[Keymap] crkbd/keymaps/rs: add rs keymap to corne keyboard and adapt others (#5181)

Update all my keymaps to work with 40 keys. Refactor code using
Userspace.

keyboards/crkbd/keymaps/rs/oled.c

@@ -0,0 +1,104 @@
+#ifdef SSD1306OLED
+#include QMK_KEYBOARD_H
+#include "ssd1306.h"
+#ifdef PROTOCOL_LUFA
+#include "lufa.h"
+#include "split_util.h"
+#endif
+
+extern uint8_t is_master;
+
+// When add source files to SRC in rules.mk, you can use functions.
+const char *read_logo(void);
+const char *read_keylog(void);
+const char *read_keylogs(void);
+void set_keylog(uint16_t keycode, keyrecord_t *record);
+
+void matrix_scan_user(void) { iota_gfx_task(); }
+
+typedef struct {
+  uint8_t state;
+  char name[8];
+} LAYER_DISPLAY_NAME;
+
+#define LAYER_DISPLAY_MAX 5
+const LAYER_DISPLAY_NAME layer_display_name[LAYER_DISPLAY_MAX] = {
+  {0, "Base"},
+  {2, "Code"},
+  {4, "Fn"},
+  {6, "Fn+Code"},
+  {__UINT8_MAX__, "?"},
+};
+static uint8_t layer_name_idx;
+static char layer_status_buf[24] = "Layer: Base\n";
+
+#ifdef RGBLIGHT_ENABLE
+// Following line allows macro to read current RGB settings
+extern rgblight_config_t rgblight_config;
+void update_keymap_status(void) {
+  snprintf(layer_status_buf, sizeof(layer_status_buf) - 1, "Layer:%s RGB: %d\n",
+           layer_display_name[layer_name_idx].name, rgblight_config.mode);
+}
+#else
+void update_keymap_status(void) {
+  snprintf(layer_status_buf, sizeof(layer_status_buf) - 1, "Layer:%s\n",
+           layer_display_name[layer_name_idx].name);
+}
+#endif
+
+void matrix_init_user(void) {
+  iota_gfx_init(!has_usb()); // turns on the display
+  update_keymap_status();
+}
+
+// declared in users/rs/rs.c
+void rgb_mod_changed_keymap(void) {
+  update_keymap_status();
+}
+
+// declared in users/rs/rs.c
+void keylog_set_keymap(uint16_t keycode, keyrecord_t *record) {
+  set_keylog(keycode, record);
+}
+
+uint32_t layer_state_set_user(uint32_t state) {
+  for (layer_name_idx = 0; layer_name_idx < LAYER_DISPLAY_MAX; ++layer_name_idx) {
+    if (state == 0 && layer_display_name[layer_name_idx].state == default_layer_state) {
+      break;
+    } else if (state != 0 && layer_display_name[layer_name_idx].state == state) {
+      break;
+    }
+  }
+  update_keymap_status();
+  return state;
+}
+
+static inline void render_keymap_status(struct CharacterMatrix *matrix) {
+  matrix_write(matrix, layer_status_buf);
+}
+
+void matrix_render_user(struct CharacterMatrix *matrix) {
+  if (is_master) {
+    render_keymap_status(matrix);
+    matrix_write_ln(matrix, read_keylog());
+    matrix_write_ln(matrix, read_keylogs());
+  } else {
+    matrix_write(matrix, read_logo());
+  }
+}
+
+void matrix_update(struct CharacterMatrix *dest, const struct CharacterMatrix *source) {
+  if (memcmp(dest->display, source->display, sizeof(dest->display))) {
+    memcpy(dest->display, source->display, sizeof(dest->display));
+    dest->dirty = true;
+  }
+}
+
+void iota_gfx_task_user(void) {
+  struct CharacterMatrix matrix;
+  matrix_clear(&matrix);
+  matrix_render_user(&matrix);
+  matrix_update(&display, &matrix);
+}
+
+#endif