Pl_TIFFPredictor.cc
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#include <qpdf/Pl_TIFFPredictor.hh>
#include <qpdf/BitStream.hh>
#include <qpdf/BitWriter.hh>
#include <qpdf/QTC.hh>
#include <qpdf/QUtil.hh>
#include <climits>
#include <stdexcept>
#include <cstring>
#include <vector>
Pl_TIFFPredictor::Pl_TIFFPredictor(
char const* identifier,
Pipeline* next,
action_e action,
unsigned int columns,
unsigned int samples_per_pixel,
unsigned int bits_per_sample) :
Pipeline(identifier, next),
action(action),
columns(columns),
samples_per_pixel(samples_per_pixel),
bits_per_sample(bits_per_sample),
pos(0)
{
if (samples_per_pixel < 1) {
throw std::runtime_error(
"TIFFPredictor created with invalid samples_per_pixel");
}
if ((bits_per_sample < 1) ||
(bits_per_sample > (8 * (sizeof(unsigned long long))))) {
throw std::runtime_error(
"TIFFPredictor created with invalid bits_per_sample");
}
unsigned long long bpr =
((columns * bits_per_sample * samples_per_pixel) + 7) / 8;
if ((bpr == 0) || (bpr > (UINT_MAX - 1))) {
throw std::runtime_error(
"TIFFPredictor created with invalid columns value");
}
this->bytes_per_row = bpr & UINT_MAX;
this->cur_row =
QUtil::make_shared_array<unsigned char>(this->bytes_per_row);
memset(this->cur_row.get(), 0, this->bytes_per_row);
}
void
Pl_TIFFPredictor::write(unsigned char const* data, size_t len)
{
size_t left = this->bytes_per_row - this->pos;
size_t offset = 0;
while (len >= left) {
// finish off current row
memcpy(this->cur_row.get() + this->pos, data + offset, left);
offset += left;
len -= left;
processRow();
// Prepare for next row
memset(this->cur_row.get(), 0, this->bytes_per_row);
left = this->bytes_per_row;
this->pos = 0;
}
if (len) {
memcpy(this->cur_row.get() + this->pos, data + offset, len);
}
this->pos += len;
}
void
Pl_TIFFPredictor::processRow()
{
QTC::TC(
"libtests",
"Pl_TIFFPredictor processRow",
(action == a_decode ? 0 : 1));
BitWriter bw(this->getNext());
BitStream in(this->cur_row.get(), this->bytes_per_row);
std::vector<long long> prev;
for (unsigned int i = 0; i < this->samples_per_pixel; ++i) {
long long sample = in.getBitsSigned(this->bits_per_sample);
bw.writeBitsSigned(sample, this->bits_per_sample);
prev.push_back(sample);
}
for (unsigned int col = 1; col < this->columns; ++col) {
for (unsigned int i = 0; i < this->samples_per_pixel; ++i) {
long long sample = in.getBitsSigned(this->bits_per_sample);
long long new_sample = sample;
if (action == a_encode) {
new_sample -= prev[i];
prev[i] = sample;
} else {
new_sample += prev[i];
prev[i] = new_sample;
}
bw.writeBitsSigned(new_sample, this->bits_per_sample);
}
}
bw.flush();
}
void
Pl_TIFFPredictor::finish()
{
if (this->pos) {
// write partial row
processRow();
}
this->pos = 0;
memset(this->cur_row.get(), 0, this->bytes_per_row);
getNext()->finish();
}