#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"

// C99 required

enum {
  // ASN_TAG
  ASN_BOOLEAN           = 0x01,
  ASN_INTEGER32         = 0x02,
  ASN_BIT_STRING        = 0x03,
  ASN_OCTET_STRING      = 0x04,
  ASN_NULL              = 0x05,
  ASN_OBJECT_IDENTIFIER = 0x06,
  ASN_OID               = 0x06, //X
  ASN_OBJECT_DESCRIPTOR = 0x07, //X
  ASN_EXTERNAL          = 0x08, //X
  ASN_REAL              = 0x09, //X
  ASN_ENUMERATED        = 0x0a, //X
  ASN_EMBEDDED_PDV      = 0x0b, //X
  ASN_UTF8_STRING       = 0x0c, //X
  ASN_RELATIVE_OID      = 0x0d, //X
  ASN_SEQUENCE          = 0x10,
  ASN_SET               = 0x11, //X
  ASN_NUMERIC_STRING    = 0x12, //X
  ASN_PRINTABLE_STRING  = 0x13, //X
  ASN_TELETEX_STRING    = 0x14, //X
  ASN_T61_STRING        = 0x14, //X
  ASN_VIDEOTEX_STRING   = 0x15, //X
  ASN_IA5_STRING        = 0x16, //X
  ASN_ASCII_STRING      = 0x16, //X
  ASN_UTC_TIME          = 0x17, //X
  ASN_GENERALIZED_TIME  = 0x18, //X
  ASN_GRAPHIC_STRING    = 0x19, //X
  ASN_VISIBLE_STRING    = 0x1a, //X
  ASN_ISO646_STRING     = 0x1a, //X
  ASN_GENERAL_STRING    = 0x1b, //X
  ASN_UNIVERSAL_STRING  = 0x1c, //X
  ASN_CHARACTER_STRING  = 0x1d, //X
  ASN_BMPSTRING         = 0x1e, //X

  ASN_TAG_BER           = 0x1f,
  ASN_TAG_MASK          = 0x1f,

  // primitive/constructed
  ASN_CONSTRUCTED       = 0x20,

  // ASN_CLASS
  ASN_UNIVERSAL         = 0x00,
  ASN_APPLICATION       = 0x40,
  ASN_CONTEXT           = 0x80,
  ASN_PRIVATE           = 0xc0,

  ASN_CLASS_MASK        = 0xc0,
  ASN_CLASS_SHIFT       = 6,

  // ASN_APPLICATION SNMP
  SNMP_IPADDRESS         = 0x00,
  SNMP_COUNTER32         = 0x01,
  SNMP_UNSIGNED32        = 0x02,
  SNMP_TIMETICKS         = 0x03,
  SNMP_OPAQUE            = 0x04,
  SNMP_COUNTER64         = 0x06,
};

enum {
  BER_CLASS       = 0,
  BER_TAG         = 1,
  BER_CONSTRUCTED = 2,
  BER_DATA        = 3,
  BER_ARRAYSIZE
};

#define MAX_OID_STRLEN 4096

static SV *buf_sv; // encoding buffer
static U8 *buf, *cur, *end; // buffer start, current, end

#if __GNUC__ >= 3
# define expect(expr,value)         __builtin_expect ((expr), (value))
# define INLINE                     static inline
#else
# define expect(expr,value)         (expr)
# define INLINE                     static
#endif

#define expect_false(expr) expect ((expr) != 0, 0)
#define expect_true(expr)  expect ((expr) != 0, 1)

// for "small" integers, return a readonly sv, otherwise create a new one
static SV *newSVcacheint (int val)
{
  static SV *cache[32];

  if (expect_false (val < 0 || val >= sizeof (cache)))
    return newSViv (val);

  if (expect_false (!cache [val]))
    {
      cache [val] = newSVuv (val);
      SvREADONLY_on (cache [val]);
    }

  return SvREFCNT_inc_NN (cache [val]);
}

/////////////////////////////////////////////////////////////////////////////
// decoder

static void
error (const char *errmsg)
{
  croak ("%s at offset 0x%04x", errmsg, cur - buf);
}

static void
want (UV count)
{
  if (expect_false ((uintptr_t)(end - cur) < count))
    error ("unexpected end of message buffer");
}

