pack.c

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/**********************************************************************

  pack.c -

  $Author: nobu $
  $Date: 2005/10/13 14:30:49 $
  created at: Thu Feb 10 15:17:05 JST 1994

  Copyright (C) 1993-2003 Yukihiro Matsumoto

**********************************************************************/

#include "ruby.h"
#include <sys/types.h>
#include <ctype.h>

#define SIZE16 2
#define SIZE32 4

#if SIZEOF_SHORT != 2 || SIZEOF_LONG != 4
# define NATINT_PACK
#endif

#ifdef NATINT_PACK
# define OFF16B(p) ((char*)(p) + (natint?0:(sizeof(short) - SIZE16)))
# define OFF32B(p) ((char*)(p) + (natint?0:(sizeof(long) - SIZE32)))
# define NATINT_LEN(type,len) (natint?sizeof(type):(len))
# ifdef WORDS_BIGENDIAN
#   define OFF16(p) OFF16B(p)
#   define OFF32(p) OFF32B(p)
# endif
# define NATINT_HTOVS(x) (natint?htovs(x):htov16(x))
# define NATINT_HTOVL(x) (natint?htovl(x):htov32(x))
# define NATINT_HTONS(x) (natint?htons(x):hton16(x))
# define NATINT_HTONL(x) (natint?htonl(x):hton32(x))
#else
# define NATINT_LEN(type,len) sizeof(type)
# define NATINT_HTOVS(x) htovs(x)
# define NATINT_HTOVL(x) htovl(x)
# define NATINT_HTONS(x) htons(x)
# define NATINT_HTONL(x) htonl(x)
#endif

#ifndef OFF16
# define OFF16(p) (char*)(p)
# define OFF32(p) (char*)(p)
#endif
#ifndef OFF16B
# define OFF16B(p) (char*)(p)
# define OFF32B(p) (char*)(p)
#endif

#define define_swapx(x, xtype)          \
static xtype                            \
TOKEN_PASTE(swap,x)(z)                  \
    xtype z;                            \
{                                       \
    xtype r;                            \
    xtype *zp;                          \
    unsigned char *s, *t;               \
    int i;                              \
                                        \
    zp = malloc(sizeof(xtype));         \
    *zp = z;                            \
    s = (unsigned char*)zp;             \
    t = malloc(sizeof(xtype));          \
    for (i=0; i<sizeof(xtype); i++) {   \
        t[sizeof(xtype)-i-1] = s[i];    \
    }                                   \
    r = *(xtype *)t;                    \
    free(t);                            \
    free(zp);                           \
    return r;                           \
}

#ifndef swap16
#define swap16(x)       ((((x)&0xFF)<<8) | (((x)>>8)&0xFF))
#endif
#if SIZEOF_SHORT == 2
#define swaps(x)        swap16(x)
#else
#if SIZEOF_SHORT == 4
#define swaps(x)        ((((x)&0xFF)<<24)       \
                        |(((x)>>24)&0xFF)       \
                        |(((x)&0x0000FF00)<<8)  \
                        |(((x)&0x00FF0000)>>8)  )
#else
define_swapx(s,short)
#endif
#endif

#ifndef swap32
#define swap32(x)       ((((x)&0xFF)<<24)       \
                        |(((x)>>24)&0xFF)       \
                        |(((x)&0x0000FF00)<<8)  \
                        |(((x)&0x00FF0000)>>8)  )
#endif
#if SIZEOF_LONG == 4
#define swapl(x)        swap32(x)
#else
#if SIZEOF_LONG == 8
#define swapl(x)        ((((x)&0x00000000000000FF)<<56) \
                        |(((x)&0xFF00000000000000)>>56) \
                        |(((x)&0x000000000000FF00)<<40) \
                        |(((x)&0x00FF000000000000)>>40) \
                        |(((x)&0x0000000000FF0000)<<24) \
                        |(((x)&0x0000FF0000000000)>>24) \
                        |(((x)&0x00000000FF000000)<<8)  \
                        |(((x)&0x000000FF00000000)>>8))
#else
define_swapx(l,long)
#endif
#endif

#if SIZEOF_FLOAT == 4
#if SIZEOF_LONG == 4    /* SIZEOF_FLOAT == 4 == SIZEOF_LONG */
#define swapf(x)        swapl(x)
#define FLOAT_SWAPPER   unsigned long
#else
#if SIZEOF_SHORT == 4   /* SIZEOF_FLOAT == 4 == SIZEOF_SHORT */
#define swapf(x)        swaps(x)
#define FLOAT_SWAPPER   unsigned short
#else   /* SIZEOF_FLOAT == 4 but undivide by known size of int */
define_swapx(f,float)
#endif  /* #if SIZEOF_SHORT == 4 */
#endif  /* #if SIZEOF_LONG == 4 */
#else   /* SIZEOF_FLOAT != 4 */
define_swapx(f,float)
#endif  /* #if SIZEOF_FLOAT == 4 */

#if SIZEOF_DOUBLE == 8
#if SIZEOF_LONG == 8    /* SIZEOF_DOUBLE == 8 == SIZEOF_LONG */
#define swapd(x)        swapl(x)
#define DOUBLE_SWAPPER  unsigned long
#else
#if SIZEOF_LONG == 4    /* SIZEOF_DOUBLE == 8 && 4 == SIZEOF_LONG */
static double
swapd(d)
    const double d;
{
    double dtmp = d;
    unsigned long utmp[2];
    unsigned long utmp0;

    utmp[0] = 0; utmp[1] = 0;
    memcpy(utmp,&dtmp,sizeof(double));
    utmp0 = utmp[0];
    utmp[0] = swapl(utmp[1]);
    utmp[1] = swapl(utmp0);
    memcpy(&dtmp,utmp,sizeof(double));
    return dtmp;
}
#else
#if SIZEOF_SHORT == 4   /* SIZEOF_DOUBLE == 8 && 4 == SIZEOF_SHORT */
static double
swapd(d)
    const double d;
{
    double dtmp = d;
    unsigned short utmp[2];
    unsigned short utmp0;

    utmp[0] = 0; utmp[1] = 0;
    memcpy(utmp,&dtmp,sizeof(double));
    utmp0 = utmp[0];
    utmp[0] = swaps(utmp[1]);
    utmp[1] = swaps(utmp0);
    memcpy(&dtmp,utmp,sizeof(double));
    return dtmp;
}
#else   /* SIZEOF_DOUBLE == 8 but undivied by known size of int */
define_swapx(d, double)
#endif  /* #if SIZEOF_SHORT == 4 */
#endif  /* #if SIZEOF_LONG == 4 */
#endif  /* #if SIZEOF_LONG == 8 */
#else   /* SIZEOF_DOUBLE != 8 */
define_swapx(d, double)
#endif  /* #if SIZEOF_DOUBLE == 8 */

