brdecode, a tool to decompress print files

.gitignore

@@ -16,5 +16,6 @@
 # Binaries
 #
 /rastertobrlaser
+/brdecode
 /brlaser.drv
 *.o

Makefile.am

@@ -6,6 +6,9 @@ filterdir = $(CUPS_SERVERBIN)/filter
 drv_DATA = brlaser.drv
 drvdir = $(CUPS_DATADIR)/drv
 
+noinst_PROGRAMS = brdecode
+
+
 rastertobrlaser_SOURCES = \
 	src/main.cc \
 	src/debug.h \
@@ -16,3 +19,6 @@ rastertobrlaser_SOURCES = \
 	src/line.cc
 rastertobrlaser_CPPFLAGS = $(CUPS_CFLAGS)
 rastertobrlaser_LDADD = $(CUPS_LIBS)
+
+brdecode_SOURCES = \
+	src/brdecode.cc

src/brdecode.cc

@@ -0,0 +1,207 @@
+// A quick-and-dirty tool to convert print files back to pbm images.
+//
+// Copyright 2013 Peter De Wachter
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#include <stdint.h>
+#include <unistd.h>
+#include <algorithm>
+#include <exception>
+#include <vector>
+
+#define LINE_SIZE 1200
+
+namespace {
+
+FILE * in_file;
+std::vector<uint8_t> page;
+uint8_t line[LINE_SIZE] = { 0 };
+size_t line_offset;
+size_t num_lines = 0;
+
+
+class unexpected_eof: public std::exception {
+ public:
+  virtual const char *what() const noexcept {
+    return "Unexpected EOF";
+  }
+};
+
+class line_overflow: public std::exception {
+ public:
+  virtual const char *what() const noexcept {
+    return "Line buffer overflow, recompile with bigger LINE_SIZE";
+  }
+};
+
+
+uint8_t get() {
+  int ch = getc(in_file);
+  if (ch < 0)
+    throw unexpected_eof();
+  return ch;
+}
+
+unsigned read_overflow() {
+  uint8_t ch;
+  unsigned sum = 0;
+  do {
+    ch = get();
+    sum += ch;
+  } while (ch == 255);
+  return sum;
+}
+
+void read_repeat(uint8_t cmd) {
+  uint16_t offset = (cmd >> 5) & 3;
+  if (offset == 3)
+    offset += read_overflow();
+  uint16_t count = cmd & 31;
+  if (count == 31)
+    count += read_overflow();
+  count += 2;
+  uint8_t data = get();
+
+  if (line_offset + offset + count > sizeof(line))
+    throw line_overflow();
+  line_offset += offset;
+  std::fill_n(line + line_offset, count, data);
+  line_offset += count;
+}
+
+void read_substitute(uint8_t cmd) {
+  uint16_t offset = (cmd >> 3) & 15;
+  if (offset == 15)
+    offset += read_overflow();
+  uint16_t count = cmd & 7;
+  if (count == 7)
+    count += read_overflow();
+  count += 1;
+
+  if (line_offset + offset + count > sizeof(line))
+    throw line_overflow();
+  line_offset += offset;
+  std::generate_n(line + line_offset, count, get);
+  line_offset += count;
+}
+
+void read_edit() {
+  int8_t cmd = get();
+  if (cmd < 0) {
+    read_repeat(cmd);
+  } else {
+    read_substitute(cmd);
+  }
+}
+
+void read_line() {
+  uint8_t num_edits = get();
+  if (num_edits == 255) {
+    std::fill_n(line, sizeof(line), 0);
+  } else {
+    line_offset = 0;
+    for (int i = 0; i < num_edits; ++i) {
+      read_edit();
+    }
+  }
+  page.insert(page.end(), line, line + sizeof(line));
+  ++num_lines;
+}
+
+void read_block() {
+  uint8_t count = get();
+  count = count * 256 + get();
+  for (int i = 0; i < count; ++i) {
+    read_line();
+  }
+}
+
+bool read_page() {
+  bool in_esc = true;
+  int ch;
+
+  page.clear();
+  page.reserve(20 * 1000 * 1000);
+  num_lines = 0;
+
+  while ((ch = getc(in_file)) >= 0) {
+    if (ch == '\f') {
+      in_esc = false;
+      break;
+    } else if (ch == 033) {
+      in_esc = true;
+    } else if (in_esc && ch == 'w') {
+      read_block();
+    } else if (in_esc && (ch >= 'A' && ch <= 'Z')) {
+      in_esc = false;
+    }
+  }
+  return !page.empty();
+}
+
+}  // namespace
+
+int main(int argc, char *argv[]) {
+  const char *in_filename;
+  std::string out_prefix;
+
+  if (argc > 2) {
+    in_filename = argv[1];
+    out_prefix = argv[2];
+  } else if (argc > 1) {
+    in_filename = argv[1];
+    out_prefix = argv[1];
+  } else {
+    in_filename = nullptr;
+    out_prefix = "page";
+  }
+
+  if (in_filename) {
+    in_file = fopen(in_filename, "rb");
+    if (!in_file) {
+      fprintf(stderr, "Can't open file \"%s\"\n", in_filename);
+      return 1;
+    }
+  } else {
+    in_file = stdin;
+    if (isatty(0)) {
+      fprintf(stderr, "No filename given and no input on stdin\n");
+      return 1;
+    }
+  }
+
+  try {
+    int page_num = 1;
+    while (read_page()) {
+      std::string out_filename = out_prefix
+        + "-" + std::to_string(page_num) + ".pbm";
+      FILE *out_file = fopen(out_filename.c_str(), "wb");
+      if (!out_file) {
+        fprintf(stderr, "Can't write file \"%s\"\n", out_filename.c_str());
+        return 1;
+      }
+      size_t width = sizeof(line) * 8;
+      fprintf(out_file, "P4 %zd %zd\n", width, num_lines);
+      fwrite(page.data(), 1, page.size(), out_file);
+      fclose(out_file);
+      fprintf(stderr, "%s\n", out_filename.c_str());
+      ++page_num;
+    }
+  } catch (std::exception &e) {
+    fprintf(stderr, "%s\n", e.what());
+    return 1;
+  }
+  return 0;
+}