// get_* functions fetch something from the buffer
// decode_* functions use get_* fun ctions to decode ber values

// get n octets
static U8 *
get_n (UV count)
{
  want (count);
  U8 *res = cur;
  cur += count;
  return res;
}

// get single octet
static U8
get_u8 (void)
{
  if (cur == end)
    error ("unexpected end of message buffer");

  return *cur++;
}

// get ber-encoded integer (i.e. pack "w")
static U32
get_w (void)
{
  U32 res = 0;

  for (;;)
    {
      U8 c = get_u8 ();
      res = (res << 7) | (c & 0x7f);

      if (!(c & 0x80))
        return res;
    }
}

static U32
get_length (void)
{
  U32 res = get_u8 ();

  if (res & 0x80)
    {
      int cnt = res & 0x7f;
      res = 0;

      switch (cnt)
        {
          case 0:
            error ("indefinite ASN.1 lengths not supported");
            return 0;

          default:
            error ("ASN.1 length too long");
            return 0;

          case 4: res = (res << 8) | get_u8 ();
          case 3: res = (res << 8) | get_u8 ();
          case 2: res = (res << 8) | get_u8 ();
          case 1: res = (res << 8) | get_u8 ();
        }
    }

  return res;
}

static U32
get_integer32 (void)
{
  U32 length = get_length ();

  if (length <= 0)
    {
      error ("INTEGER32 length equal to zero");
      return 0;
    }

  U8 *data = get_n (length);

  if (length > 5 || (length > 4 && data [0]))
    {
      error ("INTEGER32 length too long");
      return 0;
    }

  U32 res = data [0] & 0x80 ? 0xffffffff : 0;

  while (length--)
    res = (res << 8) | *data++;

  return res;
}

static SV *
decode_integer32 (void)
{
  return newSViv ((I32)get_integer32 ());
}

static SV *
decode_unsigned32 (void)
{
  return newSVuv ((U32)get_integer32 ());
}

#if IVSIZE >= 8

static U64TYPE
get_integer64 (void)
{
  U32 length = get_length ();

  if (length <= 0)
    {
      error ("INTEGER64 length equal to zero");
      return 0;
    }

  U8 *data = get_n (length);

  if (length > 9 || (length > 8 && data [0]))
    {
      error ("INTEGER64 length too long");
      return 0;
    }

  U64TYPE res = data [0] & 0x80 ? 0xffffffffffffffff : 0;

  while (length--)
    res = (res << 8) | *data++;

  return res;
}

static SV *
decode_integer64 (void)
{
  return newSViv ((I64TYPE)get_integer64 ());
}

static SV *
decode_unsigned64 (void)
{
  return newSVuv ((U64TYPE)get_integer64 ());
}

#endif

static SV *
decode_octet_string (void)
{
  U32 length = get_length ();
  U8 *data = get_n (length);
  return newSVpvn (data, length);
}

// gelper for decode_object_identifier
static char *
write_uv (char *buf, U32 u)
{
  // the one-digit case is absolutely predominant, so this pays off (hopefully)
  if (u < 10)
    *buf++ = u + '0';
  else
    {
      char *beg = buf;

      do
        {
          *buf++ = u % 10 + '0';
          u /= 10;
        }
      while (u);

      // reverse digits
      for (char *ptr = buf; --ptr != beg; ++beg)
        {
          char c = *ptr;
          *ptr = *beg;
          *beg = c;
        }
    }

  return buf;
}

static SV *
decode_object_identifier (void)
{
  U32 length = get_length ();

  if (length <= 0)
    {
      error ("OBJECT IDENTIFIER length equal to zero");
      return &PL_sv_undef;
    }

