method

pack

v2_5_5 - Show latest stable - 0 notes - Class: Array

pack(p1, p2 = {}) public

Packs the contents of arr into a binary sequence according to the directives in aTemplateString (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 (“*”), all remaining array elements will be converted. Any of the directives “sSiIlL” may be followed by an underscore (“_”) or exclamation mark (“!”) 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 String#unpack.

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"

If aBufferString is specified and its capacity is enough, pack uses it as the buffer and returns it. When the offset is specified by the beginning of aTemplateString, the result is filled after the offset. If original contents of aBufferString exists and it’s longer than the offset, the rest of offsetOfBuffer are overwritten by the result. If it’s shorter, the gap is filled with “0”.

Note that “buffer:” option does not guarantee not to allocate memory in pack. If the capacity of aBufferString is not enough, pack allocates memory.

Directives for pack.

Integer       | Array   |
Directive     | Element | Meaning
----------------------------------------------------------------------------
C             | Integer | 8-bit unsigned (unsigned char)
S             | Integer | 16-bit unsigned, native endian (uint16_t)
L             | Integer | 32-bit unsigned, native endian (uint32_t)
Q             | Integer | 64-bit unsigned, native endian (uint64_t)
J             | Integer | pointer width unsigned, native endian (uintptr_t)
              |         | (J is available since Ruby 2.3.)
              |         |
c             | Integer | 8-bit signed (signed char)
s             | Integer | 16-bit signed, native endian (int16_t)
l             | Integer | 32-bit signed, native endian (int32_t)
q             | Integer | 64-bit signed, native endian (int64_t)
j             | Integer | pointer width signed, native endian (intptr_t)
              |         | (j is available since Ruby 2.3.)
              |         |
S_ S!         | Integer | unsigned short, native endian
I I_ I!       | Integer | unsigned int, native endian
L_ L!         | Integer | unsigned long, native endian
Q_ Q!         | Integer | unsigned long long, native endian (ArgumentError
              |         | if the platform has no long long type.)
              |         | (Q_ and Q! is available since Ruby 2.1.)
J!            | Integer | uintptr_t, native endian (same with J)
              |         | (J! is available since Ruby 2.3.)
              |         |
s_ s!         | Integer | signed short, native endian
i i_ i!       | Integer | signed int, native endian
l_ l!         | Integer | signed long, native endian
q_ q!         | Integer | signed long long, native endian (ArgumentError
              |         | if the platform has no long long type.)
              |         | (q_ and q! is available since Ruby 2.1.)
j!            | Integer | intptr_t, native endian (same with j)
              |         | (j! is available since Ruby 2.3.)
              |         |
S> s> S!> s!> | Integer | same as the directives without ">" except
L> l> L!> l!> |         | big endian
I!> i!>       |         | (available since Ruby 1.9.3)
Q> q> Q!> q!> |         | "S>" is same as "n"
J> j> J!> j!> |         | "L>" is same as "N"
              |         |
S< s< S!< s!< | Integer | same as the directives without "<" except
L< l< L!< l!< |         | little endian
I!< i!<       |         | (available since Ruby 1.9.3)
Q< q< Q!< q!< |         | "S<" is same as "v"
J< j< J!< j!< |         | "L<" is same as "V"
              |         |
n             | Integer | 16-bit unsigned, network (big-endian) byte order
N             | Integer | 32-bit unsigned, network (big-endian) byte order
v             | Integer | 16-bit unsigned, VAX (little-endian) byte order
V             | Integer | 32-bit unsigned, VAX (little-endian) byte order
              |         |
U             | Integer | UTF-8 character
w             | Integer | BER-compressed integer

Float        | Array   |
Directive    | Element | Meaning
---------------------------------------------------------------------------
D d          | Float   | double-precision, native format
F f          | Float   | single-precision, native format
E            | Float   | double-precision, little-endian byte order
e            | Float   | single-precision, little-endian byte order
G            | Float   | double-precision, network (big-endian) byte order
g            | Float   | single-precision, network (big-endian) byte order

