gcode_D EEPROM size, cleanup

Fixes #19920

Co-Authored-By: Orel <37673727+0r31@users.noreply.github.com>

Marlin/src/gcode/gcode_d.cpp

@@ -54,9 +54,7 @@
           size_t total = persistentStore.capacity();
           int pos = 0;
           const uint8_t value = 0x0;
-          while(total--) {
-            persistentStore.write_data(pos, &value, 1);
-          }
+          while (total--) persistentStore.write_data(pos, &value, 1);
           persistentStore.access_finish();
         #else
           settings.reset();
@@ -70,7 +68,7 @@
         uint8_t *pointer = parser.hex_adr_val('A');
         uint16_t len = parser.ushortval('C', 1);
         uintptr_t addr = (uintptr_t)pointer;
-        NOMORE(addr, (size_t)(SRAM_SIZE - 1));
+        NOMORE(addr, size_t(SRAM_SIZE - 1));
         NOMORE(len, SRAM_SIZE - addr);
         if (parser.seenval('X')) {
           // Write the hex bytes after the X
@@ -91,11 +89,8 @@
           uint8_t *pointer = parser.hex_adr_val('A');
           uint16_t len = parser.ushortval('C', 1);
           uintptr_t addr = (uintptr_t)pointer;
-          #ifndef MARLIN_EEPROM_SIZE
-            #define MARLIN_EEPROM_SIZE size_t(E2END + 1)
-          #endif
-          NOMORE(addr, (size_t)(MARLIN_EEPROM_SIZE - 1));
-          NOMORE(len, MARLIN_EEPROM_SIZE - addr);
+          NOMORE(addr, size_t(persistentStore.capacity() - 1));
+          NOMORE(len, persistentStore.capacity() - addr);
           if (parser.seenval('X')) {
             uint16_t val = parser.hex_val('X');
             #if ENABLED(EEPROM_SETTINGS)
@@ -111,23 +106,18 @@
             #endif
           }
           else {
-            while (len--) {
             // Read bytes from EEPROM
             #if ENABLED(EEPROM_SETTINGS)
               persistentStore.access_start();
-                uint8_t val;
-                while(len--) {
               int pos = 0;
-                  if (!persistentStore.read_data(pos, (uint8_t *)&val, sizeof(val))) {
-                    print_hex_byte(val);
-                  }
-                }
+              uint8_t val;
+              while (len--) if (!persistentStore.read_data(pos, &val, 1)) print_hex_byte(val);
               SERIAL_EOL();
               persistentStore.access_finish();
             #else
               SERIAL_ECHOLNPGM("NO EEPROM");
+              len = 0;
             #endif
-            }
             SERIAL_EOL();
           }
         } break;
@@ -156,7 +146,7 @@
         uint8_t *pointer = parser.hex_adr_val('A');
         uint16_t len = parser.ushortval('C', 1);
         uintptr_t addr = (uintptr_t)pointer;
-        NOMORE(addr, (size_t)(FLASH_SIZE - 1));
+        NOMORE(addr, size_t(FLASH_SIZE - 1));
         NOMORE(len, FLASH_SIZE - addr);
         if (parser.seenval('X')) {
           // TODO: Write the hex bytes after the X