#undef define_swapx

#ifdef DYNAMIC_ENDIAN
#ifdef ntohs
#undef ntohs
#undef ntohl
#undef htons
#undef htonl
#endif
static int
endian()
{
    static int init = 0;
    static int endian_value;
    char *p;

    if (init) return endian_value;
    init = 1;
    p = (char*)&init;
    return endian_value = p[0]?0:1;
}

#define ntohs(x) (endian()?(x):swaps(x))
#define ntohl(x) (endian()?(x):swapl(x))
#define ntohf(x) (endian()?(x):swapf(x))
#define ntohd(x) (endian()?(x):swapd(x))
#define htons(x) (endian()?(x):swaps(x))
#define htonl(x) (endian()?(x):swapl(x))
#define htonf(x) (endian()?(x):swapf(x))
#define htond(x) (endian()?(x):swapd(x))
#define htovs(x) (endian()?swaps(x):(x))
#define htovl(x) (endian()?swapl(x):(x))
#define htovf(x) (endian()?swapf(x):(x))
#define htovd(x) (endian()?swapd(x):(x))
#define vtohs(x) (endian()?swaps(x):(x))
#define vtohl(x) (endian()?swapl(x):(x))
#define vtohf(x) (endian()?swapf(x):(x))
#define vtohd(x) (endian()?swapd(x):(x))
# ifdef NATINT_PACK
#define htov16(x) (endian()?swap16(x):(x))
#define htov32(x) (endian()?swap32(x):(x))
#define hton16(x) (endian()?(x):swap16(x))
#define hton32(x) (endian()?(x):swap32(x))
# endif
#else
#ifdef WORDS_BIGENDIAN
#ifndef ntohs
#define ntohs(x) (x)
#define ntohl(x) (x)
#define htons(x) (x)
#define htonl(x) (x)
#endif
#define ntohf(x) (x)
#define ntohd(x) (x)
#define htonf(x) (x)
#define htond(x) (x)
#define htovs(x) swaps(x)
#define htovl(x) swapl(x)
#define htovf(x) swapf(x)
#define htovd(x) swapd(x)
#define vtohs(x) swaps(x)
#define vtohl(x) swapl(x)
#define vtohf(x) swapf(x)
#define vtohd(x) swapd(x)
# ifdef NATINT_PACK
#define htov16(x) swap16(x)
#define htov32(x) swap32(x)
#define hton16(x) (x)
#define hton32(x) (x)
# endif
#else /* LITTLE ENDIAN */
#ifdef ntohs
#undef ntohs
#undef ntohl
#undef htons
#undef htonl
#endif
#define ntohs(x) swaps(x)
#define ntohl(x) swapl(x)
#define htons(x) swaps(x)
#define htonl(x) swapl(x)
#define ntohf(x) swapf(x)
#define ntohd(x) swapd(x)
#define htonf(x) swapf(x)
#define htond(x) swapd(x)
#define htovs(x) (x)
#define htovl(x) (x)
#define htovf(x) (x)
#define htovd(x) (x)
#define vtohs(x) (x)
#define vtohl(x) (x)
#define vtohf(x) (x)
#define vtohd(x) (x)
# ifdef NATINT_PACK
#define htov16(x) (x)
#define htov32(x) (x)
#define hton16(x) swap16(x)
#define hton32(x) swap32(x)
# endif
#endif
#endif

#ifdef FLOAT_SWAPPER
#define FLOAT_CONVWITH(y)       FLOAT_SWAPPER y;
#define HTONF(x,y)      (memcpy(&y,&x,sizeof(float)),   \
                         y = htonf((FLOAT_SWAPPER)y),   \
                         memcpy(&x,&y,sizeof(float)),   \
                         x)
#define HTOVF(x,y)      (memcpy(&y,&x,sizeof(float)),   \
                         y = htovf((FLOAT_SWAPPER)y),   \
                         memcpy(&x,&y,sizeof(float)),   \
                         x)
#define NTOHF(x,y)      (memcpy(&y,&x,sizeof(float)),   \
                         y = ntohf((FLOAT_SWAPPER)y),   \
                         memcpy(&x,&y,sizeof(float)),   \
                         x)
#define VTOHF(x,y)      (memcpy(&y,&x,sizeof(float)),   \
                         y = vtohf((FLOAT_SWAPPER)y),   \
                         memcpy(&x,&y,sizeof(float)),   \
                         x)
#else
#define FLOAT_CONVWITH(y)
#define HTONF(x,y)      htonf(x)
#define HTOVF(x,y)      htovf(x)
#define NTOHF(x,y)      ntohf(x)
#define VTOHF(x,y)      vtohf(x)
#endif

#ifdef DOUBLE_SWAPPER
#define DOUBLE_CONVWITH(y)      DOUBLE_SWAPPER y;
#define HTOND(x,y)      (memcpy(&y,&x,sizeof(double)),  \
                         y = htond((DOUBLE_SWAPPER)y),  \
                         memcpy(&x,&y,sizeof(double)),  \
                         x)
#define HTOVD(x,y)      (memcpy(&y,&x,sizeof(double)),  \
                         y = htovd((DOUBLE_SWAPPER)y),  \
                         memcpy(&x,&y,sizeof(double)),  \
                         x)
#define NTOHD(x,y)      (memcpy(&y,&x,sizeof(double)),  \
                         y = ntohd((DOUBLE_SWAPPER)y),  \
                         memcpy(&x,&y,sizeof(double)),  \
                         x)
#define VTOHD(x,y)      (memcpy(&y,&x,sizeof(double)),  \
                         y = vtohd((DOUBLE_SWAPPER)y),  \
                         memcpy(&x,&y,sizeof(double)),  \
                         x)
#else
#define DOUBLE_CONVWITH(y)
#define HTOND(x,y)      htond(x)
#define HTOVD(x,y)      htovd(x)
#define NTOHD(x,y)      ntohd(x)
#define VTOHD(x,y)      vtohd(x)
#endif

unsigned long rb_big2ulong_pack (VALUE x);

static unsigned long
num2i32(x)
    VALUE x;
{
    x = rb_to_int(x); /* is nil OK? (should not) */

    if (FIXNUM_P(x)) return FIX2LONG(x);
    if (TYPE(x) == T_BIGNUM) {
        return rb_big2ulong_pack(x);
    }
    rb_raise(rb_eTypeError, "can't convert %s to `integer'", rb_obj_classname(x));
    return 0;                   /* not reached */
}