  U8 *end = cur + length;
  U32 w = get_w ();

  static char oid[MAX_OID_STRLEN]; // must be static
  char *app = oid;

  app = write_uv (app, (U8)w / 40);
  *app++ = '.';
  app = write_uv (app, (U8)w % 40);

  // we assume an oid component is never > 64 bytes
  while (cur < end && oid + sizeof (oid) - app > 64)
    {
      w = get_w ();
      *app++ = '.';
      app = write_uv (app, w);
    }

  return newSVpvn (oid, app - oid);
}

static SV *
decode_ber ()
{
  int identifier = get_u8 ();

  SV *res;

  int constructed = identifier & ASN_CONSTRUCTED;
  int klass       = identifier & ASN_CLASS_MASK;
  int tag         = identifier & ASN_TAG_MASK;

  if (tag == ASN_TAG_BER)
    tag = get_w ();

  if (tag == ASN_TAG_BER)
    tag = get_w ();

  if (constructed)
    {
      U32 len = get_length ();
      U32 seqend = (cur - buf) + len;
      AV *av = (AV *)sv_2mortal ((SV *)newAV ());

      while (cur < buf + seqend)
        av_push (av, decode_ber ());

      if (cur > buf + seqend)
        croak ("constructed type %02x overflow (%x %x)\n", identifier, cur - buf, seqend);

      res = newRV_inc ((SV *)av);
    }
  else
    switch (identifier)
      {
        case ASN_NULL:
          res = &PL_sv_undef;
          break;

        case ASN_OBJECT_IDENTIFIER:
          res = decode_object_identifier ();
          break;

        case ASN_INTEGER32:
          res = decode_integer32 ();
          break;

        case ASN_APPLICATION | SNMP_UNSIGNED32:
        case ASN_APPLICATION | SNMP_COUNTER32:
        case ASN_APPLICATION | SNMP_TIMETICKS:
          res = decode_unsigned32 ();
          break;

#if 0 // handled by default case
        case ASN_OCTET_STRING:
        case ASN_APPLICATION | ASN_IPADDRESS:
        case ASN_APPLICATION | ASN_OPAQUE:
          res = decode_octet_string ();
          break;
#endif

        case ASN_APPLICATION | SNMP_COUNTER64:
          res = decode_integer64 ();
          break;

        default:
          res = decode_octet_string ();
          break;
      }

  AV *av = newAV ();
  av_fill (av, BER_ARRAYSIZE - 1);
  AvARRAY (av)[BER_CLASS      ] = newSVcacheint (klass >> ASN_CLASS_SHIFT);
  AvARRAY (av)[BER_TAG        ] = newSVcacheint (tag);
  AvARRAY (av)[BER_CONSTRUCTED] = newSVcacheint (constructed ? 1 : 0);
  AvARRAY (av)[BER_DATA       ] = res;

  return newRV_noinc ((SV *)av);
}

/////////////////////////////////////////////////////////////////////////////
// encoder

/* adds two STRLENs together, slow, and with paranoia */
static STRLEN
strlen_sum (STRLEN l1, STRLEN l2)
{
  size_t sum = l1 + l2;

  if (sum < (size_t)l2 || sum != (size_t)(STRLEN)sum)
    croak ("JSON::XS: string size overflow");

  return sum;
}

static void
set_buf (SV *sv)
{
  STRLEN len;
  buf_sv = sv;
  buf = SvPVbyte (buf_sv, len);
  cur = buf;
  end = buf + len;
}

