vsprintf.c

GNU Mach 微内核源代码, 基于美国卡内基美隆大学的 Mach 研究项目

/*
 *  linux/lib/vsprintf.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/* vsprintf.c -- Lars Wirzenius & Linus Torvalds. */
/*
 * Wirzenius wrote this portably, Torvalds fucked it up :-)
 */

#include <sys/types.h>

#define MACH_INCLUDE
#include <stdarg.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/ctype.h>

unsigned long 
simple_strtoul (const char *cp, char **endp, unsigned int base)
{
  unsigned long result = 0, value;

  if (!base)
    {
      base = 10;
      if (*cp == '0')
	{
	  base = 8;
	  cp++;
	  if ((*cp == 'x') && isxdigit (cp[1]))
	    {
	      cp++;
	      base = 16;
	    }
	}
    }
  while (isxdigit (*cp)
	 && (value = isdigit (*cp) ? *cp - '0'
	     : (islower (*cp) ? toupper (*cp) : *cp) - 'A' + 10) < base)
    {
      result = result * base + value;
      cp++;
    }
  if (endp)
    *endp = (char *) cp;
  return result;
}

/* we use this so that we can do without the ctype library */
#define is_digit(c)	((c) >= '0' && (c) <= '9')

static int
skip_atoi (const char **s)
{
  int i = 0;

  while (is_digit (**s))
    i = i * 10 + *((*s)++) - '0';
  return i;
}

#define ZEROPAD	1		/* pad with zero */
#define SIGN	2		/* unsigned/signed long */
#define PLUS	4		/* show plus */
#define SPACE	8		/* space if plus */
#define LEFT	16		/* left justified */
#define SPECIAL	32		/* 0x */
#define LARGE	64		/* use 'ABCDEF' instead of 'abcdef' */

#define do_div(n,base) ({ \
int __res; \
__res = ((unsigned long) n) % (unsigned) base; \
n = ((unsigned long) n) / (unsigned) base; \
__res; })

static char *
number (char *str, long num, int base, int size, int precision, int type)
{
  char c, sign, tmp[66];
  const char *digits = "0123456789abcdefghijklmnopqrstuvwxyz";
  int i;

  if (type & LARGE)
    digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  if (type & LEFT)
    type &= ~ZEROPAD;
  if (base < 2 || base > 36)
    return 0;
  c = (type & ZEROPAD) ? '0' : ' ';
  sign = 0;
  if (type & SIGN)
    {
      if (num < 0)
	{
	  sign = '-';
	  num = -num;
	  size--;
	}
      else if (type & PLUS)
	{
	  sign = '+';
	  size--;
	}
      else if (type & SPACE)
	{
	  sign = ' ';
	  size--;
	}
    }
  if (type & SPECIAL)
    {
      if (base == 16)
	size -= 2;
      else if (base == 8)
	size--;
    }
  i = 0;
  if (num == 0)
    tmp[i++] = '0';
  else
    while (num != 0)
      tmp[i++] = digits[do_div (num, base)];
  if (i > precision)
    precision = i;
  size -= precision;
  if (!(type & (ZEROPAD + LEFT)))
    while (size-- > 0)
      *str++ = ' ';
  if (sign)
    *str++ = sign;
  if (type & SPECIAL)
    {
      if (base == 8)
	{
	  *str++ = '0';
	}
      else if (base == 16)
	{
	  *str++ = '0';
	  *str++ = digits[33];
	}
    }
  if (!(type & LEFT))
    while (size-- > 0)
      *str++ = c;
  while (i < precision--)
    *str++ = '0';
  while (i-- > 0)
    *str++ = tmp[i];
  while (size-- > 0)
    *str++ = ' ';
  return str;
}

int
linux_vsprintf (char *buf, const char *fmt, va_list args)
{
  int len;
  unsigned long num;
  int i, base;
  char *str;
  const char *s;

  int flags;			/* flags to number() */

  int field_width;		/* width of output field */
  int precision;		/* min. # of digits for integers; max
				 * number of chars for from string
				 */
  int qualifier;		/* 'h', 'l', or 'L' for integer fields */

  for (str = buf; *fmt; ++fmt)
    {
      if (*fmt != '%')
	{
	  *str++ = *fmt;
	  continue;
	}