#if SIZEOF_LONG == SIZE32 || SIZEOF_INT == SIZE32
# define EXTEND32(x) 
#else
/* invariant in modulo 1<<31 */
# define EXTEND32(x) do {if (!natint) {(x) = (I32)(((1<<31)-1-(x))^~(~0<<31));}} while(0)
#endif
#if SIZEOF_SHORT == SIZE16
# define EXTEND16(x) 
#else
# define EXTEND16(x) do { if (!natint) {(x) = (short)(((1<<15)-1-(x))^~(~0<<15));}} while(0)
#endif

#ifdef HAVE_LONG_LONG
# define QUAD_SIZE sizeof(LONG_LONG)
#else
# define QUAD_SIZE 8
#endif
static char *toofew = "too few arguments";

static void encodes (VALUE,char*,long,int);
static void qpencode (VALUE,VALUE,long);

static int uv_to_utf8 (char*,unsigned long);
static unsigned long utf8_to_uv (char*,long*);

/*
 *  call-seq:
 *     arr.pack ( aTemplateString ) -> aBinaryString
 *  
 *  Packs the contents of <i>arr</i> into a binary sequence according to
 *  the directives in <i>aTemplateString</i> (see the table below)
 *  Directives ``A,'' ``a,'' and ``Z'' may be followed by a count,
 *  which gives the width of the resulting field. The remaining
 *  directives also may take a count, indicating the number of array
 *  elements to convert. If the count is an asterisk
 *  (``<code>*</code>''), all remaining array elements will be
 *  converted. Any of the directives ``<code>sSiIlL</code>'' may be
 *  followed by an underscore (``<code>_</code>'') to use the underlying
 *  platform's native size for the specified type; otherwise, they use a
 *  platform-independent size. Spaces are ignored in the template
 *  string. See also <code>String#unpack</code>.
 *     
 *     a = [ "a", "b", "c" ]
 *     n = [ 65, 66, 67 ]
 *     a.pack("A3A3A3")   #=> "a  b  c  "
 *     a.pack("a3a3a3")   #=> "a\000\000b\000\000c\000\000"
 *     n.pack("ccc")      #=> "ABC"
 *     
 *  Directives for +pack+.
 *
 *   Directive    Meaning
 *   ---------------------------------------------------------------
 *       @     |  Moves to absolute position
 *       A     |  ASCII string (space padded, count is width)
 *       a     |  ASCII string (null padded, count is width)
 *       B     |  Bit string (descending bit order)
 *       b     |  Bit string (ascending bit order)
 *       C     |  Unsigned char
 *       c     |  Char
 *       D, d  |  Double-precision float, native format
 *       E     |  Double-precision float, little-endian byte order
 *       e     |  Single-precision float, little-endian byte order
 *       F, f  |  Single-precision float, native format
 *       G     |  Double-precision float, network (big-endian) byte order
 *       g     |  Single-precision float, network (big-endian) byte order
 *       H     |  Hex string (high nibble first)
 *       h     |  Hex string (low nibble first)
 *       I     |  Unsigned integer
 *       i     |  Integer
 *       L     |  Unsigned long
 *       l     |  Long
 *       M     |  Quoted printable, MIME encoding (see RFC2045)
 *       m     |  Base64 encoded string
 *       N     |  Long, network (big-endian) byte order
 *       n     |  Short, network (big-endian) byte-order
 *       P     |  Pointer to a structure (fixed-length string)
 *       p     |  Pointer to a null-terminated string
 *       Q, q  |  64-bit number
 *       S     |  Unsigned short
 *       s     |  Short
 *       U     |  UTF-8
 *       u     |  UU-encoded string
 *       V     |  Long, little-endian byte order
 *       v     |  Short, little-endian byte order
 *       w     |  BER-compressed integer\fnm
 *       X     |  Back up a byte
 *       x     |  Null byte
 *       Z     |  Same as ``a'', except that null is added with *
 */

static VALUE
pack_pack(ary, fmt)
    VALUE ary, fmt;
{
    static char *nul10 = "\0\0\0\0\0\0\0\0\0\0";
    static char *spc10 = "          ";
    char *p, *pend;
    VALUE res, from, associates = 0;
    char type;
    long items, len, idx, plen;
    char *ptr;
#ifdef NATINT_PACK
    int natint;         /* native integer */
#endif

    StringValue(fmt);
    p = RSTRING(fmt)->ptr;
    pend = p + RSTRING(fmt)->len;
    res = rb_str_buf_new(0);

    items = RARRAY(ary)->len;
    idx = 0;

#define THISFROM RARRAY(ary)->ptr[idx]
#define NEXTFROM (items-- > 0 ? RARRAY(ary)->ptr[idx++] : (rb_raise(rb_eArgError, toofew),0))

    while (p < pend) {
        if (RSTRING(fmt)->ptr + RSTRING(fmt)->len != pend) {
            rb_raise(rb_eRuntimeError, "format string modified");
        }
        type = *p++;            /* get data type */
#ifdef NATINT_PACK
        natint = 0;
#endif

        if (ISSPACE(type)) continue;
        if (type == '#') {
            while ((p < pend) && (*p != '\n')) {
                p++;
            }
            continue;
        }
        if (*p == '_' || *p == '!') {
            const char *natstr = "sSiIlL";

            if (strchr(natstr, type)) {
#ifdef NATINT_PACK
                natint = 1;
#endif
                p++;
            }
            else {
                rb_raise(rb_eArgError, "'%c' allowed only after types %s", *p, natstr);
            }
        }
        if (*p == '*') {        /* set data length */
            len = strchr("@Xxu", type) ? 0 : items;
            p++;
        }
        else if (ISDIGIT(*p)) {
            len = strtoul(p, (char**)&p, 10);
        }
        else {
            len = 1;
        }

