com32/lib/vsnprintf.c

   1 /*
   2  * vsnprintf.c
   3  *
   4  * vsnprintf(), from which the rest of the printf()
   5  * family is built
   6  */
   7
   8 #include <stdarg.h>
   9 #include <stddef.h>
  10 #include <inttypes.h>
  11 #include <string.h>
  12 #include <limits.h>
  13 #include <stdio.h>
  14
  15 enum flags {
  16   FL_ZERO   = 0x01,             /* Zero modifier */
  17   FL_MINUS  = 0x02,             /* Minus modifier */
  18   FL_PLUS   = 0x04,             /* Plus modifier */
  19   FL_TICK   = 0x08,             /* ' modifier */
  20   FL_SPACE  = 0x10,             /* Space modifier */
  21   FL_HASH   = 0x20,             /* # modifier */
  22   FL_SIGNED = 0x40,             /* Number is signed */
  23   FL_UPPER  = 0x80              /* Upper case digits */
  24 };
  25
  26 /* These may have to be adjusted on certain implementations */
  27 enum ranks {
  28   rank_char     = -2,
  29   rank_short    = -1,
  30   rank_int      = 0,
  31   rank_long     = 1,
  32   rank_longlong = 2
  33 };
  34
  35 #define MIN_RANK        rank_char
  36 #define MAX_RANK        rank_longlong
  37
  38 #define INTMAX_RANK     rank_longlong
  39 #define SIZE_T_RANK     rank_long
  40 #define PTRDIFF_T_RANK  rank_long
  41
  42 #define EMIT(x) ({ if (o<n){*q++ = (x);} o++; })
  43
  44 static size_t
  45 format_int(char *q, size_t n, uintmax_t val, enum flags flags,
  46            int base, int width, int prec)
  47 {
  48   char *qq;
  49   size_t o = 0, oo;
  50   static const char lcdigits[] = "0123456789abcdef";
  51   static const char ucdigits[] = "0123456789ABCDEF";
  52   const char *digits;
  53   uintmax_t tmpval;
  54   int minus = 0;
  55   int ndigits = 0, nchars;
  56   int tickskip, b4tick;
  57
  58   /* Select type of digits */
  59   digits = (flags & FL_UPPER) ? ucdigits : lcdigits;
  60
  61   /* If signed, separate out the minus */
  62   if ( flags & FL_SIGNED && (intmax_t)val < 0 ) {
  63     minus = 1;
  64     val = (uintmax_t)(-(intmax_t)val);
  65   }
  66
  67   /* Count the number of digits needed.  This returns zero for 0. */
  68   tmpval = val;
  69   while ( tmpval ) {
  70     tmpval /= base;
  71     ndigits++;
  72   }
  73
  74   /* Adjust ndigits for size of output */
  75
  76   if ( flags & FL_HASH && base == 8 ) {
  77     if ( prec < ndigits+1 )
  78       prec = ndigits+1;
  79   }
  80
  81   if ( ndigits < prec ) {
  82     ndigits = prec;             /* Mandatory number padding */
  83   } else if ( val == 0 ) {
  84     ndigits = 1;                /* Zero still requires space */
  85   }
  86
  87   /* For ', figure out what the skip should be */
  88   if ( flags & FL_TICK ) {
  89     tickskip = (base == 16) ? 4 : 3;
  90   } else {
  91     tickskip = ndigits;         /* No tick marks */
  92   }
  93
  94   /* Tick marks aren't digits, but generated by the number converter */
  95   ndigits += (ndigits-1)/tickskip;
  96
  97   /* Now compute the number of nondigits */
  98   nchars = ndigits;
  99
 100   if ( minus || (flags & (FL_PLUS|FL_SPACE)) )
 101     nchars++;                   /* Need space for sign */
 102   if ( (flags & FL_HASH) && base == 16 ) {
 103     nchars += 2;                /* Add 0x for hex */
 104   }
 105
 106   /* Emit early space padding */
 107   if ( !(flags & (FL_MINUS|FL_ZERO)) && width > nchars ) {
 108     while ( width > nchars ) {
 109       EMIT(' ');
 110       width--;
 111     }
 112   }
 113
 114   /* Emit nondigits */
 115   if ( minus )
 116     EMIT('-');
 117   else if ( flags & FL_PLUS )
 118     EMIT('+');
 119   else if ( flags & FL_SPACE )
 120     EMIT(' ');
 121
 122   if ( (flags & FL_HASH) && base == 16 ) {
 123     EMIT('0');
 124     EMIT((flags & FL_UPPER) ? 'X' : 'x');
 125   }
 126
 127   /* Emit zero padding */
 128   if ( (flags & (FL_MINUS|FL_ZERO)) == FL_ZERO && width > ndigits ) {
 129     while ( width > nchars ) {
 130       EMIT('0');
 131       width--;
 132     }
 133   }
 134
 135   /* Generate the number.  This is done from right to left. */
 136   q += ndigits;                 /* Advance the pointer to end of number */
 137   o += ndigits;
 138   qq = q; oo = o;               /* Temporary values */
 139
 140   b4tick = tickskip;
 141   while ( ndigits > 0 ) {
 142     if ( !b4tick-- ) {
 143       qq--; oo--; ndigits--;
 144       if ( oo < n ) *qq = '_';
 145       b4tick = tickskip-1;
 146     }
 147     qq--; oo--; ndigits--;
 148     if ( oo < n ) *qq = digits[val%base];
 149     val /= base;
 150   }
 151
 152   /* Emit late space padding */