/* similar to SvGROW, but somewhat safer and guarantees exponential realloc strategy */
static char *
my_sv_grow (SV *sv, size_t len1, size_t len2)
{
  len1 = strlen_sum (len1, len2);
  len1 = strlen_sum (len1, len1 >> 1);

  if (len1 > 4096 - 24)
    len1 = (len1 | 4095) - 24;

  return SvGROW (sv, len1);
}

static void
need (STRLEN len)
{
  if (expect_false ((uintptr_t)(end - cur) < len))
    {
      STRLEN pos = cur - buf;
      buf = my_sv_grow (buf_sv, pos, len);
      cur = buf + pos;
      end = buf + SvLEN (buf_sv) - 1;
    }
}

static void
put_u8 (int val)
{
  need (1);
  *cur++ = val;
}

static void
put_w_nocheck (U32 val)
{
  *cur = (val >> 7 * 4) | 0x80; cur += val >= (1 << (7 * 4));
  *cur = (val >> 7 * 3) | 0x80; cur += val >= (1 << (7 * 3));
  *cur = (val >> 7 * 2) | 0x80; cur += val >= (1 << (7 * 2));
  *cur = (val >> 7 * 1) | 0x80; cur += val >= (1 << (7 * 1));
  *cur =  val           & 0x7f; cur += 1;
}

static void
put_w (U32 val)
{
  need (5); // we only handle up to 5 bytes

  put_w_nocheck (val);
}

static U8 *
put_length_at (U32 val, U8 *cur)
{
  if (val < 0x7fU)
    *cur++ = val;
  else
    {
      U8 *lenb = cur++;

      *cur = val >> 24; cur += *cur > 0;
      *cur = val >> 16; cur += *cur > 0;
      *cur = val >>  8; cur += *cur > 0;
      *cur = val      ; cur += 1;

      *lenb = 0x80 + cur - lenb - 1;
    }

  return cur;
}

static void
put_length (U32 val)
{
  need (5);
  cur = put_length_at (val, cur);
}

// return how many bytes the encoded length requires
static int length_length (U32 val)
{
  return val < 0x7fU
    ? 1
    : 2 + (val > 0xffU) + (val > 0xffffU) + (val > 0xffffffU);
}

static void
encode_octet_string (SV *sv)
{
  STRLEN len;
  char *ptr = SvPVbyte (sv, len);

  put_length (len);
  need (len);
  memcpy (cur, ptr, len);
  cur += len;
}

static void
encode_integer32 (IV iv)
{
  need (5);

  U8 *lenb = cur++;

  if (iv < 0)
    {
      // get two's complement bit pattern - works even on hypthetical non-2c machines
      U32 uv = iv;

      *cur = uv >> 24; cur += !!(~uv & 0xff800000U);
      *cur = uv >> 16; cur += !!(~uv & 0xffff8000U);
      *cur = uv >>  8; cur += !!(~uv & 0xffffff80U);
      *cur = uv      ; cur += 1;
    }
  else
    {
      *cur = iv >> 24; cur += *cur > 0;
      *cur = iv >> 16; cur += *cur > 0;
      *cur = iv >>  8; cur += *cur > 0;
      *cur = iv      ; cur += 1;
    }

  *lenb = cur - lenb - 1;
}

static void
encode_unsigned64 (U64TYPE uv)
{
  need (9);

  U8 *lenb = cur++;

  *cur = uv >> 56; cur += *cur > 0;
  *cur = uv >> 48; cur += *cur > 0;
  *cur = uv >> 40; cur += *cur > 0;
  *cur = uv >> 32; cur += *cur > 0;
  *cur = uv >> 24; cur += *cur > 0;
  *cur = uv >> 16; cur += *cur > 0;
  *cur = uv >>  8; cur += *cur > 0;
  *cur = uv      ; cur += 1;

  *lenb = cur - lenb - 1;
}

// we don't know the length yet, so we optimistically
// assume the length will need one octet later. if that
// turns out to be wrong, we memove as needed.
// mark the beginning
static STRLEN
len_fixup_mark ()
{
  return cur++ - buf;
}