        switch (type) {
          case 'A': case 'a': case 'Z':
          case 'B': case 'b':
          case 'H': case 'h':
            from = NEXTFROM;
            if (NIL_P(from)) {
                ptr = "";
                plen = 0;
            }
            else {
                StringValue(from);
                ptr = RSTRING(from)->ptr;
                plen = RSTRING(from)->len;
                OBJ_INFECT(res, from);
            }

            if (p[-1] == '*')
                len = plen;

            switch (type) {
              case 'a':         /* arbitrary binary string (null padded)  */
              case 'A':         /* ASCII string (space padded) */
              case 'Z':         /* null terminated ASCII string  */
                if (plen >= len) {
                    rb_str_buf_cat(res, ptr, len);
                    if (p[-1] == '*' && type == 'Z')
                        rb_str_buf_cat(res, nul10, 1);
                }
                else {
                    rb_str_buf_cat(res, ptr, plen);
                    len -= plen;
                    while (len >= 10) {
                        rb_str_buf_cat(res, (type == 'A')?spc10:nul10, 10);
                        len -= 10;
                    }
                    rb_str_buf_cat(res, (type == 'A')?spc10:nul10, len);
                }
                break;

              case 'b':         /* bit string (ascending) */
                {
                    int byte = 0;
                    long i, j = 0;

                    if (len > plen) {
                        j = (len - plen + 1)/2;
                        len = plen;
                    }
                    for (i=0; i++ < len; ptr++) {
                        if (*ptr & 1)
                            byte |= 128;
                        if (i & 7)
                            byte >>= 1;
                        else {
                            char c = byte & 0xff;
                            rb_str_buf_cat(res, &c, 1);
                            byte = 0;
                        }
                    }
                    if (len & 7) {
                        char c;
                        byte >>= 7 - (len & 7);
                        c = byte & 0xff;
                        rb_str_buf_cat(res, &c, 1);
                    }
                    len = j;
                    goto grow;
                }
                break;

              case 'B':         /* bit string (descending) */
                {
                    int byte = 0;
                    long i, j = 0;

                    if (len > plen) {
                        j = (len - plen + 1)/2;
                        len = plen;
                    }
                    for (i=0; i++ < len; ptr++) {
                        byte |= *ptr & 1;
                        if (i & 7)
                            byte <<= 1;
                        else {
                            char c = byte & 0xff;
                            rb_str_buf_cat(res, &c, 1);
                            byte = 0;
                        }
                    }
                    if (len & 7) {
                        char c;
                        byte <<= 7 - (len & 7);
                        c = byte & 0xff;
                        rb_str_buf_cat(res, &c, 1);
                    }
                    len = j;
                    goto grow;
                }
                break;

              case 'h':         /* hex string (low nibble first) */
                {
                    int byte = 0;
                    long i, j = 0;

                    if (len > plen) {
                        j = (len - plen + 1)/2;
                        len = plen;
                    }
                    for (i=0; i++ < len; ptr++) {
                        if (ISALPHA(*ptr))
                            byte |= (((*ptr & 15) + 9) & 15) << 4;
                        else
                            byte |= (*ptr & 15) << 4;
                        if (i & 1)
                            byte >>= 4;
                        else {
                            char c = byte & 0xff;
                            rb_str_buf_cat(res, &c, 1);
                            byte = 0;
                        }
                    }
                    if (len & 1) {
                        char c = byte & 0xff;
                        rb_str_buf_cat(res, &c, 1);
                    }
                    len = j;
                    goto grow;
                }
                break;

              case 'H':         /* hex string (high nibble first) */
                {
                    int byte = 0;
                    long i, j = 0;

                    if (len > plen) {
                        j = (len - plen + 1)/2;
                        len = plen;
                    }
                    for (i=0; i++ < len; ptr++) {
                        if (ISALPHA(*ptr))
                            byte |= ((*ptr & 15) + 9) & 15;
                        else
                            byte |= *ptr & 15;
                        if (i & 1)
                            byte <<= 4;
                        else {
                            char c = byte & 0xff;
                            rb_str_buf_cat(res, &c, 1);
                            byte = 0;
                        }
                    }
                    if (len & 1) {
                        char c = byte & 0xff;
                        rb_str_buf_cat(res, &c, 1);
                    }
                    len = j;
                    goto grow;
                }
                break;
            }
            break;

          case 'c':             /* signed char */
          case 'C':             /* unsigned char */
            while (len-- > 0) {
                char c;

                from = NEXTFROM;
                c = num2i32(from);
                rb_str_buf_cat(res, &c, sizeof(char));
            }
            break;

          case 's':             /* signed short */
          case 'S':             /* unsigned short */
            while (len-- > 0) {
                short s;

                from = NEXTFROM;
                s = num2i32(from);
                rb_str_buf_cat(res, OFF16(&s), NATINT_LEN(short,2));
            }
            break;

          case 'i':             /* signed int */
          case 'I':             /* unsigned int */
            while (len-- > 0) {
                long i;

                from = NEXTFROM;
                i = num2i32(from);
                rb_str_buf_cat(res, OFF32(&i), NATINT_LEN(int,4));
            }
            break;

          case 'l':             /* signed long */
          case 'L':             /* unsigned long */
            while (len-- > 0) {
                long l;

                from = NEXTFROM;
                l = num2i32(from);
                rb_str_buf_cat(res, OFF32(&l), NATINT_LEN(long,4));
            }
            break;

          case 'q':             /* signed quad (64bit) int */
          case 'Q':             /* unsigned quad (64bit) int */
            while (len-- > 0) {
                char tmp[QUAD_SIZE];

                from = NEXTFROM;
                rb_quad_pack(tmp, from);
                rb_str_buf_cat(res, (char*)&tmp, QUAD_SIZE);
            }
            break;

          case 'n':             /* unsigned short (network byte-order)  */
            while (len-- > 0) {
                unsigned short s;

                from = NEXTFROM;
                s = num2i32(from);
                s = NATINT_HTONS(s);
                rb_str_buf_cat(res, OFF16(&s), NATINT_LEN(short,2));
            }
            break;

