Add GamePadShift for handling shift-register-based buttons

3 files changed, 56 insertions, 10 deletions

diff --git a/shared-module/gamepad/GamePad.c b/shared-module/gamepad/GamePad.c
index 2c14fa02a..ed574db53 100644
--- a/shared-module/gamepad/GamePad.c
+++ b/shared-module/gamepad/GamePad.c
@@ -35,7 +35,7 @@
 #include "shared-bindings/util.h"
 
 
-void gamepad_init(size_t n_pins, const mp_obj_t* pins) {
+void gamepad_init_pins(size_t n_pins, const mp_obj_t* pins) {
     gamepad_obj_t* gamepad_singleton = MP_STATE_VM(gamepad_singleton);
     for (size_t i = 0; i < 8; ++i) {
         gamepad_singleton->pins[i] = NULL;
@@ -57,4 +57,23 @@ void gamepad_init(size_t n_pins, const mp_obj_t* pins) {
         gamepad_singleton->pins[i] = pin;
     }
     gamepad_singleton->last = 0;
+    gamepad_singleton->kind = GAMEPAD_KIND_PINS;
+}
+
+void gamepad_init_shift(digitalio_digitalinout_obj_t *data_pin,
+                        digitalio_digitalinout_obj_t *clock_pin,
+                        digitalio_digitalinout_obj_t *latch_pin) {
+    gamepad_obj_t* gamepad_singleton = MP_STATE_VM(gamepad_singleton);
+
+    common_hal_digitalio_digitalinout_switch_to_input(data_pin, PULL_NONE);
+    gamepad_singleton->pins[0] = data_pin;
+
+    common_hal_digitalio_digitalinout_switch_to_output(clock_pin, 0, DRIVE_MODE_PUSH_PULL);
+    gamepad_singleton->pins[1] = clock_pin;
+
+    common_hal_digitalio_digitalinout_switch_to_output(clock_pin, 1, DRIVE_MODE_PUSH_PULL);
+    gamepad_singleton->pins[2] = latch_pin;
+
+    gamepad_singleton->last = 0;
+    gamepad_singleton->kind = GAMEPAD_KIND_PINS;
 }
diff --git a/shared-module/gamepad/GamePad.h b/shared-module/gamepad/GamePad.h
index 9fd5c9626..9bc5a711c 100644
--- a/shared-module/gamepad/GamePad.h
+++ b/shared-module/gamepad/GamePad.h
@@ -37,8 +37,15 @@ typedef struct {
     volatile uint8_t last;
     volatile uint8_t pressed;
     uint8_t pulls;
+    uint8_t kind;
 } gamepad_obj_t;
 
-void gamepad_init(size_t n_pins, const mp_obj_t* pins);
+#define GAMEPAD_KIND_PINS 0
+#define GAMEPAD_KIND_SHIFT 1
+
+void gamepad_init_pins(size_t n_pins, const mp_obj_t* pins);
+void gamepad_init_shift(digitalio_digitalinout_obj_t *data_pin,
+                        digitalio_digitalinout_obj_t *clock_pin,
+                        digitalio_digitalinout_obj_t *latch_pin);
 
 #endif  // MICROPY_INCLUDED_GAMEPAD_GAMEPAD_H
diff --git a/shared-module/gamepad/__init__.c b/shared-module/gamepad/__init__.c
index 8414ddfbe..c79ee30ba 100644
--- a/shared-module/gamepad/__init__.c
+++ b/shared-module/gamepad/__init__.c
@@ -40,17 +40,37 @@ void gamepad_tick(void) {
     }
     uint8_t gamepad_current = 0;
     uint8_t bit = 1;
-    for (int i = 0; i < 8; ++i) {
-        digitalio_digitalinout_obj_t* pin = gamepad_singleton->pins[i];
-        if (!pin) {
-            break;
+    switch (gamepad_singleton->kind) {
+    case GAMEPAD_KIND_PINS:
+        for (int i = 0; i < 8; ++i) {
+            digitalio_digitalinout_obj_t* pin = gamepad_singleton->pins[i];
+            if (!pin) {
+                break;
+            }
+            if (common_hal_digitalio_digitalinout_get_value(pin)) {
+                gamepad_current |= bit;
+            }
+            bit <<= 1;
         }
-        if (common_hal_digitalio_digitalinout_get_value(pin)) {
-            gamepad_current |= bit;
+        gamepad_current ^= gamepad_singleton->pulls;
+        break;
+    case GAMEPAD_KIND_SHIFT:
+        bit = 1;
+        digitalio_digitalinout_obj_t* data_pin = gamepad_singleton->pins[0];
+        digitalio_digitalinout_obj_t* clock_pin = gamepad_singleton->pins[1];
+        digitalio_digitalinout_obj_t* latch_pin = gamepad_singleton->pins[2];
+        common_hal_digitalio_digitalinout_set_value(latch_pin, 0);
+        for (int i = 0; i < 8; ++i) {
+            common_hal_digitalio_digitalinout_set_value(clock_pin, 1);
+            if (common_hal_digitalio_digitalinout_get_value(data_pin)) {
+                gamepad_current |= bit;
+            }
+            bit <<= 1;
+            common_hal_digitalio_digitalinout_set_value(clock_pin, 0);
         }
-        bit <<= 1;
+        common_hal_digitalio_digitalinout_set_value(latch_pin, 1);
+        break;
     }
-    gamepad_current ^= gamepad_singleton->pulls;
     gamepad_singleton->pressed |= gamepad_singleton->last & gamepad_current;
     gamepad_singleton->last = gamepad_current;
 }