String       | Array   |
Directive    | Element | Meaning
---------------------------------------------------------------------------
A            | String  | arbitrary binary string (space padded, count is width)
a            | String  | arbitrary binary string (null padded, count is width)
Z            | String  | same as ``a'', except that null is added with *
B            | String  | bit string (MSB first)
b            | String  | bit string (LSB first)
H            | String  | hex string (high nibble first)
h            | String  | hex string (low nibble first)
u            | String  | UU-encoded string
M            | String  | quoted printable, MIME encoding (see RFC2045)
m            | String  | base64 encoded string (see RFC 2045, count is width)
             |         | (if count is 0, no line feed are added, see RFC 4648)
P            | String  | pointer to a structure (fixed-length string)
p            | String  | pointer to a null-terminated string

Misc.        | Array   |
Directive    | Element | Meaning
---------------------------------------------------------------------------
@            | ---     | moves to absolute position
X            | ---     | back up a byte
x            | ---     | null byte

Show source

static VALUE
pack_pack(int argc, VALUE *argv, VALUE ary)
{
    static const char nul10[] = "\0\0\0\0\0\0\0\0\0\0";
    static const char spc10[] = "          ";
    const char *p, *pend;
    VALUE fmt, opt = Qnil, res, from, associates = 0, buffer = 0;
    char type;
    long len, idx, plen;
    const char *ptr;
    int enc_info = 1;           /* 0 - BINARY, 1 - US-ASCII, 2 - UTF-8 */
#ifdef NATINT_PACK
    int natint;         /* native integer */
#endif
    int integer_size, bigendian_p;

    rb_scan_args(argc, argv, "10:", &fmt, &opt);

    StringValue(fmt);
    p = RSTRING_PTR(fmt);
    pend = p + RSTRING_LEN(fmt);
    if (!NIL_P(opt)) {
        static ID keyword_ids[1];
        if (!keyword_ids[0])
            CONST_ID(keyword_ids[0], "buffer");

        rb_get_kwargs(opt, keyword_ids, 0, 1, &buffer);

        if (buffer != Qundef && !RB_TYPE_P(buffer, T_STRING))
            rb_raise(rb_eTypeError, "buffer must be String, not %s", rb_obj_classname(buffer));
    }
    if (buffer)
        res = buffer;
    else
        res = rb_str_buf_new(0);

    idx = 0;

#define TOO_FEW (rb_raise(rb_eArgError, toofew), 0)
#define MORE_ITEM (idx < RARRAY_LEN(ary))
#define THISFROM (MORE_ITEM ? RARRAY_AREF(ary, idx) : TOO_FEW)
#define NEXTFROM (MORE_ITEM ? RARRAY_AREF(ary, idx++) : TOO_FEW)

    while (p < pend) {
        int explicit_endian = 0;
        if (RSTRING_PTR(fmt) + RSTRING_LEN(fmt) != 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;
        }

        {
          modifiers:
            switch (*p) {
              case '_':
              case '!':
                if (strchr(natstr, type)) {
#ifdef NATINT_PACK
                    natint = 1;
#endif
                    p++;
                }
                else {
                    rb_raise(rb_eArgError, "'%c' allowed only after types %s", *p, natstr);
                }
                goto modifiers;

              case '<':
              case '>':
                if (!strchr(endstr, type)) {
                    rb_raise(rb_eArgError, "'%c' allowed only after types %s", *p, endstr);
                }
                if (explicit_endian) {
                    rb_raise(rb_eRangeError, "Can't use both '<' and '>'");
                }
                explicit_endian = *p++;
                goto modifiers;
            }
        }

        if (*p == '*') {       /* set data length */
            len = strchr("@Xxu", type) ? 0
                : strchr("PMm", type) ? 1
                : RARRAY_LEN(ary) - idx;
            p++;
        }
        else if (ISDIGIT(*p)) {
            errno = 0;
            len = STRTOUL(p, (char**)&p, 10);
            if (errno) {
                rb_raise(rb_eRangeError, "pack length too big");
            }
        }
        else {
            len = 1;
        }

        switch (type) {
          case 'U':
            /* if encoding is US-ASCII, upgrade to UTF-8 */
            if (enc_info == 1) enc_info = 2;
            break;
          case 'm': case 'M': case 'u':
            /* keep US-ASCII (do nothing) */
            break;
          default:
            /* fall back to BINARY */
            enc_info = 0;
            break;
        }
        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_PTR(from);
                plen = RSTRING_LEN(from);
                OBJ_INFECT(res, from);
            }

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

            switch (type) {
              case 'a':                /* arbitrary binary string (null padded)  */
              case 'A':         /* arbitrary binary string (ASCII space padded) */
              case 'Z':         /* null terminated 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;

