sample/printf.c

   1 /*
   2  * Oh, it's a waste of space, but oh-so-yummy for debugging.  It's just
   3  * initialization code anyway, so it doesn't take up space when we're
   4  * actually running.  This version of printf() does not include 64-bit
   5  * support.  "Live with it."
   6  *
   7  * Most of this code was shamelessly snarfed from the Linux kernel, then
   8  * modified.
   9  *
  10  * FIX THIS: Replace printf() implementation with BSD/MIT-licensed one
  11  * from klibc
  12  */
  13
  14 #include <stdarg.h>
  15
  16 int puts(const char *);
  17
  18 static inline int
  19 isdigit(int ch)
  20 {
  21   return (ch >= '0') && (ch <= '9');
  22 }
  23
  24 unsigned int skip_atou(const char **s);
  25 unsigned int atou(const char *s);
  26
  27 static int strnlen(const char *s, int maxlen)
  28 {
  29   const char *es = s;
  30   while ( *es && maxlen ) {
  31     es++; maxlen--;
  32   }
  33
  34   return (es-s);
  35 }
  36
  37 #define ZEROPAD 1               /* pad with zero */
  38 #define SIGN    2               /* unsigned/signed long */
  39 #define PLUS    4               /* show plus */
  40 #define SPACE   8               /* space if plus */
  41 #define LEFT    16              /* left justified */
  42 #define SPECIAL 32              /* 0x */
  43 #define LARGE   64              /* use 'ABCDEF' instead of 'abcdef' */
  44
  45 #define do_div(n,base) ({ \
  46 int __res; \
  47 __res = ((unsigned long) n) % (unsigned) base; \
  48 n = ((unsigned long) n) / (unsigned) base; \
  49 __res; })
  50
  51 static char * number(char * str, long num, int base, int size, int precision
  52         ,int type)
  53 {
  54   char c,sign,tmp[66];
  55   const char *digits="0123456789abcdefghijklmnopqrstuvwxyz";
  56   int i;
  57
  58   if (type & LARGE)
  59     digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  60   if (type & LEFT)
  61     type &= ~ZEROPAD;
  62   if (base < 2 || base > 36)
  63     return 0;
  64   c = (type & ZEROPAD) ? '0' : ' ';
  65   sign = 0;
  66   if (type & SIGN) {
  67     if (num < 0) {
  68       sign = '-';
  69       num = -num;
  70       size--;
  71     } else if (type & PLUS) {
  72       sign = '+';
  73       size--;
  74     } else if (type & SPACE) {
  75       sign = ' ';
  76       size--;
  77     }
  78   }
  79   if (type & SPECIAL) {
  80     if (base == 16)
  81       size -= 2;
  82     else if (base == 8)
  83       size--;
  84   }
  85   i = 0;
  86   if (num == 0)
  87     tmp[i++]='0';
  88   else while (num != 0)
  89     tmp[i++] = digits[do_div(num,base)];
  90   if (i > precision)
  91     precision = i;
  92   size -= precision;
  93   if (!(type&(ZEROPAD+LEFT)))
  94     while(size-->0)
  95       *str++ = ' ';
  96   if (sign)
  97     *str++ = sign;
  98   if (type & SPECIAL) {
  99     if (base==8)
 100       *str++ = '0';
 101     else if (base==16) {
 102       *str++ = '0';
 103       *str++ = digits[33];
 104     }
 105   }
 106   if (!(type & LEFT))
 107     while (size-- > 0)
 108       *str++ = c;
 109   while (i < precision--)
 110     *str++ = '0';
 111   while (i-- > 0)
 112     *str++ = tmp[i];
 113   while (size-- > 0)
 114     *str++ = ' ';
 115   return str;
 116 }
 117
 118 /* Forward decl. needed for IP address printing stuff... */
 119 int sprintf(char * buf, const char *fmt, ...);
 120
 121 int vsprintf(char *buf, const char *fmt, va_list args)
 122 {
 123   int len;
 124   unsigned long num;
 125   int i, base;
 126   char * str;
 127   const char *s;
 128
 129   int flags;            /* flags to number() */
 130
 131   int field_width;      /* width of output field */
 132   int precision;                /* min. # of digits for integers; max
 133                                    number of chars for from string */
 134   int qualifier;                /* 'h', 'l', or 'L' for integer fields */
 135
 136   for (str=buf ; *fmt ; ++fmt) {
 137     if (*fmt != '%') {
 138       *str++ = *fmt;
 139       continue;
 140     }
 141
 142     /* process flags */
 143     flags = 0;
 144   repeat:
 145     ++fmt;              /* this also skips first '%' */
