From 9c5086e6af1e31095fc691090969e97e4828f72b Mon Sep 17 00:00:00 2001
From: Eric Ptak <trouch@trouch.com>
Date: Sun, 11 Aug 2019 02:14:31 +0200
Subject: [PATCH] [STM32F1] Simpler Flash EEPROM (#14829)

---
 .../HAL_STM32F1/persistent_store_flash.cpp    | 36 ++++++-------------
 Marlin/src/module/configuration_store.cpp     | 27 +++-----------
 Marlin/src/pins/stm32/pins_FYSETC_CHEETAH.h   |  6 ++++
 3 files changed, 21 insertions(+), 48 deletions(-)

diff --git a/Marlin/src/HAL/HAL_STM32F1/persistent_store_flash.cpp b/Marlin/src/HAL/HAL_STM32F1/persistent_store_flash.cpp
index 7004d88ffd..8097a28487 100644
--- a/Marlin/src/HAL/HAL_STM32F1/persistent_store_flash.cpp
+++ b/Marlin/src/HAL/HAL_STM32F1/persistent_store_flash.cpp
@@ -42,7 +42,6 @@
 // Store settings in the last two pages
 // Flash pages must be erased before writing, so keep track.
 bool firstWrite = false;
-uint32_t pageBase = EEPROM_START_ADDRESS;
 
 bool PersistentStore::access_start() {
   firstWrite = true;
@@ -67,42 +66,27 @@ bool PersistentStore::write_data(int &pos, const uint8_t *value, size_t size, ui
     firstWrite = false;
   }
 
-  // First write full words
-  int i = 0;
-  int wordsToWrite = size / sizeof(uint16_t);
-  uint16_t* wordBuffer = (uint16_t *)value;
-  while (wordsToWrite) {
-    status = FLASH_ProgramHalfWord(pageBase + pos + (i * 2), wordBuffer[i]);
-    if (status != FLASH_COMPLETE) return true;
-    wordsToWrite--;
-    i++;
-  }
-
-  // Now, write any remaining single byte
-  const uint16_t odd = size & 1;
-  if (odd) {
-    uint16_t temp = value[size - 1];
-    status = FLASH_ProgramHalfWord(pageBase + pos + i, temp);
-    if (status != FLASH_COMPLETE) return true;
+  for (size_t i = 0; i < size; i++) {
+    if (FLASH_ProgramHalfWord(EEPROM_PAGE0_BASE + (pos + i) * 2, value[i]) != FLASH_COMPLETE)
+      return true;
   }
 
   crc16(crc, value, size);
-  pos += size + odd;
+  pos += size;
   return false;
 }
 
 bool PersistentStore::read_data(int &pos, uint8_t* value, const size_t size, uint16_t *crc, const bool writing/*=true*/) {
-  for (uint16_t i = 0; i < size; i++) {
-    byte* accessPoint = (byte*)(pageBase + pos + i);
-    uint8_t c = *accessPoint;
-    if (writing) value[i] = c;
-    crc16(crc, &c, 1);
+  for (size_t i = 0; i < size; i++) {
+    uint8_t v = *(uint16_t *)(EEPROM_PAGE0_BASE + (pos + i) * 2);
+    if (writing) value[i] = v;
+    crc16(crc, &v, 1);
   }
-  pos += ((size + 1) & ~1); // i.e., size+(size&1), round up odd values
+  pos += size;
   return false;
 }
 
-size_t PersistentStore::capacity() { return E2END + 1; }
+size_t PersistentStore::capacity() { return size_t(E2END + 1); }
 
 #endif // EEPROM_SETTINGS && EEPROM FLASH
 #endif // __STM32F1__
diff --git a/Marlin/src/module/configuration_store.cpp b/Marlin/src/module/configuration_store.cpp
index da3a52035d..161e360c21 100644
--- a/Marlin/src/module/configuration_store.cpp
+++ b/Marlin/src/module/configuration_store.cpp
@@ -447,36 +447,19 @@ void MarlinSettings::postprocess() {
 
 #if ENABLED(EEPROM_SETTINGS)
 