#define castchar(from) (char)((from) & 0xff)

              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 = castchar(byte);
                            rb_str_buf_cat(res, &c, 1);
                            byte = 0;
                        }
                    }
                    if (len & 7) {
                        char c;
                        byte >>= 7 - (len & 7);
                        c = castchar(byte);
                        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 = castchar(byte);
                            rb_str_buf_cat(res, &c, 1);
                            byte = 0;
                        }
                    }
                    if (len & 7) {
                        char c;
                        byte <<= 7 - (len & 7);
                        c = castchar(byte);
                        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 + 1) / 2 - (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 = castchar(byte);
                            rb_str_buf_cat(res, &c, 1);
                            byte = 0;
                        }
                    }
                    if (len & 1) {
                        char c = castchar(byte);
                        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 + 1) / 2 - (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 = castchar(byte);
                            rb_str_buf_cat(res, &c, 1);
                            byte = 0;
                        }
                    }
                    if (len & 1) {
                        char c = castchar(byte);
                        rb_str_buf_cat(res, &c, 1);
                    }
                    len = j;
                    goto grow;
                }
                break;
            }
            break;

          case 'c':            /* signed char */
          case 'C':            /* unsigned char */
            integer_size = 1;
            bigendian_p = BIGENDIAN_P(); /* not effective */
            goto pack_integer;

          case 's':            /* s for int16_t, s! for signed short */
            integer_size = NATINT_LEN(short, 2);
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'S':            /* S for uint16_t, S! for unsigned short */
            integer_size = NATINT_LEN(short, 2);
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'i':            /* i and i! for signed int */
            integer_size = (int)sizeof(int);
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'I':            /* I and I! for unsigned int */
            integer_size = (int)sizeof(int);
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'l':            /* l for int32_t, l! for signed long */
            integer_size = NATINT_LEN(long, 4);
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'L':            /* L for uint32_t, L! for unsigned long */
            integer_size = NATINT_LEN(long, 4);
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'q':            /* q for int64_t, q! for signed long long */
            integer_size = NATINT_LEN_Q;
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'Q':            /* Q for uint64_t, Q! for unsigned long long */
            integer_size = NATINT_LEN_Q;
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'j':            /* j for intptr_t */
            integer_size = sizeof(intptr_t);
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'J':            /* J for uintptr_t */
            integer_size = sizeof(uintptr_t);
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'n':            /* 16 bit (2 bytes) integer (network byte-order)  */
            integer_size = 2;
            bigendian_p = 1;
            goto pack_integer;

          case 'N':            /* 32 bit (4 bytes) integer (network byte-order) */
            integer_size = 4;
            bigendian_p = 1;
            goto pack_integer;

          case 'v':            /* 16 bit (2 bytes) integer (VAX byte-order) */
            integer_size = 2;
            bigendian_p = 0;
            goto pack_integer;

          case 'V':            /* 32 bit (4 bytes) integer (VAX byte-order) */
            integer_size = 4;
            bigendian_p = 0;
            goto pack_integer;

          pack_integer:
            if (explicit_endian) {
                bigendian_p = explicit_endian == '>';
            }
            if (integer_size > MAX_INTEGER_PACK_SIZE)
                rb_bug("unexpected intger size for pack: %d", integer_size);
            while (len-- > 0) {
                char intbuf[MAX_INTEGER_PACK_SIZE];

                from = NEXTFROM;
                rb_integer_pack(from, intbuf, integer_size, 1, 0,
                    INTEGER_PACK_2COMP |
                    (bigendian_p ? INTEGER_PACK_BIG_ENDIAN : INTEGER_PACK_LITTLE_ENDIAN));
                rb_str_buf_cat(res, intbuf, integer_size);
            }
            break;

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

                from = NEXTFROM;
                f = (float)RFLOAT_VALUE(rb_to_float(from));
                rb_str_buf_cat(res, (char*)&f, sizeof(float));
            }
            break;

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

                from = NEXTFROM;
                tmp.f = (float)RFLOAT_VALUE(rb_to_float(from));
                HTOVF(tmp);
                rb_str_buf_cat(res, tmp.buf, sizeof(float));
            }
            break;

          case 'E':            /* double precision float in VAX byte-order */
            while (len-- > 0) {
                DOUBLE_CONVWITH(tmp);
                from = NEXTFROM;
                tmp.d = RFLOAT_VALUE(rb_to_float(from));
                HTOVD(tmp);
                rb_str_buf_cat(res, tmp.buf, sizeof(double));
            }
            break;

