kernel/vsprintf.c

   1 /*
   2  *  linux/kernel/vsprintf.c
   3  *
   4  *  (C) 1991  Linus Torvalds
   5  */
   6
   7 /* vsprintf.c -- Lars Wirzenius & Linus Torvalds. */
   8 /*
   9  * Wirzenius wrote this portably, Torvalds fucked it up :-)
  10  */
  11 #include <stdarg.h>
  12 #include <string.h>
  13
  14 /* we use this so that we can do without the ctype library */
  15 #define is_digit(c)     ((c) >= '0' && (c) <= '9')
  16
  17 static int skip_atoi(const char **s)
  18 {
  19         int i=0;
  20
  21         while (is_digit(**s))
  22                 i = i*10 + *((*s)++) - '0';
  23         return i;
  24 }
  25
  26 #define ZEROPAD 1               /* pad with zero */
  27 #define SIGN    2               /* unsigned/signed long */
  28 #define PLUS    4               /* show plus */
  29 #define SPACE   8               /* space if plus */
  30 #define LEFT    16              /* left justified */
  31 #define SPECIAL 32              /* 0x */
  32 #define SMALL   64              /* use 'abcdef' instead of 'ABCDEF' */
  33
  34 #define do_div(n,base) ({                                            \
  35                         int __res;                                   \
  36                         __asm__("divl %4":"=a" (n),"=d" (__res):"0" (n),"1" (0),"r" (base)); \
  37                         __res; })
  38 /*
  39   static int do_div (int num, int base)
  40 {
  41   int res;
  42   res = num % base;
  43   num = num / base;
  44   return res;
  45 }
  46 */
  47 static char * number(char * str, int num, int base, int size, int precision
  48                      ,int type)
  49 {
  50         char c,sign,tmp[36];
  51         const char *digits="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  52         int i;
  53
  54         if (type&SMALL) digits="0123456789abcdefghijklmnopqrstuvwxyz";
  55         if (type&LEFT) type &= ~ZEROPAD;
  56         if (base<2 || base>36)
  57                 return 0;
  58         c = (type & ZEROPAD) ? '0' : ' ' ;
  59         if (type&SIGN && num<0) {
  60                 sign='-';
  61                 num = -num;
  62         } else
  63                 sign=(type&PLUS) ? '+' : ((type&SPACE) ? ' ' : 0);
  64         if (sign) size--;
  65         if (type&SPECIAL) {
  66                 if (base==16) size -= 2;
  67                 else if (base==8) size--;
  68         }
  69         i=0;
  70         if (num==0)
  71                 tmp[i++]='0';
  72         else while (num!=0)
  73                      tmp[i++]=digits[do_div(num,base)];
  74         if (i>precision) precision=i;
  75         size -= precision;
  76         if (!(type&(ZEROPAD+LEFT)))
  77                 while(size-->0)
  78                         *str++ = ' ';
  79         if (sign)
  80                 *str++ = sign;
  81         if (type&SPECIAL) {
  82                 if (base==8)
  83                         *str++ = '0';
  84                 else if (base==16) {
  85                         *str++ = '0';
  86                         *str++ = digits[33];
  87                 }
  88         }
  89         if (!(type&LEFT))
  90                 while(size-->0)
  91                         *str++ = c;
  92         while(i<precision--)
  93                 *str++ = '0';
  94         while(i-->0)
  95                 *str++ = tmp[i];
  96         while(size-->0)
  97                 *str++ = ' ';
  98         return str;
  99 }
 100
 101 int vsprintf(char *buf, const char *fmt, va_list args)
 102 {
 103         int len;
 104         int i;
 105         char * str;
 106         char *s;
 107         int *ip;
 108
 109         int flags;              /* flags to number() */
 110
 111         int field_width;        /* width of output field */
 112         int precision;          /* min. # of digits for integers; max
 113                                    number of chars for from string */
 114         int qualifier;          /* 'h', 'l', or 'L' for integer fields */
 115
 116         for (str=buf ; *fmt ; ++fmt) {
 117                 if (*fmt != '%') {
 118                         *str++ = *fmt;
 119                         continue;
 120                 }
 121
 122                 /* process flags */
 123                 flags = 0;
 124         repeat:
 125                 ++fmt;          /* this also skips first '%' */
 126                 switch (*fmt) {
 127                 case '-': flags |= LEFT; goto repeat;
 128                 case '+': flags |= PLUS; goto repeat;
 129                 case ' ': flags |= SPACE; goto repeat;
 130                 case '#': flags |= SPECIAL; goto repeat;
 131                 case '0': flags |= ZEROPAD; goto repeat;
 132                 }