      /* process flags */
      flags = 0;
    repeat:
      ++fmt;			/* this also skips first '%' */
      switch (*fmt)
	{
	case '-':
	  flags |= LEFT;
	  goto repeat;
	case '+':
	  flags |= PLUS;
	  goto repeat;
	case ' ':
	  flags |= SPACE;
	  goto repeat;
	case '#':
	  flags |= SPECIAL;
	  goto repeat;
	case '0':
	  flags |= ZEROPAD;
	  goto repeat;
	}

      /* get field width */
      field_width = -1;
      if (is_digit (*fmt))
	field_width = skip_atoi (&fmt);
      else if (*fmt == '*')
	{
	  ++fmt;
	  /* it's the next argument */
	  field_width = va_arg (args, int);
	  if (field_width < 0)
	    {
	      field_width = -field_width;
	      flags |= LEFT;
	    }
	}

      /* get the precision */
      precision = -1;
      if (*fmt == '.')
	{
	  ++fmt;
	  if (is_digit (*fmt))
	    precision = skip_atoi (&fmt);
	  else if (*fmt == '*')
	    {
	      ++fmt;
	      /* it's the next argument */
	      precision = va_arg (args, int);
	    }
	  if (precision < 0)
	    precision = 0;
	}

      /* get the conversion qualifier */
      qualifier = -1;
      if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L')
	{
	  qualifier = *fmt;
	  ++fmt;
	}

      /* default base */
      base = 10;

      switch (*fmt)
	{
	case 'c':
	  if (!(flags & LEFT))
	    while (--field_width > 0)
	      *str++ = ' ';
	  *str++ = (unsigned char) va_arg (args, int);
	  while (--field_width > 0)
	    *str++ = ' ';
	  continue;

	case 's':
	  s = va_arg (args, char *);
	  if (!s)
	    s = "<NULL>";

	  len = strnlen (s, precision);

	  if (!(flags & LEFT))
	    while (len < field_width--)
	      *str++ = ' ';
	  for (i = 0; i < len; ++i)
	    *str++ = *s++;
	  while (len < field_width--)
	    *str++ = ' ';
	  continue;

	case 'p':
	  if (field_width == -1)
	    {
	      field_width = 2 * sizeof (void *);
	      flags |= ZEROPAD;
	    }
	  str = number (str,
			(unsigned long) va_arg (args, void *), 16,
			field_width, precision, flags);
	  continue;


	case 'n':
	  if (qualifier == 'l')
	    {
	      long *ip = va_arg (args, long *);
	      *ip = (str - buf);
	    }
	  else
	    {
	      int *ip = va_arg (args, int *);
	      *ip = (str - buf);
	    }
	  continue;

	  /* integer number formats - set up the flags and "break" */
	case 'o':
	  base = 8;
	  break;

	case 'X':
	  flags |= LARGE;
	case 'x':
	  base = 16;
	  break;

	case 'd':
	case 'i':
	  flags |= SIGN;
	case 'u':
	  break;

	default:
	  if (*fmt != '%')
	    *str++ = '%';
	  if (*fmt)
	    *str++ = *fmt;
	  else
	    --fmt;
	  continue;
	}
      if (qualifier == 'l')
	num = va_arg (args, unsigned long);
      else if (qualifier == 'h')
	if (flags & SIGN)
	  num = va_arg (args, short);
	else
	  num = va_arg (args, unsigned short);
      else if (flags & SIGN)
	num = va_arg (args, int);
      else
	num = va_arg (args, unsigned int);
      str = number (str, num, base, field_width, precision, flags);
    }
  *str = '\0';
  return str - buf;
}

int
linux_sprintf (char *buf, const char *fmt,...)
{
  va_list args;
  int i;

  va_start (args, fmt);
  i = linux_vsprintf (buf, fmt, args);
  va_end (args);
  return i;
}