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

                from = NEXTFROM;
                d = RFLOAT_VALUE(rb_to_float(from));
                rb_str_buf_cat(res, (char*)&d, sizeof(double));
            }
            break;

          case 'g':            /* single precision float in network byte-order */
            while (len-- > 0) {
                FLOAT_CONVWITH(tmp);
                from = NEXTFROM;
                tmp.f = (float)RFLOAT_VALUE(rb_to_float(from));
                HTONF(tmp);
                rb_str_buf_cat(res, tmp.buf, sizeof(float));
            }
            break;

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

                from = NEXTFROM;
                tmp.d = RFLOAT_VALUE(rb_to_float(from));
                HTOND(tmp);
                rb_str_buf_cat(res, tmp.buf, 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_LEN(res);
            if (plen < len)
                rb_raise(rb_eArgError, "X outside of string");
            rb_str_set_len(res, plen - len);
            break;

          case '@':            /* null fill to absolute position */
            len -= RSTRING_LEN(res);
            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) {
                SIGNED_VALUE l;
                char buf[8];
                int le;

                from = NEXTFROM;
                from = rb_to_int(from);
                l = NUM2LONG(from);
                if (l < 0) {
                    rb_raise(rb_eRangeError, "pack(U): value out of range");
                }
                le = rb_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_PTR(from);
            plen = RSTRING_LEN(from);
            OBJ_INFECT(res, from);

            if (len == 0 && type == 'm') {
                encodes(res, ptr, plen, type, 0);
                ptr += plen;
                break;
            }
            if (len <= 2)
                len = 45;
            else if (len > 63 && type == 'u')
                len = 63;
            else
                len = len / 3 * 3;
            while (plen > 0) {
                long todo;

                if (plen > len)
                    todo = len;
                else
                    todo = plen;
                encodes(res, ptr, todo, type, 1);
                plen -= todo;
                ptr += todo;
            }
            break;

          case 'M':            /* quoted-printable encoded string */
            from = rb_obj_as_string(NEXTFROM);
            OBJ_INFECT(res, from);
            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_LEN(from) < len) {
                    rb_raise(rb_eArgError, "too short buffer for P(%ld for %ld)",
                             RSTRING_LEN(from), 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);
                    OBJ_INFECT(res, from);
                    rb_obj_taint(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) {
                VALUE buf = rb_str_new(0, 0);
                size_t numbytes;
                int sign;
                char *cp;

                from = NEXTFROM;
                from = rb_to_int(from);
                numbytes = rb_absint_numwords(from, 7, NULL);
                if (numbytes == 0)
                    numbytes = 1;
                buf = rb_str_new(NULL, numbytes);

                sign = rb_integer_pack(from, RSTRING_PTR(buf), RSTRING_LEN(buf), 1, 1, INTEGER_PACK_BIG_ENDIAN);

                if (sign < 0)
                    rb_raise(rb_eArgError, "can't compress negative numbers");
                if (sign == 2)
                    rb_bug("buffer size problem?");

                cp = RSTRING_PTR(buf);
                while (1 < numbytes) {
                  *cp |= 0x80;
                  cp++;
                  numbytes--;
                }

                rb_str_buf_cat(res, RSTRING_PTR(buf), RSTRING_LEN(buf));
            }
            break;

          default: {
            char unknown[5];
            if (ISPRINT(type)) {
                unknown[0] = type;
                unknown[1] = '\0';
            }
            else {
                snprintf(unknown, sizeof(unknown), "\\x%.2x", type & 0xff);
            }
            rb_warning("unknown pack directive '%s' in '% "PRIsVALUE"'",
                       unknown, fmt);
            break;
          }
        }
    }

    if (associates) {
        str_associate(res, associates);
    }
    OBJ_INFECT(res, fmt);
    switch (enc_info) {
      case 1:
        ENCODING_CODERANGE_SET(res, rb_usascii_encindex(), ENC_CODERANGE_7BIT);
        break;
      case 2:
        rb_enc_set_index(res, rb_utf8_encindex());
        break;
      default:
        /* do nothing, keep ASCII-8BIT */
        break;
    }
    return res;
}

pack

Related methods