/* This file is in the public domain. */

#include <stdarg.h>
#include <string.h>
#include <strings.h>

#include "fnprintf.h"

static unsigned int cvt_num(char *buf, unsigned long int n, const char *dv)
{
 char *bp;
 unsigned int base;
 unsigned int i;
 unsigned int j;

 bp = buf;
 base = strlen(dv);
 do
  { *bp++ = dv[n%base];
    n /= base;
  } while (n > 0);
 n = bp - buf;
 i = 0;
 j = n - 1;
 while (i < j)
  { char t;
    t = buf[i];
    buf[i] = buf[j];
    buf[j] = t;
    i ++;
    j --;
  }
 return(n);
}

int fnprintf(void (*fn)(char), const char *fmt, ...)
{
 va_list ap;
 const char *fp;
 unsigned int flags;
#define F_ALT   0x00000001 /* "alternate form" */
#define F_ZFILL 0x00000002 /* pad with zeroes rather than spaces */
#define F_LEFT  0x00000004 /* justify left rather than right */
#define F_PLUS  0x00000008 /* explicit sign always */
#define F_SPACE 0x00000010 /* space for positive number */
#define F_WIDTH 0x00001000 /* explicit width given */
#define F_DOT   0x00002000 /* width/precision separator seen */
#define F_PREC  0x00004000 /* explicit precision given */
#define F_SHORT 0x00008000 /* short-data flag given */
#define F_LONG  0x00010000 /* long-data flag given */
#define F_NUM   0x02000000 /* doing numeric conversion */
 unsigned int width;
 unsigned int prec;
 unsigned int *dvar;
 char conv;
 unsigned int charcount;
 char tmp[64];
 const char *os;
 const char *altstr;
 int altlen;
 int nsb;
 int nz;
 int noc;
 int nsa;
 int i;