 153   while ( (flags & FL_MINUS) && width > nchars ) {
 154     EMIT(' ');
 155     width--;
 156   }
 157
 158   return o;
 159 }
 160
 161
 162 int vsnprintf(char *buffer, size_t n, const char *format, va_list ap)
 163 {
 164   const char *p = format;
 165   char ch;
 166   char *q = buffer;
 167   size_t o = 0;                 /* Number of characters output */
 168   uintmax_t val = 0;
 169   int rank = rank_int;          /* Default rank */
 170   int width = 0;
 171   int prec  = -1;
 172   int base;
 173   size_t sz;
 174   enum flags flags = 0;
 175   enum {
 176     st_normal,                  /* Ground state */
 177     st_flags,                   /* Special flags */
 178     st_width,                   /* Field width */
 179     st_prec,                    /* Field precision */
 180     st_modifiers                /* Length or conversion modifiers */
 181   } state = st_normal;
 182   const char *sarg;             /* %s string argument */
 183   char carg;                    /* %c char argument */
 184   int slen;                     /* String length */
 185
 186   while ( (ch = *p++) ) {
 187     switch ( state ) {
 188     case st_normal:
 189       if ( ch == '%' ) {
 190         state = st_flags;
 191         flags = 0; rank = rank_int; width = 0; prec = -1;
 192       } else {
 193         EMIT(ch);
 194       }
 195       break;
 196
 197     case st_flags:
 198       switch ( ch ) {
 199       case '-':
 200         flags |= FL_MINUS;
 201         break;
 202       case '+':
 203         flags |= FL_PLUS;
 204         break;
 205       case '\'':
 206         flags |= FL_TICK;
 207         break;
 208       case ' ':
 209         flags |= FL_SPACE;
 210         break;
 211       case '#':
 212         flags |= FL_HASH;
 213         break;
 214       case '0':
 215         flags |= FL_ZERO;
 216         break;
 217       default:
 218         state = st_width;
 219         p--;                    /* Process this character again */
 220         break;
 221       }
 222       break;
 223
 224     case st_width:
 225       if ( ch >= '0' && ch <= '9' ) {
 226         width = width*10+(ch-'0');
 227       } else if ( ch == '*' ) {
 228         width = va_arg(ap, int);
 229         if ( width < 0 ) {
 230           width = -width;
 231           flags |= FL_MINUS;
 232         }
 233       } else if ( ch == '.' ) {
 234         prec = 0;               /* Precision given */
 235         state = st_prec;
 236       } else {
 237         state = st_modifiers;
 238         p--;                    /* Process this character again */
 239       }
 240       break;
 241
 242     case st_prec:
 243       if ( ch >= '0' && ch <= '9' ) {
 244         prec = prec*10+(ch-'0');
 245       } else if ( ch == '*' ) {
 246         prec = va_arg(ap, int);
 247         if ( prec < 0 )
 248           prec = -1;
 249       } else {
 250         state = st_modifiers;
 251         p--;                    /* Process this character again */
 252       }
 253       break;
 254
 255     case st_modifiers:
 256       switch ( ch ) {
 257         /* Length modifiers - nonterminal sequences */
 258       case 'h':
 259         rank--;                 /* Shorter rank */
 260         break;
 261       case 'l':
 262         rank++;                 /* Longer rank */
 263         break;
 264       case 'j':
 265         rank = INTMAX_RANK;
 266         break;
 267       case 'z':
 268         rank = SIZE_T_RANK;
 269         break;
 270       case 't':
 271         rank = PTRDIFF_T_RANK;
 272         break;
 273       case 'L':
 274       case 'q':
 275         rank += 2;
 276         break;
 277       default:
 278         /* Output modifiers - terminal sequences */
 279         state = st_normal;      /* Next state will be normal */
 280         if ( rank < MIN_RANK )  /* Canonicalize rank */
 281           rank = MIN_RANK;
 282         else if ( rank > MAX_RANK )
 283           rank = MAX_RANK;
 284
 285         switch ( ch ) {
 286         case 'P':               /* Upper case pointer */
 287           flags |= FL_UPPER;
 288           /* fall through */
 289         case 'p':               /* Pointer */
 290           base = 16;
 291           prec = (CHAR_BIT*sizeof(void *)+3)/4;
 292           flags |= FL_HASH;
 293           val = (uintmax_t)(uintptr_t)va_arg(ap, void *);
 294           goto is_integer;
 295
 296         case 'd':               /* Signed decimal output */
 297         case 'i':
 298           base = 10;
 299           flags |= FL_SIGNED;
 300           switch (rank) {
