loop_sdcard: Add loopable SD card file sections

To support continuous belt printing, add nestable repeat
loop support via an `[sdcard_loop]` module.

Supported G-Code:
  - SDCARD_LOOP_BEGIN COUNT=n  ; Loop for N times, or infinitely if N is 0
  - SDCARD_LOOP_END            ; End of loop
  - SDCARD_LOOP_DESIST         ; Complete all loops without iterating

Marlin M808 compatibility example in `config/sample-macros.cfg`:
  - M808 Ln        ; Loop for N times, or infinitely if N is 0
  - M808           ; End of loop
  - M808 K         ; Complete all loops without iterating

Added unit tests in test/klippy/sdcard_loop.test

See https://reprap.org/wiki/G-code#M808:_Set_or_Goto_Repeat_Marker

Signed-off-by: Jason S. McMullan <jason.mcmullan@gmail.com>

1 files changed, 23 insertions, 3 deletions

diff --git a/klippy/extras/virtual_sdcard.py b/klippy/extras/virtual_sdcard.py
index ccce3afe..66fc5ade 100644
--- a/klippy/extras/virtual_sdcard.py
+++ b/klippy/extras/virtual_sdcard.py
@@ -21,6 +21,7 @@ class VirtualSD:
         # Work timer
         self.reactor = printer.get_reactor()
         self.must_pause_work = self.cmd_from_sd = False
+        self.next_file_position = 0
         self.work_timer = None
         # Register commands
         self.gcode = printer.lookup_object('gcode')
@@ -124,7 +125,7 @@ class VirtualSD:
         if filename[0] == '/':
             filename = filename[1:]
         self._load_file(gcmd, filename, check_subdirs=True)
-        self.cmd_M24(gcmd)
+        self.do_resume()
     def cmd_M20(self, gcmd):
         # List SD card
         files = self.get_file_list()
@@ -191,6 +192,12 @@ class VirtualSD:
             return
         gcmd.respond_raw("SD printing byte %d/%d"
                          % (self.file_position, self.file_size))
+    def get_file_position(self):
+        return self.next_file_position
+    def set_file_position(self, pos):
+        self.next_file_position = pos
+    def is_cmd_from_sd(self):
+        return self.cmd_from_sd
     # Background work timer
     def work_handler(self, eventtime):
         logging.info("Starting SD card print (position %d)", self.file_position)
@@ -232,8 +239,11 @@ class VirtualSD:
                 continue
             # Dispatch command
             self.cmd_from_sd = True
+            line = lines.pop()
+            next_file_position = self.file_position + len(line) + 1
+            self.next_file_position = next_file_position
             try:
-                self.gcode.run_script(lines[-1])
+                self.gcode.run_script(line)
             except self.gcode.error as e:
                 self.print_stats.note_error(str(e))
                 break
@@ -241,7 +251,17 @@ class VirtualSD:
                 logging.exception("virtual_sdcard dispatch")
                 break
             self.cmd_from_sd = False
-            self.file_position += len(lines.pop()) + 1
+            self.file_position = self.next_file_position
+            # Do we need to skip around?
+            if self.next_file_position != next_file_position:
+                try:
+                    self.current_file.seek(self.file_position)
+                except:
+                    logging.exception("virtual_sdcard seek")
+                    self.work_timer = None
+                    return self.reactor.NEVER
+                lines = []
+                partial_input = ""
         logging.info("Exiting SD card print (position %d)", self.file_position)
         self.work_timer = None
         self.cmd_from_sd = False