mirror of
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147 lines
4.1 KiB
C++
147 lines
4.1 KiB
C++
#include <qpdf/Pl_RunLength.hh>
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#include <qpdf/QTC.hh>
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#include <qpdf/QUtil.hh>
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Pl_RunLength::Members::Members(action_e action) :
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action(action),
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state(st_top),
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length(0)
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{
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}
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Pl_RunLength::Pl_RunLength(char const* identifier, Pipeline* next, action_e action) :
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Pipeline(identifier, next),
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m(new Members(action))
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{
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}
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Pl_RunLength::~Pl_RunLength() // NOLINT (modernize-use-equals-default)
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{
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// Must be explicit and not inline -- see QPDF_DLL_CLASS in README-maintainer
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}
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void
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Pl_RunLength::write(unsigned char const* data, size_t len)
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{
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if (m->action == a_encode) {
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encode(data, len);
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} else {
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decode(data, len);
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}
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}
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void
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Pl_RunLength::encode(unsigned char const* data, size_t len)
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{
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for (size_t i = 0; i < len; ++i) {
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if ((m->state == st_top) != (m->length <= 1)) {
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throw std::logic_error("Pl_RunLength::encode: state/length inconsistency");
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}
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unsigned char ch = data[i];
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if ((m->length > 0) && ((m->state == st_copying) || (m->length < 128)) &&
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(ch == m->buf[m->length - 1])) {
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QTC::TC("libtests", "Pl_RunLength: switch to run", (m->length == 128) ? 0 : 1);
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if (m->state == st_copying) {
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--m->length;
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flush_encode();
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m->buf[0] = ch;
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m->length = 1;
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}
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m->state = st_run;
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m->buf[m->length] = ch;
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++m->length;
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} else {
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if ((m->length == 128) || (m->state == st_run)) {
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flush_encode();
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} else if (m->length > 0) {
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m->state = st_copying;
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}
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m->buf[m->length] = ch;
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++m->length;
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}
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}
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}
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void
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Pl_RunLength::decode(unsigned char const* data, size_t len)
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{
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for (size_t i = 0; i < len; ++i) {
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unsigned char ch = data[i];
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switch (m->state) {
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case st_top:
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if (ch < 128) {
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// length represents remaining number of bytes to copy
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m->length = 1U + ch;
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m->state = st_copying;
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} else if (ch > 128) {
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// length represents number of copies of next byte
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m->length = 257U - ch;
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m->state = st_run;
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} else // ch == 128
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{
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// EOD; stay in this state
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}
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break;
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case st_copying:
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this->getNext()->write(&ch, 1);
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if (--m->length == 0) {
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m->state = st_top;
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}
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break;
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case st_run:
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for (unsigned int j = 0; j < m->length; ++j) {
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this->getNext()->write(&ch, 1);
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}
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m->state = st_top;
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break;
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}
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}
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}
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void
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Pl_RunLength::flush_encode()
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{
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if (m->length == 128) {
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QTC::TC(
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"libtests",
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"Pl_RunLength flush full buffer",
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(m->state == st_copying ? 0
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: m->state == st_run ? 1
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: -1));
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}
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if (m->length == 0) {
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QTC::TC("libtests", "Pl_RunLength flush empty buffer");
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}
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if (m->state == st_run) {
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if ((m->length < 2) || (m->length > 128)) {
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throw std::logic_error("Pl_RunLength: invalid length in flush_encode for run");
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}
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auto ch = static_cast<unsigned char>(257 - m->length);
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this->getNext()->write(&ch, 1);
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this->getNext()->write(&m->buf[0], 1);
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} else if (m->length > 0) {
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auto ch = static_cast<unsigned char>(m->length - 1);
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this->getNext()->write(&ch, 1);
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this->getNext()->write(m->buf, m->length);
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}
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m->state = st_top;
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m->length = 0;
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}
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void
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Pl_RunLength::finish()
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{
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// When decoding, we might have read a length byte not followed by data, which means the stream
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// was terminated early, but we will just ignore this case since this is the only sensible thing
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// to do.
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if (m->action == a_encode) {
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flush_encode();
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unsigned char ch = 128;
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this->getNext()->write(&ch, 1);
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}
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this->getNext()->finish();
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}
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