From 53971d50be39448c980d842a1fe1f525b4cee597 Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Sat, 13 Jan 2018 14:15:20 -0500
Subject: Add Pl_TIFFPredictor

---
 libqpdf/Pl_TIFFPredictor.cc      | 123 +++++++++++++++++++++++++++++++++++++++
 libqpdf/build.mk                 |   1 +
 libqpdf/qpdf/Pl_TIFFPredictor.hh |  39 +++++++++++++
 3 files changed, 163 insertions(+)
 create mode 100644 libqpdf/Pl_TIFFPredictor.cc
 create mode 100644 libqpdf/qpdf/Pl_TIFFPredictor.hh

(limited to 'libqpdf')

diff --git a/libqpdf/Pl_TIFFPredictor.cc b/libqpdf/Pl_TIFFPredictor.cc
new file mode 100644
index 00000000..42cfbb1a
--- /dev/null
+++ b/libqpdf/Pl_TIFFPredictor.cc
@@ -0,0 +1,123 @@
+#include <qpdf/Pl_TIFFPredictor.hh>
+#include <qpdf/QTC.hh>
+#include <qpdf/BitStream.hh>
+#include <qpdf/BitWriter.hh>
+#include <stdexcept>
+#include <vector>
+#include <string.h>
+#include <limits.h>
+
+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),
+    cur_row(0),
+    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 = new unsigned char[this->bytes_per_row];
+    memset(this->cur_row, 0, this->bytes_per_row);
+}
+
+Pl_TIFFPredictor::~Pl_TIFFPredictor()
+{
+    delete [] cur_row;
+}
+
+void
+Pl_TIFFPredictor::write(unsigned char* 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 + this->pos, data + offset, left);
+	offset += left;
+	len -= left;
+
+	processRow();
+
+	// Prepare for next row
+	memset(this->cur_row, 0, this->bytes_per_row);
+	left = this->bytes_per_row;
+	this->pos = 0;
+    }
+    if (len)
+    {
+	memcpy(this->cur_row + 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, 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, 0, this->bytes_per_row);
+    getNext()->finish();
+}
diff --git a/libqpdf/build.mk b/libqpdf/build.mk
index 75d0054e..c75c3dd9 100644
--- a/libqpdf/build.mk
+++ b/libqpdf/build.mk
@@ -32,6 +32,7 @@ SRCS_libqpdf = \
 	libqpdf/Pl_RunLength.cc \
 	libqpdf/Pl_SHA2.cc \
 	libqpdf/Pl_StdioFile.cc \
+	libqpdf/Pl_TIFFPredictor.cc \
 	libqpdf/QPDF.cc \
 	libqpdf/QPDFExc.cc \
 	libqpdf/QPDFObjGen.cc \
diff --git a/libqpdf/qpdf/Pl_TIFFPredictor.hh b/libqpdf/qpdf/Pl_TIFFPredictor.hh
new file mode 100644
index 00000000..235068ee
--- /dev/null
+++ b/libqpdf/qpdf/Pl_TIFFPredictor.hh
@@ -0,0 +1,39 @@
+#ifndef __PL_TIFFPREDICTOR_HH__
+#define __PL_TIFFPREDICTOR_HH__
+
+// This pipeline reverses the application of a TIFF predictor as
+// described in the TIFF specification.
+
+#include <qpdf/Pipeline.hh>
+
+class Pl_TIFFPredictor: public Pipeline
+{
+  public:
+    enum action_e { a_encode, a_decode };
+
+    QPDF_DLL
+    Pl_TIFFPredictor(char const* identifier, Pipeline* next,
+                     action_e action, unsigned int columns,
+                     unsigned int samples_per_pixel = 1,
+                     unsigned int bits_per_sample = 8);
+    QPDF_DLL
+    virtual ~Pl_TIFFPredictor();
+
+    QPDF_DLL
+    virtual void write(unsigned char* data, size_t len);
+    QPDF_DLL
+    virtual void finish();
+
+  private:
+    void processRow();
+
+    action_e action;
+    unsigned int columns;
+    unsigned int bytes_per_row;
+    unsigned int samples_per_pixel;
+    unsigned int bits_per_sample;
+    unsigned char* cur_row;
+    size_t pos;
+};
+
+#endif // __PL_TIFFPREDICTOR_HH__
-- 
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