          case 'N':             /* unsigned long (network byte-order) */
            while (len-- > 0) {
                unsigned long l;

                from = NEXTFROM;
                l = num2i32(from);
                l = NATINT_HTONL(l);
                rb_str_buf_cat(res, OFF32(&l), NATINT_LEN(long,4));
            }
            break;

          case 'v':             /* unsigned short (VAX byte-order) */
            while (len-- > 0) {
                unsigned short s;

                from = NEXTFROM;
                s = num2i32(from);
                s = NATINT_HTOVS(s);
                rb_str_buf_cat(res, OFF16(&s), NATINT_LEN(short,2));
            }
            break;

          case 'V':             /* unsigned long (VAX byte-order) */
            while (len-- > 0) {
                unsigned long l;

                from = NEXTFROM;
                l = num2i32(from);
                l = NATINT_HTOVL(l);
                rb_str_buf_cat(res, OFF32(&l), NATINT_LEN(long,4));
            }
            break;

          case 'f':             /* single precision float in native format */
          case 'F':             /* ditto */
            while (len-- > 0) {
                float f;

                from = NEXTFROM;
                f = RFLOAT(rb_Float(from))->value;
                rb_str_buf_cat(res, (char*)&f, sizeof(float));
            }
            break;

          case 'e':             /* single precision float in VAX byte-order */
            while (len-- > 0) {
                float f;
                FLOAT_CONVWITH(ftmp);

                from = NEXTFROM;
                f = RFLOAT(rb_Float(from))->value;
                f = HTOVF(f,ftmp);
                rb_str_buf_cat(res, (char*)&f, sizeof(float));
            }
            break;

          case 'E':             /* double precision float in VAX byte-order */
            while (len-- > 0) {
                double d;
                DOUBLE_CONVWITH(dtmp);

                from = NEXTFROM;
                d = RFLOAT(rb_Float(from))->value;
                d = HTOVD(d,dtmp);
                rb_str_buf_cat(res, (char*)&d, sizeof(double));
            }
            break;

          case 'd':             /* double precision float in native format */
          case 'D':             /* ditto */
            while (len-- > 0) {
                double d;

                from = NEXTFROM;
                d = RFLOAT(rb_Float(from))->value;
                rb_str_buf_cat(res, (char*)&d, sizeof(double));
            }
            break;

          case 'g':             /* single precision float in network byte-order */
            while (len-- > 0) {
                float f;
                FLOAT_CONVWITH(ftmp);

                from = NEXTFROM;
                f = RFLOAT(rb_Float(from))->value;
                f = HTONF(f,ftmp);
                rb_str_buf_cat(res, (char*)&f, sizeof(float));
            }
            break;

          case 'G':             /* double precision float in network byte-order */
            while (len-- > 0) {
                double d;
                DOUBLE_CONVWITH(dtmp);

                from = NEXTFROM;
                d = RFLOAT(rb_Float(from))->value;
                d = HTOND(d,dtmp);
                rb_str_buf_cat(res, (char*)&d, sizeof(double));
            }
            break;

          case 'x':             /* null byte */
          grow:
            while (len >= 10) {
                rb_str_buf_cat(res, nul10, 10);
                len -= 10;
            }
            rb_str_buf_cat(res, nul10, len);
            break;

          case 'X':             /* back up byte */
          shrink:
            plen = RSTRING(res)->len;
            if (plen < len)
                rb_raise(rb_eArgError, "X outside of string");
            RSTRING(res)->len = plen - len;
            RSTRING(res)->ptr[plen - len] = '\0';
            break;

          case '@':             /* null fill to absolute position */
            len -= RSTRING(res)->len;
            if (len > 0) goto grow;
            len = -len;
            if (len > 0) goto shrink;
            break;

          case '%':
            rb_raise(rb_eArgError, "%% is not supported");
            break;

          case 'U':             /* Unicode character */
            while (len-- > 0) {
                long l;
                char buf[8];
                int le;

                from = NEXTFROM;
                from = rb_to_int(from);
                l = NUM2INT(from);
                if (l < 0) {
                    rb_raise(rb_eRangeError, "pack(U): value out of range");
                }
                le = uv_to_utf8(buf, l);
                rb_str_buf_cat(res, (char*)buf, le);
            }
            break;

          case 'u':             /* uuencoded string */
          case 'm':             /* base64 encoded string */
            from = NEXTFROM;
            StringValue(from);
            ptr = RSTRING(from)->ptr;
            plen = RSTRING(from)->len;

            if (len <= 2)
                len = 45;
            else
                len = len / 3 * 3;
            while (plen > 0) {
                long todo;

                if (plen > len)
                    todo = len;
                else
                    todo = plen;
                encodes(res, ptr, todo, type);
                plen -= todo;
                ptr += todo;
            }
            break;

          case 'M':             /* quoted-printable encoded string */
            from = rb_obj_as_string(NEXTFROM);
            if (len <= 1)
                len = 72;
            qpencode(res, from, len);
            break;

          case 'P':             /* pointer to packed byte string */
            from = THISFROM;
            if (!NIL_P(from)) {
                StringValue(from);
                if (RSTRING(from)->len < len) {
                    rb_raise(rb_eArgError, "too short buffer for P(%ld for %ld)",
                             RSTRING(from)->len, len);
                }
            }
            len = 1;
            /* FALL THROUGH */
          case 'p':             /* pointer to string */
            while (len-- > 0) {
                char *t;
                from = NEXTFROM;
                if (NIL_P(from)) {
                    t = 0;
                }
                else {
                    t = StringValuePtr(from);
                }
                if (!associates) {
                    associates = rb_ary_new();
                }
                rb_ary_push(associates, from);
                rb_str_buf_cat(res, (char*)&t, sizeof(char*));
            }
            break;

          case 'w':             /* BER compressed integer  */
            while (len-- > 0) {
                unsigned long ul;
                VALUE buf = rb_str_new(0, 0);
                char c, *bufs, *bufe;

                from = NEXTFROM;
                if (TYPE(from) == T_BIGNUM) {
                    VALUE big128 = rb_uint2big(128);
                    while (TYPE(from) == T_BIGNUM) {
                        from = rb_big_divmod(from, big128);
                        c = NUM2INT(RARRAY(from)->ptr[1]) | 0x80; /* mod */
                        rb_str_buf_cat(buf, &c, sizeof(char));
                        from = RARRAY(from)->ptr[0]; /* div */
                    }
                }

