按源同步单位切换当前位置

结论：依据 LinuxCNC interp_convert.cc convert_length_units 与 unit_tests/interp/test_interp_basics.cc，G20/G21 切换时事件桥同步重标定当前线性坐标，native/source-link 覆盖通过。

core/src/canon_event_sink.cpp

@@ -234,6 +234,41 @@ void CanonEventSink::set_xy_rotation(double angle_degrees, int line) {
 }
 
 void CanonEventSink::use_length_units(double scale, int line) {
+    use_length_units(scale, line, false);
+}
+
+void CanonEventSink::use_length_units(double scale, int line, bool rescale_linear_state) {
+    if (rescale_linear_state && unit_scale_ != 0.0 && scale != unit_scale_) {
+        const double factor = unit_scale_ / scale;
+        // LinuxCNC src/emc/rs274ngc/interp_convert.cc convert_length_units()
+        // rescales linear current axes on G20/G21; A/B/C remain angular.
+        position_.x *= factor;
+        position_.y *= factor;
+        position_.z *= factor;
+        position_.u *= factor;
+        position_.v *= factor;
+        position_.w *= factor;
+        tool_length_offset_.x *= factor;
+        tool_length_offset_.y *= factor;
+        tool_length_offset_.z *= factor;
+        tool_length_offset_.u *= factor;
+        tool_length_offset_.v *= factor;
+        tool_length_offset_.w *= factor;
+        probe_position_.x *= factor;
+        probe_position_.y *= factor;
+        probe_position_.z *= factor;
+        probe_position_.u *= factor;
+        probe_position_.v *= factor;
+        probe_position_.w *= factor;
+        if (has_pending_motion_start_) {
+            pending_motion_start_.x *= factor;
+            pending_motion_start_.y *= factor;
+            pending_motion_start_.z *= factor;
+            pending_motion_start_.u *= factor;
+            pending_motion_start_.v *= factor;
+            pending_motion_start_.w *= factor;
+        }
+    }
     unit_scale_ = scale;
     CncSimEvent event = base_event(CNC_SIM_EVENT_SET_UNITS, line);
     event.feed = scale;

core/src/canon_event_sink.h

@@ -29,6 +29,7 @@ public:
     void set_xy_rotation(double angle_degrees, int line);
 
     void use_length_units(double scale, int line);
+    void use_length_units(double scale, int line, bool rescale_linear_state);
     void select_plane(int plane, int line);
     void set_traverse_rate(double rate);
     void set_feed_rate(double feed, int line);

core/src/linuxcnc_canon_bridge.cpp

@@ -193,7 +193,7 @@ void INIT_CANON() {
 void USE_LENGTH_UNITS(CANON_UNITS units) {
     trace_call("USE_LENGTH_UNITS");
     if (active_sink) {
-        active_sink->use_length_units(units_to_scale(units), event_line());
+        active_sink->use_length_units(units_to_scale(units), event_line(), true);
     }
 }
 

test-linuxcnc-rs274-native.sh

@@ -1174,6 +1174,10 @@ CNC_SIM_RS274_VAR="$var_file" "$build_dir/linuxcnc_rs274_dump" tests/gcode/linux
 # src/emc/rs274ngc/interp_read.cc returns INTERP_ENDFILE at the matching '%',
 # so later lines are ignored.
 CNC_SIM_RS274_FILE_MODE=1 CNC_SIM_RS274_VAR="$var_file" "$build_dir/linuxcnc_rs274_dump" tests/gcode/linuxcnc_percent_file_ignores_trailing.ngc >"$output_dir/cnc_sim_linuxcnc_percent_file_ignores_trailing.json"
+# Source basis: LinuxCNC unit_tests/interp/test_interp_basics.cc Convert G20 / G21
+# asserts that unit changes rescale current linear axes and work/G92 linear
+# offsets while rotary axes remain angular values.
+CNC_SIM_RS274_VAR="$var_file" "$build_dir/linuxcnc_rs274_dump" tests/gcode/linuxcnc_units_current_position.ngc >"$output_dir/cnc_sim_linuxcnc_units_current_position.json"
 CNC_SIM_RS274_NATIVE_OUTPUT_DIR="$output_dir" python3 - <<'PY'
 import json
 import os
@@ -1199,6 +1203,27 @@ required_motion = {"set-units", "set-plane", "set-spindle", "rapid", "set-feed",
 check(OUTPUT_DIR / "cnc_sim_linuxcnc_basic_motion.json", required_motion)
 check(OUTPUT_DIR / "cnc_sim_linuxcnc_basic_mill.json", required_motion | {"tool-change"})
 