 146     switch (*fmt) {
 147     case '-': flags |= LEFT; goto repeat;
 148     case '+': flags |= PLUS; goto repeat;
 149     case ' ': flags |= SPACE; goto repeat;
 150     case '#': flags |= SPECIAL; goto repeat;
 151     case '0': flags |= ZEROPAD; goto repeat;
 152     }
 153
 154     /* get field width */
 155     field_width = -1;
 156     if (isdigit(*fmt))
 157       field_width = skip_atou(&fmt);
 158     else if (*fmt == '*') {
 159       ++fmt;
 160       /* it's the next argument */
 161       field_width = va_arg(args, int);
 162       if (field_width < 0) {
 163         field_width = -field_width;
 164         flags |= LEFT;
 165       }
 166     }
 167
 168     /* get the precision */
 169     precision = -1;
 170     if (*fmt == '.') {
 171       ++fmt;
 172       if (isdigit(*fmt))
 173         precision = skip_atou(&fmt);
 174       else if (*fmt == '*') {
 175         ++fmt;
 176         /* it's the next argument */
 177         precision = va_arg(args, int);
 178       }
 179       if (precision < 0)
 180         precision = 0;
 181     }
 182
 183     /* get the conversion qualifier */
 184     qualifier = -1;
 185     if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L') {
 186       qualifier = *fmt;
 187       ++fmt;
 188     }
 189
 190     /* default base */
 191     base = 10;
 192
 193     switch (*fmt) {
 194     case 'c':
 195       if (!(flags & LEFT))
 196         while (--field_width > 0)
 197           *str++ = ' ';
 198       *str++ = (unsigned char) va_arg(args, int);
 199       while (--field_width > 0)
 200         *str++ = ' ';
 201       continue;
 202
 203     case 's':
 204       s = va_arg(args, char *);
 205       len = strnlen(s, precision);
 206
 207       if (!(flags & LEFT))
 208         while (len < field_width--)
 209           *str++ = ' ';
 210       for (i = 0; i < len; ++i)
 211         *str++ = *s++;
 212       while (len < field_width--)
 213         *str++ = ' ';
 214       continue;
 215
 216     case 'p':
 217       if (field_width == -1) {
 218         field_width = 2*sizeof(void *);
 219         flags |= ZEROPAD;
 220       }
 221       str = number(str,
 222                    (unsigned long) va_arg(args, void *), 16,
 223                    field_width, precision, flags);
 224       continue;
 225
 226
 227     case 'n':
 228       if (qualifier == 'l') {
 229         long * ip = va_arg(args, long *);
 230         *ip = (str - buf);
 231       } else {
 232         int * ip = va_arg(args, int *);
 233         *ip = (str - buf);
 234       }
 235       continue;
 236
 237     case '%':
 238       *str++ = '%';
 239       continue;
 240
 241       /* integer number formats - set up the flags and "break" */
 242     case 'o':
 243       base = 8;
 244       break;
 245
 246     case 'X':
 247       flags |= LARGE;
 248     case 'x':
 249       base = 16;
 250       break;
 251
 252     case 'd':
 253     case 'i':
 254       flags |= SIGN;
 255     case 'u':
 256       break;
 257
 258     default:
 259       *str++ = '%';
 260       if (*fmt)
 261         *str++ = *fmt;
 262       else
 263         --fmt;
 264       continue;
 265     }
 266     if (qualifier == 'l')
 267       num = va_arg(args, unsigned long);
 268     else if (qualifier == 'h') {
 269       num = (unsigned short) va_arg(args, int);
 270       if (flags & SIGN)
 271         num = (short) num;
 272     } else if (flags & SIGN)
 273       num = va_arg(args, int);
 274     else
 275       num = va_arg(args, unsigned int);
 276     str = number(str, num, base, field_width, precision, flags);
 277   }
 278   *str = '\0';
 279   return str-buf;
 280 }
 281
 282 int sprintf(char * buf, const char *fmt, ...)
 283 {
 284   va_list args;
 285   int i;
 286
 287   va_start(args, fmt);
 288   i=vsprintf(buf,fmt,args);
 289   va_end(args);
 290   return i;
 291 }
 292
 293 int printf(const char *fmt, ...)
 294 {
 295   char printf_buf[1024];
 296   va_list args;
 297   int printed;
 298
 299   va_start(args, fmt);
 300   printed = vsprintf(printf_buf, fmt, args);
 301   va_end(args);
 302
 303   puts(printf_buf);
 304
 305   return printed;
 306 }