Hash dynamic keymap at runtime

quantum/dynamic_keymap.c

@@ -19,6 +19,7 @@
 #include "progmem.h" // to read default from flash
 #include "quantum.h" // for send_string()
 #include "dynamic_keymap.h"
+#include "fnv.h"
 
 #ifdef VIA_ENABLE
 #    include "via.h" // for VIA_EEPROM_CONFIG_END
@@ -147,6 +148,47 @@ void dynamic_keymap_set_encoder(uint8_t layer, uint8_t encoder_id, bool clockwis
 }
 #endif // ENCODER_MAP_ENABLE
 
+static uint32_t dynamic_keymap_compute_hash(void) {
+    Fnv32_t hash = FNV1_32A_INIT;
+
+    uint16_t keycode;
+    for (int layer = 0; layer < DYNAMIC_KEYMAP_LAYER_COUNT; layer++) {
+        for (int row = 0; row < MATRIX_ROWS; row++) {
+            for (int column = 0; column < MATRIX_COLS; column++) {
+                keycode = pgm_read_word(&keymaps[layer][row][column]);
+                hash    = fnv_32a_buf(&keycode, sizeof(keycode), hash);
+            }
+        }
+#ifdef ENCODER_MAP_ENABLE
+        for (int encoder = 0; encoder < NUM_ENCODERS; encoder++) {
+            keycode = pgm_read_word(&encoder_map[layer][encoder][0]);
+            hash    = fnv_32a_buf(&keycode, sizeof(keycode), hash);
+
+            keycode = pgm_read_word(&encoder_map[layer][encoder][1]);
+            hash    = fnv_32a_buf(&keycode, sizeof(keycode), hash);
+        }
+#endif // ENCODER_MAP_ENABLE
+    }
+
+    return hash;
+}
+
+static uint32_t dynamic_keymap_hash(void) {
+    static uint32_t hash = 0;
+
+    static uint8_t s_init = 0;
+    if (!s_init) {
+        s_init = 1;
+
+        hash = dynamic_keymap_compute_hash();
+    }
+    return hash;
+}
+
+bool dynamic_keymap_is_valid(void) {
+    return eeprom_read_dword(EECONFIG_KEYMAP_HASH) == dynamic_keymap_hash();
+}
+
 void dynamic_keymap_reset(void) {
     // Reset the keymaps in EEPROM to what is in flash.
     // All keyboards using dynamic keymaps should define a layout
@@ -164,6 +206,7 @@ void dynamic_keymap_reset(void) {
         }
 #endif // ENCODER_MAP_ENABLE
     }
+    eeprom_update_dword(EECONFIG_KEYMAP_HASH, dynamic_keymap_hash());
 }
 
 void dynamic_keymap_get_buffer(uint16_t offset, uint16_t size, uint8_t *data) {