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Pl_ASCII85Decoder.cc

#include <qpdf/Pl_ASCII85Decoder.hh>
#include <qpdf/QEXC.hh>
#include <qpdf/QTC.hh>
#include <string.h>

Pl_ASCII85Decoder::Pl_ASCII85Decoder(char const* identifier, Pipeline* next) :
    Pipeline(identifier, next),
    pos(0),
    eod(0)
{
    memset(this->inbuf, 117, 5);
}

Pl_ASCII85Decoder::~Pl_ASCII85Decoder()
{
}

void
Pl_ASCII85Decoder::write(unsigned char* buf, int len)
{
    if (eod > 1)
    {
      return;
    }
    for (int i = 0; i < len; ++i)
    {
      if (eod > 1)
      {
          break;
      }
      else if (eod == 1)
      {
          if (buf[i] == '>')
          {
            flush();
            eod = 2;
          }
          else
          {
            throw QEXC::General(
                "broken end-of-data sequence in base 85 data");
          }
      }
      else
      {
          switch (buf[i])
          {
            case ' ':
            case '\f':
            case '\v':
            case '\t':
            case '\r':
            case '\n':
            QTC::TC("libtests", "Pl_ASCII85Decoder ignore space");
            // ignore whitespace
            break;

            case '~':
            eod = 1;
            break;

            case 'z':
            if (pos != 0)
            {
                throw QEXC::General(
                  "unexpected z during base 85 decode");
            }
            else
            {
                QTC::TC("libtests", "Pl_ASCII85Decoder read z");
                getNext()->write((unsigned char*)"\000\000\000\000", 4);
            }
            break;

            default:
            if ((buf[i] < 33) || (buf[i] > 117))
            {
                throw QEXC::General
                  ("character out of range during base 85 decode");
            }
            else
            {
                this->inbuf[this->pos++] = buf[i];
                if (pos == 5)
                {
                  flush();
                }
            }
            break;
          }
      }
    }
}

void
Pl_ASCII85Decoder::flush()
{
    if (this->pos == 0)
    {
      QTC::TC("libtests", "Pl_ASCII85Decoder no-op flush");
      return;
    }
    unsigned long lval = 0;
    for (int i = 0; i < 5; ++i)
    {
      lval *= 85;
      lval += (this->inbuf[i] - 33);
    }

    unsigned char outbuf[4];
    memset(outbuf, 0, 4);
    for (int i = 3; i >= 0; --i)
    {
      outbuf[i] = lval & 0xff;
      lval >>= 8;
    }

    QTC::TC("libtests", "Pl_ASCII85Decoder partial flush",
          (this->pos == 5) ? 0 : 1);
    getNext()->write(outbuf, this->pos - 1);

    this->pos = 0;
    memset(this->inbuf, 117, 5);
}

void
Pl_ASCII85Decoder::finish()
{
    flush();
    getNext()->finish();
}

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