-  #define WORD_PADDED_EEPROM ENABLED(__STM32F1__, FLASH_EEPROM_EMULATION)
-
-  #if WORD_PADDED_EEPROM && ENABLED(DEBUG_EEPROM_READWRITE)
-    #define UPDATE_TEST_INDEX(VAR) (test_index += sizeof(VAR))
-  #else
-    #define UPDATE_TEST_INDEX(VAR) NOOP
-  #endif
-  #if WORD_PADDED_EEPROM
-    #define EEPROM_SKIP(VAR) do{ eeprom_index += sizeof(VAR) + (sizeof(VAR) & 1); UPDATE_TEST_INDEX(sizeof(VAR)); }while(0)
-  #else
-    #define EEPROM_SKIP(VAR) (eeprom_index += sizeof(VAR))
-  #endif
-
   #define EEPROM_START()          if (!persistentStore.access_start()) { SERIAL_ECHO_MSG("No EEPROM."); return false; } \
                                   int eeprom_index = EEPROM_OFFSET
   #define EEPROM_FINISH()         persistentStore.access_finish()
-  #define EEPROM_WRITE(VAR)       do{ persistentStore.write_data(eeprom_index, (uint8_t*)&VAR, sizeof(VAR), &working_crc);              UPDATE_TEST_INDEX(VAR); }while(0)
-  #define EEPROM_READ(VAR)        do{ persistentStore.read_data(eeprom_index, (uint8_t*)&VAR, sizeof(VAR), &working_crc, !validating);  UPDATE_TEST_INDEX(VAR); }while(0)
-  #define EEPROM_READ_ALWAYS(VAR) do{ persistentStore.read_data(eeprom_index, (uint8_t*)&VAR, sizeof(VAR), &working_crc);               UPDATE_TEST_INDEX(VAR); }while(0)
+  #define EEPROM_SKIP(VAR)        (eeprom_index += sizeof(VAR))
+  #define EEPROM_WRITE(VAR)       do{ persistentStore.write_data(eeprom_index, (uint8_t*)&VAR, sizeof(VAR), &working_crc);              }while(0)
+  #define EEPROM_READ(VAR)        do{ persistentStore.read_data(eeprom_index, (uint8_t*)&VAR, sizeof(VAR), &working_crc, !validating);  }while(0)
+  #define EEPROM_READ_ALWAYS(VAR) do{ persistentStore.read_data(eeprom_index, (uint8_t*)&VAR, sizeof(VAR), &working_crc);               }while(0)
   #define EEPROM_ASSERT(TST,ERR)  do{ if (!(TST)) { SERIAL_ERROR_MSG(ERR); eeprom_error = true; } }while(0)
 
   #if ENABLED(DEBUG_EEPROM_READWRITE)
-    #if WORD_PADDED_EEPROM
-      int test_index;
-    #else
-      #define test_index eeprom_index
-    #endif
     #define _FIELD_TEST(FIELD) \
       EEPROM_ASSERT( \
-        eeprom_error || test_index == offsetof(SettingsData, FIELD) + EEPROM_OFFSET, \
+        eeprom_error || eeprom_index == offsetof(SettingsData, FIELD) + EEPROM_OFFSET, \
         "Field " STRINGIFY(FIELD) " mismatch." \
       )
   #else
diff --git a/Marlin/src/pins/stm32/pins_FYSETC_CHEETAH.h b/Marlin/src/pins/stm32/pins_FYSETC_CHEETAH.h
index e3aac9e84a..b40507f43c 100644
--- a/Marlin/src/pins/stm32/pins_FYSETC_CHEETAH.h
+++ b/Marlin/src/pins/stm32/pins_FYSETC_CHEETAH.h
@@ -35,6 +35,12 @@
 
 #define DISABLE_JTAG
 
+#define FLASH_EEPROM_EMULATION
+#define EEPROM_PAGE_SIZE     uint16(0x800) // 2KB
+#define EEPROM_START_ADDRESS uint32(0x8000000 + 256 * 1024 - 2 * EEPROM_PAGE_SIZE)
+#undef E2END
+#define E2END                (EEPROM_PAGE_SIZE - 1) // 2KB
+
 //
 // Servos
 //