// patch up the length
static void
len_fixup (STRLEN mark)
{
  STRLEN reallen = (cur - buf) - mark - 1;
  int lenlen = length_length (reallen);

  if (expect_false (lenlen > 1))
    {
      // bad luck, we have to shift the bytes to make room for the length
      need (5);
      memmove (buf + mark + lenlen, buf + mark + 1, reallen);
      cur += lenlen - 1;
    }
  
  put_length_at (reallen, buf + mark);
}

static char *
read_uv (char *str, UV *uv)
{
  UV r = 0;

  while (*str >= '0')
    r = r * 10 + *str++ - '0';

  *uv = r;

  str += !!*str; // advance over any non-zero byte

  return str;
}

static void
encode_object_identifier (SV *oid)
{
  STRLEN slen;
  char *ptr = SvPV (oid, slen); // utf8 vs. bytes does not matter

  // we need at most as many octets as the string form
  need (slen + 1);
  STRLEN mark = len_fixup_mark ();

  UV w1, w2;

  ptr = read_uv (ptr, &w1);
  ptr = read_uv (ptr, &w2);

  put_w_nocheck (w1 * 40 + w2);

  while (*ptr)
    {
      ptr = read_uv (ptr, &w1);
      put_w_nocheck (w1);
    }

  len_fixup (mark);
}

// checkl whether an SV is a BER tuple and returns its AV *
static AV *
ber_tuple (SV *tuple)
{
  SV *rv;

  if (expect_false (!SvROK (tuple) || SvTYPE ((rv = SvRV (tuple))) != SVt_PVAV))
    croak ("BER tuple must be array-reference");

  if (expect_false (SvRMAGICAL (rv)))
    croak ("BER tuple must not be tied");

  if (expect_false (AvFILL ((AV *)rv) != BER_ARRAYSIZE - 1))
    croak ("BER tuple must contain exactly %d elements, not %d", BER_ARRAYSIZE, AvFILL ((AV *)rv) + 1);

  return (AV *)rv;
}

static void
encode_ber (SV *tuple)
{
  AV *av = ber_tuple (tuple);

  int klass       = SvIV (AvARRAY (av)[BER_CLASS]);
  int tag         = SvIV (AvARRAY (av)[BER_TAG]);
  int constructed = SvIV (AvARRAY (av)[BER_CONSTRUCTED]) ? ASN_CONSTRUCTED : 0;
  SV *data        =       AvARRAY (av)[BER_DATA];

  int identifier = (klass << ASN_CLASS_SHIFT) | constructed;

  if (expect_false (tag >= ASN_TAG_BER))
    {
      put_u8 (identifier | ASN_TAG_BER);
      put_w (tag);
    }
  else
    put_u8 (identifier | tag);

  if (constructed)
    {
      // we optimistically assume that only one length byte is needed
      // and adjust later
      need (1);
      STRLEN mark = len_fixup_mark ();

      if (expect_false (!SvROK (data) || SvTYPE (SvRV (data)) != SVt_PVAV))
        croak ("BER constructed data must be array-reference");

      AV *av = (AV *)SvRV (data);
      int fill = AvFILL (av);

      if (expect_false (SvRMAGICAL (av)))
        croak ("BER constructed data must not be tied");

      for (int i = 0; i <= fill; ++i)
        encode_ber (AvARRAY (av)[i]);

      len_fixup (mark);
    }
  else
    switch (identifier | tag)
      {
        case ASN_NULL:
          put_length (0);
          break;

        case ASN_OBJECT_IDENTIFIER:
          encode_object_identifier (data);
          break;

        case ASN_INTEGER32:
          encode_integer32 (SvIV (data));
          break;

        case ASN_APPLICATION | SNMP_UNSIGNED32:
        case ASN_APPLICATION | SNMP_COUNTER32:
        case ASN_APPLICATION | SNMP_TIMETICKS:
        case ASN_APPLICATION | SNMP_COUNTER64:
          encode_unsigned64 (SvUV (data));
          break;