 133
 134                 /* get field width */
 135                 field_width = -1;
 136                 if (is_digit(*fmt))
 137                         field_width = skip_atoi(&fmt);
 138                 else if (*fmt == '*') {
 139                         /* it's the next argument */
 140                         field_width = va_arg(args,int);
 141                         if (field_width < 0) {
 142                                 field_width = -field_width;
 143                                 flags |= LEFT;
 144                         }
 145                 }
 146
 147                 /* get the precision */
 148                 precision = -1;
 149                 if (*fmt == '.') {
 150                         ++fmt;
 151                         if (is_digit(*fmt))
 152                                 precision = skip_atoi(&fmt);
 153                         else if (*fmt == '*') {
 154                                 /* it's the next argument */
 155                                 ++ fmt;
 156                                 precision = va_arg(args,int);
 157                         }
 158                         if (precision < 0)
 159                                 precision = 0;
 160                 }
 161
 162                 /* get the conversion qualifier */
 163                 qualifier = -1;
 164                 if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L') {
 165                         qualifier = *fmt;
 166                         ++fmt;
 167     }
 168
 169                 switch (*fmt) {
 170                 case 'c':
 171                         if (!(flags & LEFT))
 172                                 while (--field_width > 0)
 173                                         *str++ = ' ';
 174                         *str++ = (unsigned char) va_arg(args,int);
 175                         while (--field_width > 0)
 176                                 *str++ = ' ';
 177                         break;
 178
 179                 case 's':
 180                         s = va_arg(args,char *);
 181                         len = strlen(s);
 182                         if (precision < 0)
 183                                 precision = len;
 184                         else if (len > precision)
 185                                 len = precision;
 186
 187                         if (!(flags & LEFT))
 188                                 while (len < field_width--)
 189                                         *str++ = ' ';
 190                         for (i = 0; i < len; ++i)
 191                                 *str++ = *s++;
 192                         while (len < field_width--)
 193                                 *str++ = ' ';
 194                         break;
 195
 196                 case 'o':
 197                         str = number(str, va_arg(args,unsigned long), 8,
 198                                      field_width, precision, flags);
 199                         break;
 200
 201                 case 'p':
 202                         if (field_width == -1) {
 203                                 field_width = 8;
 204                                 flags |= ZEROPAD;
 205                         }
 206                         str = number(str,
 207                                      (unsigned long) va_arg(args,void *), 16,
 208                                      field_width, precision, flags);
 209                         break;
 210
 211                 case 'x':
 212                         flags |= SMALL;
 213                 case 'X':
 214                         str = number(str, va_arg(args,unsigned long), 16,
 215                                      field_width, precision, flags);
 216                         break;
 217
 218                 case 'd':
 219                 case 'i':
 220                         flags |= SIGN;
 221                 case 'u':
 222                         str = number(str, va_arg(args,unsigned long), 10,
 223                                      field_width, precision, flags);
 224                         break;
 225
 226                 case 'n':
 227                         ip = va_arg(args,int *);
 228                         *ip = (str - buf);
 229                         break;
 230
 231                 default:
 232                         if (*fmt != '%')
 233                                 *str++ = '%';
 234                         if (*fmt)
 235                                 *str++ = *fmt;
 236                         else
 237                                 --fmt;
 238                         break;
 239                 }
 240         }
 241         *str = '\0';
 242         return str-buf;
 243 }