 301           case rank_char:
 302             /* Yes, all these casts are needed... */
 303             val = (uintmax_t)(intmax_t)(signed char)va_arg(ap, signed int);
 304             break;
 305           case rank_short:
 306             val = (uintmax_t)(intmax_t)(signed short)va_arg(ap, signed int);
 307             break;
 308           case rank_int:
 309             val = (uintmax_t)(intmax_t)va_arg(ap, signed int);
 310             break;
 311           case rank_long:
 312             val = (uintmax_t)(intmax_t)va_arg(ap, signed long);
 313             break;
 314           case rank_longlong:
 315             val = (uintmax_t)(intmax_t)va_arg(ap, signed long long);
 316             break;
 317           }
 318           goto is_integer;
 319         case 'o':               /* Octal */
 320           base = 8;
 321           goto is_unsigned;
 322         case 'u':               /* Unsigned decimal */
 323           base = 10;
 324           goto is_unsigned;
 325         case 'X':               /* Upper case hexadecimal */
 326           flags |= FL_UPPER;
 327           /* fall through */
 328         case 'x':               /* Hexadecimal */
 329           base = 16;
 330           goto is_unsigned;
 331
 332         is_unsigned:
 333           switch (rank) {
 334           case rank_char:
 335             val = (uintmax_t)(unsigned char)va_arg(ap, unsigned int);
 336             break;
 337           case rank_short:
 338             val = (uintmax_t)(unsigned short)va_arg(ap, unsigned int);
 339             break;
 340           case rank_int:
 341             val = (uintmax_t)va_arg(ap, unsigned int);
 342             break;
 343           case rank_long:
 344             val = (uintmax_t)va_arg(ap, unsigned long);
 345             break;
 346           case rank_longlong:
 347             val = (uintmax_t)va_arg(ap, unsigned long long);
 348             break;
 349           }
 350           /* fall through */
 351
 352         is_integer:
 353           sz = format_int(q, (o<n) ? n-o : 0, val, flags, base, width, prec);
 354           q += sz; o += sz;
 355           break;
 356
 357         case 'c':               /* Character */
 358           carg = (char)va_arg(ap, int);
 359           sarg = &carg;
 360           slen = 1;
 361           goto is_string;
 362         case 's':               /* String */
 363           sarg = va_arg(ap, const char *);
 364           sarg = sarg ? sarg : "(null)";
 365           slen = strlen(sarg);
 366           goto is_string;
 367
 368         is_string:
 369           {
 370             char sch;
 371             int i;
 372
 373             if ( prec != -1 && slen > prec )
 374               slen = prec;
 375
 376             if ( width > slen && !(flags & FL_MINUS) ) {
 377               char pad = (flags & FL_ZERO) ? '0' : ' ';
 378               while ( width > slen ) {
 379                 EMIT(pad);
 380                 width--;
 381               }
 382             }
 383             for ( i = slen ; i ; i-- ) {
 384               sch = *sarg++;
 385               EMIT(sch);
 386             }
 387             if ( width > slen && (flags & FL_MINUS) ) {
 388               while ( width > slen ) {
 389                 EMIT(' ');
 390                 width--;
 391               }
 392             }
 393           }
 394           break;
 395
 396         case 'n':               /* Output the number of characters written */
 397           {
 398             switch (rank) {
 399             case rank_char:
 400               *va_arg(ap, signed char *) = o;
 401               break;
 402             case rank_short:
 403               *va_arg(ap, signed short *) = o;
 404               break;
 405             case rank_int:
 406               *va_arg(ap, signed int *) = o;
 407               break;
 408             case rank_long:
 409               *va_arg(ap, signed long *) = o;
 410               break;
 411             case rank_longlong:
 412               *va_arg(ap, signed long long *) = o;
 413               break;
 414             }
 415           }
 416           break;
 417
 418         default:                /* Anything else, including % */
 419           EMIT(ch);
 420           break;
 421         }
 422       }
 423     }
 424   }
 425
 426   /* Null-terminate the string */
 427   if ( o<n )
 428     *q = '\0';                  /* No overflow */
 429   else if ( n>0 )
 430     buffer[n-1] = '\0';         /* Overflow - terminate at end of buffer */
 431
 432   return o;
 433 }