        default:
          encode_octet_string (data);
          break;
      }

}

/////////////////////////////////////////////////////////////////////////////

MODULE = Convert::BER::XS		PACKAGE = Convert::BER::XS

PROTOTYPES: ENABLE

BOOT:
{
  HV *stash = gv_stashpv ("Convert::BER::XS", 1);

  static const struct {
    const char *name;
    IV iv;
  } *civ, const_iv[] = {
    { "ASN_BOOLEAN",           ASN_BOOLEAN           },
    { "ASN_INTEGER32",         ASN_INTEGER32         },
    { "ASN_BIT_STRING",        ASN_BIT_STRING        },
    { "ASN_OCTET_STRING",      ASN_OCTET_STRING      },
    { "ASN_NULL",              ASN_NULL              },
    { "ASN_OBJECT_IDENTIFIER", ASN_OBJECT_IDENTIFIER },
    { "ASN_TAG_BER",           ASN_TAG_BER           },
    { "ASN_TAG_MASK",          ASN_TAG_MASK          },
    { "ASN_CONSTRUCTED",       ASN_CONSTRUCTED       },
    { "ASN_UNIVERSAL",         ASN_UNIVERSAL   >> ASN_CLASS_SHIFT },
    { "ASN_APPLICATION",       ASN_APPLICATION >> ASN_CLASS_SHIFT },
    { "ASN_CONTEXT",           ASN_CONTEXT     >> ASN_CLASS_SHIFT },
    { "ASN_PRIVATE",           ASN_PRIVATE     >> ASN_CLASS_SHIFT },
    { "ASN_CLASS_MASK",        ASN_CLASS_MASK        },
    { "ASN_CLASS_SHIFT",       ASN_CLASS_SHIFT       },
    { "ASN_SEQUENCE",          ASN_SEQUENCE          },
    { "SNMP_IPADDRESS",        SNMP_IPADDRESS        },
    { "SNMP_COUNTER32",        SNMP_COUNTER32        },
    { "SNMP_UNSIGNED32",       SNMP_UNSIGNED32       },
    { "SNMP_TIMETICKS",        SNMP_TIMETICKS        },
    { "SNMP_OPAQUE",           SNMP_OPAQUE           },
    { "SNMP_COUNTER64",        SNMP_COUNTER64        },

    { "BER_CLASS"      , BER_CLASS       },
    { "BER_TAG"        , BER_TAG         },
    { "BER_CONSTRUCTED", BER_CONSTRUCTED },
    { "BER_DATA"       , BER_DATA        },
  };

  for (civ = const_iv + sizeof (const_iv) / sizeof (const_iv [0]); civ > const_iv; civ--)
    newCONSTSUB (stash, (char *)civ[-1].name, newSViv (civ[-1].iv));
}

SV *
ber_decode (SV *ber)
	CODE:
{
	STRLEN len;

        buf = SvPVbyte (ber, len);
        cur = buf;
        end = buf + len;

        RETVAL = decode_ber ();
}
        OUTPUT: RETVAL

void
ber_is (SV *tuple, SV *klass = &PL_sv_undef, SV *tag = &PL_sv_undef, SV *constructed = &PL_sv_undef, SV *data = &PL_sv_undef)
	PPCODE:
{
	if (!SvOK (tuple))
          XSRETURN_NO;

        if (!SvROK (tuple) || SvTYPE (SvRV (tuple)) != SVt_PVAV)
          croak ("ber_is: tuple must be BER tuple (array-ref)");

        AV *av = (AV *)SvRV (tuple);

        XPUSHs (
             (!SvOK (klass)       || SvIV  (AvARRAY (av)[BER_CLASS      ]) == SvIV (klass))
          && (!SvOK (tag)         || SvIV  (AvARRAY (av)[BER_TAG        ]) == SvIV (tag))
          && (!SvOK (constructed) || !SvIV (AvARRAY (av)[BER_CONSTRUCTED]) == !SvIV (constructed))
          && (!SvOK (data)        || sv_eq (AvARRAY (av)[BER_DATA       ], data))
          ? &PL_sv_yes : &PL_sv_undef);
}

void
ber_is_seq (SV *tuple)
	PPCODE:
{
	if (!SvOK (tuple))
          XSRETURN_UNDEF;