                {
                    long l = NUM2LONG(from);
                    if (l < 0) {
                        rb_raise(rb_eArgError, "can't compress negative numbers");
                    }
                    ul = l;
                }

                while (ul) {
                    c = ((ul & 0x7f) | 0x80);
                    rb_str_buf_cat(buf, &c, sizeof(char));
                    ul >>=  7;
                }

                if (RSTRING(buf)->len) {
                    bufs = RSTRING(buf)->ptr;
                    bufe = bufs + RSTRING(buf)->len - 1;
                    *bufs &= 0x7f; /* clear continue bit */
                    while (bufs < bufe) { /* reverse */
                        c = *bufs;
                        *bufs++ = *bufe;
                        *bufe-- = c;
                    }
                    rb_str_buf_cat(res, RSTRING(buf)->ptr, RSTRING(buf)->len);
                }
                else {
                    c = 0;
                    rb_str_buf_cat(res, &c, sizeof(char));
                }
            }
            break;

          default:
            break;
        }
    }

    if (associates) {
        rb_str_associate(res, associates);
    }
    return res;
}

static char uu_table[] =
"`!\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_";
static char b64_table[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

static void
encodes(str, s, len, type)
    VALUE str;
    char *s;
    long len;
    int type;
{
    char *buff = ALLOCA_N(char, len * 4 / 3 + 6);
    long i = 0;
    char *trans = type == 'u' ? uu_table : b64_table;
    int padding;

    if (type == 'u') {
        buff[i++] = len + ' ';
        padding = '`';
    }
    else {
        padding = '=';
    }
    while (len >= 3) {
        buff[i++] = trans[077 & (*s >> 2)];
        buff[i++] = trans[077 & (((*s << 4) & 060) | ((s[1] >> 4) & 017))];
        buff[i++] = trans[077 & (((s[1] << 2) & 074) | ((s[2] >> 6) & 03))];
        buff[i++] = trans[077 & s[2]];
        s += 3;
        len -= 3;
    }
    if (len == 2) {
        buff[i++] = trans[077 & (*s >> 2)];
        buff[i++] = trans[077 & (((*s << 4) & 060) | ((s[1] >> 4) & 017))];
        buff[i++] = trans[077 & (((s[1] << 2) & 074) | (('\0' >> 6) & 03))];
        buff[i++] = padding;
    }
    else if (len == 1) {
        buff[i++] = trans[077 & (*s >> 2)];
        buff[i++] = trans[077 & (((*s << 4) & 060) | (('\0' >> 4) & 017))];
        buff[i++] = padding;
        buff[i++] = padding;
    }
    buff[i++] = '\n';
    rb_str_buf_cat(str, buff, i);
}

static char hex_table[] = "0123456789ABCDEF";

static void
qpencode(str, from, len)
    VALUE str, from;
    long len;
{
    char buff[1024];
    long i = 0, n = 0, prev = EOF;
    unsigned char *s = (unsigned char*)RSTRING(from)->ptr;
    unsigned char *send = s + RSTRING(from)->len;

    while (s < send) {
        if ((*s > 126) ||
            (*s < 32 && *s != '\n' && *s != '\t') ||
            (*s == '=')) {
            buff[i++] = '=';
            buff[i++] = hex_table[*s >> 4];
            buff[i++] = hex_table[*s & 0x0f];
            n += 3;
            prev = EOF;
        }
        else if (*s == '\n') {
            if (prev == ' ' || prev == '\t') {
                buff[i++] = '=';
                buff[i++] = *s;
            }
            buff[i++] = *s;
            n = 0;
            prev = *s;
        }
        else {
            buff[i++] = *s;
            n++;
            prev = *s;
        }
        if (n > len) {
            buff[i++] = '=';
            buff[i++] = '\n';
            n = 0;
            prev = '\n';
        }
        if (i > 1024 - 5) {
            rb_str_buf_cat(str, buff, i);
            i = 0;
        }
        s++;
    }
    if (n > 0) {
        buff[i++] = '=';
        buff[i++] = '\n';
    }
    if (i > 0) {
        rb_str_buf_cat(str, buff, i);
    }
}

static inline int
hex2num(c)
    char c;
{
    switch (c) {
    case '0': case '1': case '2': case '3': case '4':
    case '5': case '6': case '7': case '8': case '9':
        return c - '0';
    case 'a': case 'b': case 'c':
    case 'd': case 'e': case 'f':
        return c - 'a' + 10;
    case 'A': case 'B': case 'C':
    case 'D': case 'E': case 'F':
        return c - 'A' + 10;
    default:
        return -1;
    }
}

#define PACK_LENGTH_ADJUST_SIZE(sz) do {        \
    tmp = 0;                                    \
    if (len > (send-s)/sz) {                    \
        if (!star) {                            \
            tmp = len-(send-s)/sz;              \
        }                                       \
        len = (send-s)/sz;                      \
    }                                           \
} while (0)

#ifdef NATINT_PACK
#define PACK_LENGTH_ADJUST(type,sz) do {        \
    int t__len = NATINT_LEN(type,(sz));         \
    PACK_LENGTH_ADJUST_SIZE(t__len);            \
} while (0)
#else
#define PACK_LENGTH_ADJUST(type,sz)             \
    PACK_LENGTH_ADJUST_SIZE(sizeof(type))
#endif

#define PACK_ITEM_ADJUST() while (tmp--) rb_ary_push(ary, Qnil)

static VALUE
infected_str_new(ptr, len, str)
    const char *ptr;
    long len;
    VALUE str;
{
    VALUE s = rb_str_new(ptr, len);

