1 files changed, 90 insertions, 0 deletions
diff --git a/circuitpython/shared-module/rotaryio/IncrementalEncoder.c b/circuitpython/shared-module/rotaryio/IncrementalEncoder.c
new file mode 100644
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+++ b/circuitpython/shared-module/rotaryio/IncrementalEncoder.c
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+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Jeff Epler for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#if CIRCUITPY_ROTARYIO && CIRCUITPY_ROTARYIO_SOFTENCODER
+#include "shared-bindings/rotaryio/IncrementalEncoder.h"
+#include "shared-module/rotaryio/IncrementalEncoder.h"
+#include "common-hal/rotaryio/IncrementalEncoder.h"
+
+void shared_module_softencoder_state_init(rotaryio_incrementalencoder_obj_t *self, uint8_t quiescent_state) {
+    self->state = quiescent_state;
+    self->sub_count = 0;
+    common_hal_rotaryio_incrementalencoder_set_position(self, 0);
+}
+
+void shared_module_softencoder_state_update(rotaryio_incrementalencoder_obj_t *self, uint8_t new_state) {
+    static const int8_t transitions[16] = {
+        0,    // 00 -> 00 no movement
+        -1,   // 00 -> 01 3/4 ccw (11 detent) or 1/4 ccw (00 at detent)
+        +1,   // 00 -> 10 3/4 cw or 1/4 cw
+        0,     // 00 -> 11 non-Gray-code transition
+        +1,   // 01 -> 00 2/4 or 4/4 cw
+        0,    // 01 -> 01 no movement
+        0,    // 01 -> 10 non-Gray-code transition
+        -1,   // 01 -> 11 4/4 or 2/4 ccw
+        -1,   // 10 -> 00 2/4 or 4/4 ccw
+        0,    // 10 -> 01 non-Gray-code transition
+        0,    // 10 -> 10 no movement
+        +1,   // 10 -> 11 4/4 or 2/4 cw
+        0,    // 11 -> 00 non-Gray-code transition
+        +1,   // 11 -> 01 1/4 or 3/4 cw
+        -1,   // 11 -> 10 1/4 or 3/4 ccw
+        0,    // 11 -> 11 no movement
+    };
+
+    new_state &= 0x3;
+    int idx = (self->state << 2) | new_state;
+    self->state = new_state;
+
+    int8_t sub_incr = transitions[idx];
+
+    self->sub_count += sub_incr;
+
+    if (self->sub_count >= self->divisor) {
+        self->position += 1;
+        self->sub_count = 0;
+    } else if (self->sub_count <= -self->divisor) {
+        self->position -= 1;
+        self->sub_count = 0;
+    }
+}
+
+mp_int_t common_hal_rotaryio_incrementalencoder_get_position(rotaryio_incrementalencoder_obj_t *self) {
+    return self->position;
+}
+
+void common_hal_rotaryio_incrementalencoder_set_position(rotaryio_incrementalencoder_obj_t *self, mp_int_t position) {
+    self->position = position;
+}
+
+mp_int_t common_hal_rotaryio_incrementalencoder_get_divisor(rotaryio_incrementalencoder_obj_t *self) {
+    return self->divisor;
+}
+
+void common_hal_rotaryio_incrementalencoder_set_divisor(rotaryio_incrementalencoder_obj_t *self, mp_int_t divisor) {
+    self->divisor = divisor;
+}
+#endif