+units_current_position = load("cnc_sim_linuxcnc_units_current_position.json")
+units_rapid = [
+    event
+    for event in units_current_position
+    if event["type"] == "rapid"
+]
+if len(units_rapid) != 3:
+    raise SystemExit(f"unexpected unit-current-position rapid count: {len(units_rapid)}")
+if units_rapid[1]["start"] != units_rapid[1]["end"]:
+    raise SystemExit(
+        "LinuxCNC G21 current-position rescale was not reflected before the metric no-op rapid: "
+        f"{units_rapid[1]!r}"
+    )
+if units_rapid[2]["start"] != units_rapid[2]["end"]:
+    raise SystemExit(
+        "LinuxCNC G20 current-position rescale was not reflected before the inch no-op rapid: "
+        f"{units_rapid[2]!r}"
+    )
+if (units_rapid[1]["end"]["a"], units_rapid[1]["end"]["b"], units_rapid[1]["end"]["c"]) != (4, 5, 6):
+    raise SystemExit("LinuxCNC G21 unit change unexpectedly scaled rotary axes")
+
 fractional_linenumbers = load("cnc_sim_linuxcnc_fractional_linenumbers.json")
 fractional_spindle_states = [
     (event["line"], event["spindle"])
@@ -3050,6 +3075,7 @@ echo "dumped $output_dir/cnc_sim_linuxcnc_arc_distance_modes.json"
 echo "dumped $output_dir/cnc_sim_linuxcnc_arc_center_tolerance_good_imperial.json"
 echo "dumped $output_dir/cnc_sim_linuxcnc_arc_center_tolerance_tight_metric_default.json"
 echo "dumped $output_dir/cnc_sim_linuxcnc_arc_center_tolerance_tight_metric_ini.err"
+echo "dumped $output_dir/cnc_sim_linuxcnc_units_current_position.json"
 echo "dumped $output_dir/cnc_sim_linuxcnc_predefined_positions.json"
 echo "dumped $output_dir/cnc_sim_linuxcnc_machine_coordinates.json"
 echo "dumped $output_dir/cnc_sim_linuxcnc_cutter_comp.json"

test-linuxcnc-source-link.sh

@@ -1858,6 +1858,12 @@ CNC_SIM_RS274_VAR="$var_file" \
 CNC_SIM_RS274_FILE_MODE=1 CNC_SIM_RS274_VAR="$var_file" \
     "$build_dir/linuxcnc_rs274_source_dump" tests/gcode/linuxcnc_percent_file_ignores_trailing.ngc \
     >"$output_dir/cnc_sim_linuxcnc_source_percent_file_ignores_trailing.json"
+# Source basis: LinuxCNC unit_tests/interp/test_interp_basics.cc Convert G20 / G21
+# asserts that unit changes rescale current linear axes while rotary axes remain
+# angular values.
+CNC_SIM_RS274_VAR="$var_file" \
+    "$build_dir/linuxcnc_rs274_source_dump" tests/gcode/linuxcnc_units_current_position.ngc \
+    >"$output_dir/cnc_sim_linuxcnc_source_units_current_position.json"
 
 CNC_SIM_RS274_SOURCE_OUTPUT_DIR="$output_dir" python3 - <<'PY'
 import json
@@ -1895,6 +1901,27 @@ required_motion = {
 check_motion("cnc_sim_linuxcnc_source_basic_motion.json", required_motion)
 check_motion("cnc_sim_linuxcnc_source_basic_mill.json", required_motion | {"tool-change"})
 
+units_current_position = load("cnc_sim_linuxcnc_source_units_current_position.json")
+units_rapid = [
+    event
+    for event in units_current_position
+    if event["type"] == "rapid"
+]
+if len(units_rapid) != 3:
+    raise SystemExit(f"unexpected source-linked unit-current-position rapid count: {len(units_rapid)}")
+if units_rapid[1]["start"] != units_rapid[1]["end"]:
+    raise SystemExit(
+        "source-linked LinuxCNC G21 current-position rescale was not reflected before the metric no-op rapid: "
+        f"{units_rapid[1]!r}"
+    )
+if units_rapid[2]["start"] != units_rapid[2]["end"]:
+    raise SystemExit(
+        "source-linked LinuxCNC G20 current-position rescale was not reflected before the inch no-op rapid: "
+        f"{units_rapid[2]!r}"
+    )
+if (units_rapid[1]["end"]["a"], units_rapid[1]["end"]["b"], units_rapid[1]["end"]["c"]) != (4, 5, 6):
+    raise SystemExit("source-linked LinuxCNC G21 unit change unexpectedly scaled rotary axes")
+
 fractional_linenumbers = load("cnc_sim_linuxcnc_source_fractional_linenumbers.json")
 fractional_spindle_states = [
     (event["line"], event["spindle"])
@@ -4148,3 +4175,4 @@ echo "dumped $output_dir/cnc_sim_linuxcnc_source_fractional_linenumbers.json"
 echo "dumped $output_dir/cnc_sim_linuxcnc_source_extended_linenumbers.json"
 echo "dumped $output_dir/cnc_sim_linuxcnc_source_close_and_downcase_words.json"
 echo "dumped $output_dir/cnc_sim_linuxcnc_source_percent_file_ignores_trailing.json"
+echo "dumped $output_dir/cnc_sim_linuxcnc_source_units_current_position.json"

tests/gcode/linuxcnc_units_current_position.ngc

@@ -0,0 +1,8 @@
+G20 G90 G17
+(Source basis: LinuxCNC unit_tests/interp/test_interp_basics.cc Convert G20 / G21 verifies that current linear axes rescale on unit changes while rotary axes keep angular values.)
+G0 X1 Y2 Z3 A4 B5 C6
+G21
+G0 X25.4 Y50.8 Z76.2 A4 B5 C6
+G20
+G0 X1 Y2 Z3 A4 B5 C6
+M30