 charcount = 0;
 fp = fmt;
 va_start(ap,fmt);
 while (*fp)
  { if (*fp != '%')
     { if (fn) (*fn)(*fp);
       fp ++;
       charcount ++;
       continue;
     }
    flags = 0;
    width = 0;
    prec = 0;
    dvar = &width;
    conv = 0;
    while (*++fp && !conv)
     { switch (*fp)
	{ case '#':
	     flags |= F_ALT;
	     break;
	  case '-':
	     flags |= F_LEFT;
	     break;
	  case '+':
	     flags |= F_PLUS;
	     break;
	  case ' ':
	     flags |= F_SPACE;
	     break;
	  case '0':
	     if ((flags & (F_ZFILL|F_WIDTH|F_DOT|F_PREC)) == 0)
	      { flags |= F_ZFILL;
		break;
	      }
	     /* fall through */
	  case '1': case '2': case '3':
	  case '4': case '5': case '6':
	  case '7': case '8': case '9':
	     *dvar = (*dvar * 10) + (*fp - '0');
	     flags |= (flags & F_DOT) ? F_PREC : F_WIDTH;
	     break;
	  case '*':
	     *dvar = va_arg(ap,int);
	     flags |= (flags & F_DOT) ? F_PREC : F_WIDTH;
	     break;
	  case '.':
	     flags |= F_DOT;
	     dvar = &prec;
	     break;
	  case 'h':
	     flags |= F_SHORT;
	     break;
	  case 'l':
	     flags |= F_LONG;
	     break;
	  default:
	     conv = *fp;
	     break;
	}
     }
    if (conv)
     { os = &tmp[0];
       altstr = "";
       altlen = 0;
       switch (conv)
	{ case 'd': case 'i':
	      { int signedp;
		const char *digs;
		long int v;
		unsigned long int uv;
		signedp = 1;
		digs = "0123456789";
		if (0)
		 {
	  case 'u':
		   signedp = 0;
		   digs = "0123456789";
		   altstr = "";
		   altlen = 0;
		 }
		if (0)
		 {
	  case 'o':
		   signedp = 0;
		   digs = "01234567";
		   altstr = "0";
		   altlen = 1;
		 }
		if (0)
		 {
	  case 'x':
		   signedp = 0;
		   digs = "0123456789abcdef";
		   altstr = "0x";
		   altlen = 2;
		 }
		if (0)
		 {
	  case 'X':
		   signedp = 0;
		   digs = "0123456789ABCDEF";
		   altstr = "0X";
		   altlen = 2;
		 }
		if (signedp)
		 { v = (flags & F_LONG) ? va_arg(ap,long int) : va_arg(ap,int);
		   i = (v < 0);
		   uv = i ? -(unsigned long int)v : v;
		 }
		else
		 { uv = (flags & F_LONG) ? va_arg(ap,unsigned long int) : va_arg(ap,unsigned int);
		   i = 0;
		 }
		if ((uv == 0) || !(flags & F_ALT))
		 { altstr = "";
		   altlen = 0;
		 }
		if (0)
		 {
	  case 'p':
		   signedp = 0;
		   digs = "0123456789abcdef";
		   altstr = "0x";
		   altlen = 2;
		   uv = (unsigned long int) va_arg(ap,void *);
		   i = 0;
		 }
		if (i)
		 { noc = cvt_num(&tmp[0],uv,digs);
		   altstr = "-";
		   altlen = 1;
		 }
		else
		 { if (signedp)
		    { if (flags & F_PLUS) altstr = "+";
		      else if (flags & F_SPACE) altstr = " ";
		      else altstr = 0;
		      altlen = altstr ? 1 : 0;
		    }
		   noc = cvt_num(&tmp[0],uv,digs);
		 }
		flags |= F_NUM;
	      }
	     break;
	  case 'c':
	     tmp[0] = va_arg(ap,int);
	     noc = 1;
	     break;
	  case 's':
	     os = va_arg(ap,char *);
	     if (os == 0) os = "(nil pointer)";
	     noc = strlen(os);
	     if ((flags & F_PREC) && (noc > prec)) noc = prec;
	     break;
	  case 'n':
	     *va_arg(ap,int *) = charcount;
	     noc = 0;
	     flags &= ~F_WIDTH;
	     break;
	  case 'f': case 'e': case 'g':
	     os = "(unimplemented)";
	     noc = 15;
	     break;
	  case '%':
	     os = "%";
	     noc = 1;
	     break;
	}
     }
    if (! (flags & F_NUM)) flags &= ~(F_ZFILL|F_PREC);
    nsb = 0;
    nsa = 0;
    nz = 0;
    if ((flags & F_PREC) && (noc < prec)) nz = prec - noc;
    if ((flags & F_WIDTH) && (noc+nz+altlen < width))
     { nsb = width - (noc+nz+altlen);
       if (flags & F_LEFT)
	{ nsa = nsb;
	  nsb = 0;
	}
       if (flags & F_ZFILL)
	{ nz += nsb;
	  nsb = 0;
	}
     }
    charcount += nsb + altlen + nz + noc + nsa;
#define FOO(var,c) do { if (var > 100) { if (fn) { (*fn)(171); (*fn)(c); (*fn)(187); } var = 100; } } while (0)
    FOO(nsb,'b');
    FOO(altlen,'l');
    FOO(nz,'z');
    FOO(noc,'o');
    FOO(nsa,'a');
    if (fn)
     { for (;nsb>0;nsb--) (*fn)(' ');
       for (i=0;i<altlen;i++) (*fn)(altstr[i]);
       for (;nz>0;nz--) (*fn)('0');
       for (i=0;i<noc;i++) (*fn)(os[i]);
       for (;nsa>0;nsa--) (*fn)(' ');
     }
  }
 return(charcount);
#undef F_ALT
#undef F_ZFILL
#undef F_LEFT
#undef F_PLUS
#undef F_SPACE
#undef F_WIDTH
#undef F_DOT
#undef F_PREC
#undef F_SHORT
#undef F_LONG
#undef F_NUM
}