) || (i<lp1[j-1]))
{
        k=(int)(d[i]/10);
        d[i+1]+=k;
        d[i]=d[i]-k*10;
i++; }    /* i is now the length+1 of d[] */

/* Compare d[] to see if it's a palindrome. If so, printf it. */
k=0;
for (j=0; j<i; j++)
{
        if (d[j]!=d[i-1-j]) k=1;
}
if (k==0) 
{
        if (!pflag) { printf("\n");  pflag=1; }
        for (j=(l*2+2); j>-1; j-=1) { printf("%d", b2[j]); }
        i-=1; printf("     ");
        for (j=i; j>-1; j-=1) { printf("%d", d[j]); }
        printf("\n");
}

kcount++;
if (kcount==1024) {     /* every 1024 loops check to see if kbhit */
    kcount=0;  jcount++;
    if (kbhit()) {
	printf("\n\nBinary half currently worked with:\n\n");
	for (j=l; j>-1; j-=1) { printf("%d", b1[j]); }
	printf("\n\n");
	exit();
    }
    if (jcount==16384) {  /* every 16777216 loops print current binary half */
	jcount=0;
	if (pflag) { printf("\n");  pflag=0; }
	for (j=l; j>-1; j-=1) { printf("%d", b1[j]); }
	printf("\n");
    }
}

}       /* End of while(1) loop */

}