    OBJ_INFECT(s, str);
    return s;
}
    
/*
 *  call-seq:
 *     str.unpack(format)   => anArray
 *  
 *  Decodes <i>str</i> (which may contain binary data) according to the
 *  format string, returning an array of each value extracted. The
 *  format string consists of a sequence of single-character directives,
 *  summarized in the table at the end of this entry.
 *  Each directive may be followed
 *  by a number, indicating the number of times to repeat with this
 *  directive. An asterisk (``<code>*</code>'') will use up all
 *  remaining elements. The directives <code>sSiIlL</code> may each be
 *  followed by an underscore (``<code>_</code>'') to use the underlying
 *  platform's native size for the specified type; otherwise, it uses a
 *  platform-independent consistent size. Spaces are ignored in the
 *  format string. See also <code>Array#pack</code>.
 *     
 *     "abc \0\0abc \0\0".unpack('A6Z6')   #=> ["abc", "abc "]
 *     "abc \0\0".unpack('a3a3')           #=> ["abc", " \000\000"]
 *     "abc \0abc \0".unpack('Z*Z*')       #=> ["abc ", "abc "]
 *     "aa".unpack('b8B8')                 #=> ["10000110", "01100001"]
 *     "aaa".unpack('h2H2c')               #=> ["16", "61", 97]
 *     "\xfe\xff\xfe\xff".unpack('sS')     #=> [-2, 65534]
 *     "now=20is".unpack('M*')             #=> ["now is"]
 *     "whole".unpack('xax2aX2aX1aX2a')    #=> ["h", "e", "l", "l", "o"]
 *
 *  This table summarizes the various formats and the Ruby classes
 *  returned by each.
 *     
 *     Format | Returns | Function
 *     -------+---------+-----------------------------------------
 *       A    | String  | with trailing nulls and spaces removed
 *     -------+---------+-----------------------------------------
 *       a    | String  | string
 *     -------+---------+-----------------------------------------
 *       B    | String  | extract bits from each character (msb first)
 *     -------+---------+-----------------------------------------
 *       b    | String  | extract bits from each character (lsb first)
 *     -------+---------+-----------------------------------------
 *       C    | Fixnum  | extract a character as an unsigned integer
 *     -------+---------+-----------------------------------------
 *       c    | Fixnum  | extract a character as an integer
 *     -------+---------+-----------------------------------------
 *       d,D  | Float   | treat sizeof(double) characters as
 *            |         | a native double
 *     -------+---------+-----------------------------------------
 *       E    | Float   | treat sizeof(double) characters as
 *            |         | a double in little-endian byte order
 *     -------+---------+-----------------------------------------
 *       e    | Float   | treat sizeof(float) characters as
 *            |         | a float in little-endian byte order
 *     -------+---------+-----------------------------------------
 *       f,F  | Float   | treat sizeof(float) characters as
 *            |         | a native float
 *     -------+---------+-----------------------------------------
 *       G    | Float   | treat sizeof(double) characters as
 *            |         | a double in network byte order
 *     -------+---------+-----------------------------------------
 *       g    | Float   | treat sizeof(float) characters as a
 *            |         | float in network byte order
 *     -------+---------+-----------------------------------------
 *       H    | String  | extract hex nibbles from each character
 *            |         | (most significant first)
 *     -------+---------+-----------------------------------------
 *       h    | String  | extract hex nibbles from each character
 *            |         | (least significant first)
 *     -------+---------+-----------------------------------------
 *       I    | Integer | treat sizeof(int) (modified by _)
 *            |         | successive characters as an unsigned
 *            |         | native integer
 *     -------+---------+-----------------------------------------
 *       i    | Integer | treat sizeof(int) (modified by _)
 *            |         | successive characters as a signed
 *            |         | native integer
 *     -------+---------+-----------------------------------------
 *       L    | Integer | treat four (modified by _) successive
 *            |         | characters as an unsigned native
 *            |         | long integer
 *     -------+---------+-----------------------------------------
 *       l    | Integer | treat four (modified by _) successive
 *            |         | characters as a signed native
 *            |         | long integer
 *     -------+---------+-----------------------------------------
 *       M    | String  | quoted-printable
 *     -------+---------+-----------------------------------------
 *       m    | String  | base64-encoded
 *     -------+---------+-----------------------------------------
 *       N    | Integer | treat four characters as an unsigned
 *            |         | long in network byte order
 *     -------+---------+-----------------------------------------
 *       n    | Fixnum  | treat two characters as an unsigned
 *            |         | short in network byte order
 *     -------+---------+-----------------------------------------
 *       P    | String  | treat sizeof(char *) characters as a
 *            |         | pointer, and  return \emph{len} characters
 *            |         | from the referenced location
 *     -------+---------+-----------------------------------------
 *       p    | String  | treat sizeof(char *) characters as a
 *            |         | pointer to a  null-terminated string
 *     -------+---------+-----------------------------------------
 *       Q    | Integer | treat 8 characters as an unsigned 
 *            |         | quad word (64 bits)
 *     -------+---------+-----------------------------------------
 *       q    | Integer | treat 8 characters as a signed 
 *            |         | quad word (64 bits)
 *     -------+---------+-----------------------------------------
 *       S    | Fixnum  | treat two (different if _ used)
 *            |         | successive characters as an unsigned
 *            |         | short in native byte order
 *     -------+---------+-----------------------------------------
 *       s    | Fixnum  | Treat two (different if _ used) 
 *            |         | successive characters as a signed short
 *            |         | in native byte order
 *     -------+---------+-----------------------------------------
 *       U    | Integer | UTF-8 characters as unsigned integers
 *     -------+---------+-----------------------------------------
 *       u    | String  | UU-encoded
 *     -------+---------+-----------------------------------------
 *       V    | Fixnum  | treat four characters as an unsigned
 *            |         | long in little-endian byte order
 *     -------+---------+-----------------------------------------
 *       v    | Fixnum  | treat two characters as an unsigned
 *            |         | short in little-endian byte order
 *     -------+---------+-----------------------------------------
 *       w    | Integer | BER-compressed integer (see Array.pack)
 *     -------+---------+-----------------------------------------
 *       X    | ---     | skip backward one character
 *     -------+---------+-----------------------------------------
 *       x    | ---     | skip forward one character
 *     -------+---------+-----------------------------------------
 *       Z    | String  | with trailing nulls removed
 *            |         | upto first null with *
 *     -------+---------+-----------------------------------------
 *       @    | ---     | skip to the offset given by the 
 *            |         | length argument
 *     -------+---------+-----------------------------------------
 */

static VALUE
pack_unpack(str, fmt)
    VALUE str, fmt;
{
    static char *hexdigits = "0123456789abcdef0123456789ABCDEFx";
    char *s, *send;
    char *p, *pend;
    VALUE ary;
    char type;
    long len;
    int tmp, star;
#ifdef NATINT_PACK
    int natint;                 /* native integer */
#endif

