⚡️ Fix MMU2 sscanf bug, optimize (#26449)

Co-authored-by: Scott Lahteine <thinkyhead@users.noreply.github.com>

Marlin/src/feature/mmu/mmu2.cpp

@@ -76,15 +76,14 @@ MMU2 mmu2;
 #define MMU2_NO_TOOL 99
 #define MMU_BAUD    115200
 
-bool MMU2::_enabled, MMU2::ready, MMU2::mmu_print_saved;
+bool MMU2::_enabled, MMU2::ready;
 #if HAS_PRUSA_MMU2S
   bool MMU2::mmu2s_triggered;
 #endif
 uint8_t MMU2::cmd, MMU2::cmd_arg, MMU2::last_cmd, MMU2::extruder;
 int8_t MMU2::state = 0;
 volatile int8_t MMU2::finda = 1;
 volatile bool MMU2::finda_runout_valid;
-uint16_t MMU2::version = 0, MMU2::buildnr = 0;
 millis_t MMU2::prev_request, MMU2::prev_P0_request;
 char MMU2::rx_buffer[MMU_RX_SIZE], MMU2::tx_buffer[MMU_TX_SIZE];
 
@@ -146,6 +145,7 @@ void mmu2_attn_buzz(const bool two=false) {
   if (two) { BUZZ(10, 0); BUZZ(200, 404); }
 }
 
+// Avoiding sscanf significantly reduces build size
 void MMU2::mmu_loop() {
 
   switch (state) {
@@ -168,7 +168,7 @@ void MMU2::mmu_loop() {
 
     case -2:
       if (rx_ok()) {
-        sscanf(rx_buffer, "%huok\n", &version);
+        const uint16_t version = uint16_t(strtoul(rx_buffer, nullptr, 10));
         DEBUG_ECHOLNPGM("MMU => ", version, "\nMMU <= 'S2'");
         MMU2_SEND("S2");    // Read Build Number
         state = -3;
@@ -177,17 +177,15 @@ void MMU2::mmu_loop() {
 
     case -3:
       if (rx_ok()) {
-        sscanf(rx_buffer, "%huok\n", &buildnr);
-
+        const uint16_t buildnr = uint16_t(strtoul(rx_buffer, nullptr, 10));
         DEBUG_ECHOLNPGM("MMU => ", buildnr);
 
-        check_version();
+        check_version(buildnr);
 
         #if ENABLED(MMU2_MODE_12V)
           DEBUG_ECHOLNPGM("MMU <= 'M1'");
           MMU2_SEND("M1");    // Stealth Mode
           state = -5;
-
         #else
           DEBUG_ECHOLNPGM("MMU <= 'P0'");
           MMU2_SEND("P0");    // Read FINDA
@@ -210,7 +208,8 @@ void MMU2::mmu_loop() {
 
     case -4:
       if (rx_ok()) {
-        sscanf(rx_buffer, "%hhuok\n", &finda);
+        const uint8_t findex = uint8_t(rx_buffer[0] - '0');
+        if (findex <= 1) finda = findex;
 
         DEBUG_ECHOLNPGM("MMU => ", finda, "\nMMU - ENABLED");
 
@@ -283,7 +282,8 @@ void MMU2::mmu_loop() {
 
     case 2:   // response to command P0
       if (rx_ok()) {
-        sscanf(rx_buffer, "%hhuok\n", &finda);
+        const uint8_t findex = uint8_t(rx_buffer[0] - '0');
+        if (findex <= 1) finda = findex;
 
         // This is super annoying. Only activate if necessary
         //if (finda_runout_valid) DEBUG_ECHOLNPGM("MMU <= 'P0'\nMMU => ", p_float_t(finda, 6));
@@ -439,7 +439,7 @@ bool MMU2::rx_ok() {
 /**
  * Check if MMU has compatible firmware
  */
-void MMU2::check_version() {
+void MMU2::check_version(const uint16_t buildnr) {
   if (buildnr < MMU_REQUIRED_FW_BUILDNR) {
     SERIAL_ERROR_MSG("Invalid MMU2 firmware. Version >= " STRINGIFY(MMU_REQUIRED_FW_BUILDNR) " required.");
     kill(GET_TEXT_F(MSG_KILL_MMU2_FIRMWARE));
@@ -801,8 +801,7 @@ bool MMU2::get_response() {
 void MMU2::manage_response(const bool move_axes, const bool turn_off_nozzle) {
 
   constexpr xyz_pos_t park_point = NOZZLE_PARK_POINT;
-  bool response = false;
-  mmu_print_saved = false;
+  bool response = false, mmu_print_saved = false;
   xyz_pos_t resume_position;
   celsius_t resume_hotend_temp = thermalManager.degTargetHotend(active_extruder);
 

Marlin/src/feature/mmu/mmu2.h

@@ -64,7 +64,7 @@ class MMU2 {
 
   static bool rx_ok();
   static bool rx_start();
-  static void check_version();
+  static void check_version(const uint16_t buildnr);
 
   static void command(const uint8_t cmd);
   static bool get_response();
@@ -90,13 +90,12 @@ class MMU2 {
     static void mmu_continue_loading();
   #endif
 
-  static bool _enabled, ready, mmu_print_saved;
+  static bool _enabled, ready;
 
   static uint8_t cmd, cmd_arg, last_cmd, extruder;
   static int8_t state;
   static volatile int8_t finda;
   static volatile bool finda_runout_valid;
-  static uint16_t version, buildnr;
   static millis_t prev_request, prev_P0_request;
   static char rx_buffer[MMU_RX_SIZE], tx_buffer[MMU_TX_SIZE];