printf.c

PIC_INLINE int
xvfprintf(xFILE *stream, const char *fmt, va_list ap)
{
  int flags, width, precision, length;
  enum {
    ALT = 1,
    ZERO = 2,
    LEFT = 4,
    SIGN = 8,
    SPACE = 16
  };
  enum {
    LEN_H = 1,
    LEN_L = 2
  };
  const char *p;
  union {
    char *sval;
    int ival;
    short hval;
    long lval;
    double dval;
  } u;
  char buf[256], bufp;

  for (p = fmt; *p; p++) {
    if (*p != '%') {
      xputc(*p, stream);
      continue;
    } else {
      p++;
      goto FLAGS;
    }

  FLAGS:
    flags = 0;
    while (1) {
      switch (*p) {
      case '#':
        flags |= ALT;
        break;
      case '0':
        flags |= ZERO;
        break;
      case '+':
        flags |= SIGN;
        break;
      case '-':
        flags |= LEFT;
        break;
      case ' ':
        flags |= SPACE;
        break;
      default:
        goto WIDTH;
      }
      p++;
    }

  WIDTH:
    width = 0;
    while (1) {
      switch (*p) {
      case '0': case '1': case '2': case '3': case '4':
      case '5': case '6': case '7': case '8': case '9':
        width = width * 10 + *p - '0';
        break;
      case '*':
        width = va_arg(ap, int);
      default:
        goto PRECISION;
      }
      p++;
    }

  PRECISION:
    precision = -1;
    if (*p == '.') {
      precision = 0;
      p++;
      while (1) {
        switch (*p) {
        case '0': case '1': case '2': case '3': case '4':
        case '5': case '6': case '7': case '8': case '9':
          precision = precision * 10 + *p - '0';
          break;
        case '*':
          precision = va_arg(ap, int);
        default:
          goto LENGTH;
        }
        p++;
      }
    }

  LENGTH:
    length = 0;
    switch (*p) {
    case 'h':
      p++;
      length = LEN_H;
      goto SPECIFIER;
    case 'l':
      p++;
      length = LEN_L;
      goto SPECIFIER;
    }

  SPECIFIER:                    /* TODO */
    switch (*p) {
    case 'd': case 'i':
    case 'u': case 'o': case 'x': case 'X':
    case 'f': case 'F': case 'e': case 'E':
    case 'g': case 'G': case 'a': case 'A':
    case 'c':
    case 's':
    case 'p':
    case '%':
    default:
      return -1;
    }
  }
}