    StringValue(str);
    StringValue(fmt);
    s = RSTRING(str)->ptr;
    send = s + RSTRING(str)->len;
    p = RSTRING(fmt)->ptr;
    pend = p + RSTRING(fmt)->len;

    ary = rb_ary_new();
    while (p < pend) {
        type = *p++;
#ifdef NATINT_PACK
        natint = 0;
#endif

        if (ISSPACE(type)) continue;
        if (type == '#') {
            while ((p < pend) && (*p != '\n')) {
                p++;
            }
            continue;
        }
        star = 0;
        if (*p == '_' || *p == '!') {
            char *natstr = "sSiIlL";

            if (strchr(natstr, type)) {
#ifdef NATINT_PACK
                natint = 1;
#endif
                p++;
            }
            else {
                rb_raise(rb_eArgError, "'%c' allowed only after types %s", *p, natstr);
            }
        }
        if (p >= pend)
            len = 1;
        else if (*p == '*') {
            star = 1;
            len = send - s;
            p++;
        }
        else if (ISDIGIT(*p)) {
            len = strtoul(p, (char**)&p, 10);
        }
        else {
            len = (type != '@');
        }

        switch (type) {
          case '%':
            rb_raise(rb_eArgError, "%% is not supported");
            break;

          case 'A':
            if (len > send - s) len = send - s;
            {
                long end = len;
                char *t = s + len - 1;

                while (t >= s) {
                    if (*t != ' ' && *t != '\0') break;
                    t--; len--;
                }
                rb_ary_push(ary, infected_str_new(s, len, str));
                s += end;
            }
            break;

          case 'Z':
            {
                char *t = s;

                if (len > send-s) len = send-s;
                while (t < s+len && *t) t++;
                rb_ary_push(ary, infected_str_new(s, t-s, str));
                if (t < send) t++;
                s = star ? t : s+len;
            }
            break;

          case 'a':
            if (len > send - s) len = send - s;
            rb_ary_push(ary, infected_str_new(s, len, str));
            s += len;
            break;


          case 'b':
            {
                VALUE bitstr;
                char *t;
                int bits;
                long i;

                if (p[-1] == '*' || len > (send - s) * 8)
                    len = (send - s) * 8;
                bits = 0;
                rb_ary_push(ary, bitstr = rb_str_new(0, len));
                t = RSTRING(bitstr)->ptr;
                for (i=0; i<len; i++) {
                    if (i & 7) bits >>= 1;
                    else bits = *s++;
                    *t++ = (bits & 1) ? '1' : '0';
                }
            }
            break;

          case 'B':
            {
                VALUE bitstr;
                char *t;
                int bits;
                long i;

                if (p[-1] == '*' || len > (send - s) * 8)
                    len = (send - s) * 8;
                bits = 0;
                rb_ary_push(ary, bitstr = rb_str_new(0, len));
                t = RSTRING(bitstr)->ptr;
                for (i=0; i<len; i++) {
                    if (i & 7) bits <<= 1;
                    else bits = *s++;
                    *t++ = (bits & 128) ? '1' : '0';
                }
            }
            break;

          case 'h':
            {
                VALUE bitstr;
                char *t;
                int bits;
                long i;

                if (p[-1] == '*' || len > (send - s) * 2)
                    len = (send - s) * 2;
                bits = 0;
                rb_ary_push(ary, bitstr = rb_str_new(0, len));
                t = RSTRING(bitstr)->ptr;
                for (i=0; i<len; i++) {
                    if (i & 1)
                        bits >>= 4;
                    else
                        bits = *s++;
                    *t++ = hexdigits[bits & 15];
                }
            }
            break;

          case 'H':
            {
                VALUE bitstr;
                char *t;
                int bits;
                long i;

                if (p[-1] == '*' || len > (send - s) * 2)
                    len = (send - s) * 2;
                bits = 0;
                rb_ary_push(ary, bitstr = rb_str_new(0, len));
                t = RSTRING(bitstr)->ptr;
                for (i=0; i<len; i++) {
                    if (i & 1)
                        bits <<= 4;
                    else
                        bits = *s++;
                    *t++ = hexdigits[(bits >> 4) & 15];
                }
            }
            break;

          case 'c':
            PACK_LENGTH_ADJUST(char,sizeof(char));
            while (len-- > 0) {
                int c = *s++;
                if (c > (char)127) c-=256;
                rb_ary_push(ary, INT2FIX(c));
            }
            PACK_ITEM_ADJUST();
            break;

          case 'C':
            PACK_LENGTH_ADJUST(unsigned char,sizeof(unsigned char));
            while (len-- > 0) {
                unsigned char c = *s++;
                rb_ary_push(ary, INT2FIX(c));
            }
            PACK_ITEM_ADJUST();
            break;

          case 's':
            PACK_LENGTH_ADJUST(short,2);
            while (len-- > 0) {
                short tmp = 0;
                memcpy(OFF16(&tmp), s, NATINT_LEN(short,2));
                EXTEND16(tmp);
                s += NATINT_LEN(short,2);
                rb_ary_push(ary, INT2FIX(tmp));
            }
            PACK_ITEM_ADJUST();
            break;

          case 'S':
            PACK_LENGTH_ADJUST(unsigned short,2);
            while (len-- > 0) {
                unsigned short tmp = 0;
                memcpy(OFF16(&tmp), s, NATINT_LEN(unsigned short,2));
                s += NATINT_LEN(unsigned short,2);
                rb_ary_push(ary, INT2FIX(tmp));
            }
            PACK_ITEM_ADJUST();
            break;

          case 'i':
            PACK_LENGTH_ADJUST(int,sizeof(int));
            while (len-- > 0) {
                int tmp;
                memcpy(&tmp, s, sizeof(int));
                s += sizeof(int);
                rb_ary_push(ary, INT2NUM(tmp));
            }
            PACK_ITEM_ADJUST();
            break;

          case 'I':
            PACK_LENGTH_ADJUST(unsigned int,sizeof(unsigned int));
            while (len-- > 0) {
                unsigned int tmp;
                memcpy(&tmp, s, sizeof(unsigned int));
                s += sizeof(unsigned int);
                rb_ary_push(ary, UINT2NUM(tmp));
            }
            PACK_ITEM_ADJUST();
            brea