        AV *av = ber_tuple (tuple);

        XPUSHs (
             SvIV (AvARRAY (av)[BER_CLASS      ]) == ASN_UNIVERSAL
          && SvIV (AvARRAY (av)[BER_TAG        ]) == ASN_SEQUENCE
          && SvIV (AvARRAY (av)[BER_CONSTRUCTED])
          ? AvARRAY (av)[BER_DATA] : &PL_sv_undef);
}

void
ber_is_i32 (SV *tuple, SV *value = &PL_sv_undef)
	PPCODE:
{
	if (!SvOK (tuple))
          XSRETURN_NO;

        AV *av = ber_tuple (tuple);

        IV data = SvIV (AvARRAY (av)[BER_DATA]);

        XPUSHs (
               SvIV (AvARRAY (av)[BER_CLASS      ]) == ASN_UNIVERSAL
          &&   SvIV (AvARRAY (av)[BER_TAG        ]) == ASN_INTEGER32
          &&  !SvIV (AvARRAY (av)[BER_CONSTRUCTED])
          &&  (!SvOK (value) || data == SvIV (value))
          ? sv_2mortal (data ? newSViv (data) : newSVpv ("0 but true", 0))
          : &PL_sv_undef);
}

void
ber_is_oid (SV *tuple, SV *oid = &PL_sv_undef)
	PPCODE:
{
	if (!SvOK (tuple))
          XSRETURN_NO;

        AV *av = ber_tuple (tuple);

        XPUSHs (
              SvIV (AvARRAY (av)[BER_CLASS      ]) == ASN_UNIVERSAL
          &&  SvIV (AvARRAY (av)[BER_TAG        ]) == ASN_OBJECT_IDENTIFIER
          && !SvIV (AvARRAY (av)[BER_CONSTRUCTED])
          && (!SvOK (oid) || sv_eq (AvARRAY (av)[BER_DATA], oid))
          ? newSVsv (AvARRAY (av)[BER_DATA]) : &PL_sv_undef);
}

#############################################################################

void
ber_encode (SV *tuple)
	PPCODE:
{
	buf_sv = sv_2mortal (NEWSV (0, 256));
        SvPOK_only (buf_sv);
        set_buf (buf_sv);

        encode_ber (tuple);

        SvCUR_set (buf_sv, cur - buf);
        XPUSHs (buf_sv);
}

SV *
ber_i32 (IV iv)
	CODE:
{
	AV *av = newAV ();
        av_fill (av, BER_ARRAYSIZE - 1);
        AvARRAY (av)[BER_CLASS      ] = newSVcacheint (ASN_UNIVERSAL);
        AvARRAY (av)[BER_TAG        ] = newSVcacheint (ASN_INTEGER32);
        AvARRAY (av)[BER_CONSTRUCTED] = newSVcacheint (0);
        AvARRAY (av)[BER_DATA       ] = newSViv (iv);
        RETVAL = newRV_noinc ((SV *)av);
}
	OUTPUT: RETVAL

# TODO: not arrayref, but elements?
SV *
ber_seq (SV *arrayref)
	CODE:
{
	AV *av = newAV ();
        av_fill (av, BER_ARRAYSIZE - 1);
        AvARRAY (av)[BER_CLASS      ] = newSVcacheint (ASN_UNIVERSAL);
        AvARRAY (av)[BER_TAG        ] = newSVcacheint (ASN_SEQUENCE);
        AvARRAY (av)[BER_CONSTRUCTED] = newSVcacheint (1);
        AvARRAY (av)[BER_DATA       ] = newSVsv (arrayref);
        RETVAL = newRV_noinc ((SV *)av);
}
	OUTPUT: RETVAL