vsprintf.c

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/*-
 * Copyright (c) 2002-2018 The UbixOS Project.
 * All rights reserved.
 *
 * This was developed by Christopher W. Olsen for the UbixOS Project.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
 *
 * 1) Redistributions of source code must retain the above copyright notice, this list of
 *    conditions, the following disclaimer and the list of authors.
 * 2) Redistributions in binary form must reproduce the above copyright notice, this list of
 *    conditions, the following disclaimer and the list of authors in the documentation and/or
 *    other materials provided with the distribution.
 * 3) Neither the name of the UbixOS Project nor the names of its contributors may be used to
 *    endorse or promote products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
/* vsprintf.c -- Lars Wirzenius & Linus Torvalds. */
/*
 * Wirzenius wrote this portably, Torvalds fucked it up :-)
 */
 
#include <stdarg.h>
#include <string.h>
 
/* 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 SMALL   64              /* use 'abcdef' instead of 'ABCDEF' */
 
#define do_div(n,base) ({ \
int __res; \
__asm__("divl %4":"=a" (n),"=d" (__res):"0" (n),"1" (0),"r" (base)); \
__res; })
 
static char * number(char * str, int num, int base, int size, int precision, int type) {
  char c, sign, tmp[36];
  const char *digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  int i;
 
  if (type & SMALL)
    digits = "0123456789abcdefghijklmnopqrstuvwxyz";
  if (type & LEFT)
    type &= ~ZEROPAD;
  if (base < 2 || base > 36)
    return 0;
  c = (type & ZEROPAD) ? '0' : ' ';
  if ((type & SIGN) && num < 0) {
    sign = '-';
    num = -num;
  }
  else
    sign = (type & PLUS) ? '+' : ((type & SPACE) ? ' ' : 0);
  if (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 vsprintf(char *buf, const char *fmt, va_list args) {
  int len;
  int i;
  char * str;
  char *s;
  int *ip;
 
  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 == '*') {
      /* 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 == '*') {
        /* 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;
    }
 
    switch (*fmt) {
      case 'c':
        if (!(flags & LEFT))
          while (--field_width > 0)
            *str++ = ' ';
        *str++ = (unsigned char) va_arg(args, int);
        while (--field_width > 0)
          *str++ = ' ';
      break;
 
      case 's':
        s = va_arg(args, char *);
        len = strlen(s);
        if (precision < 0)
          precision = len;
        else if (len > precision)
          len = precision;
 
        if (!(flags & LEFT))
          while (len < field_width--)
            *str++ = ' ';
        for (i = 0; i < len; ++i)
          *str++ = *s++;
        while (len < field_width--)
          *str++ = ' ';
      break;
 
      case 'o':
        str = number(str, va_arg(args, unsigned long), 8, field_width, precision, flags);
      break;
 
      case 'p':
        if (field_width == -1) {
          field_width = 8;
          flags |= ZEROPAD;
        }
        str = number(str, (unsigned long) va_arg(args, void *), 16, field_width, precision, flags);
      break;
 
      case 'x':
        flags |= SMALL;
      case 'X':
        str = number(str, va_arg(args, unsigned long), 16, field_width, precision, flags);
      break;
 
      case 'd':
      case 'i':
        flags |= SIGN;
      case 'u':
        str = number(str, va_arg(args, unsigned long), 10, field_width, precision, flags);
      break;
 
      case 'n':
        ip = va_arg(args, int *);
        *ip = (str - buf);
      break;
 
      default:
        if (*fmt != '%')
          *str++ = '%';
        if (*fmt)
          *str++ = *fmt;
        else
          --fmt;
      break;
    }
  }
  *str = '\0';
  return str - buf;
}
 
/***
 END
 ***/