Optimized string-to-number functions (#21484)

Marlin/src/gcode/parser.cpp

@@ -28,6 +28,146 @@
 
 #include "../MarlinCore.h"
 
+#ifdef __AVR__
+
+  static FORCE_INLINE uint32_t mult10(uint32_t val) {
+    uint32_t tmp = val;
+    __asm__ __volatile__ (
+       "add %A[tmp], %A[tmp]\n"
+       "adc %B[tmp], %B[tmp]\n"
+       "adc %C[tmp], %C[tmp]\n"
+       "adc %D[tmp], %D[tmp]\n"
+       "add %A[tmp], %A[tmp]\n"
+       "adc %B[tmp], %B[tmp]\n"
+       "adc %C[tmp], %C[tmp]\n"
+       "adc %D[tmp], %D[tmp]\n"
+       "add %A[val], %A[tmp]\n"
+       "adc %B[val], %B[tmp]\n"
+       "adc %C[val], %C[tmp]\n"
+       "adc %D[val], %D[tmp]\n"
+       "add %A[val], %A[val]\n"
+       "adc %B[val], %B[val]\n"
+       "adc %C[val], %C[val]\n"
+       "adc %D[val], %D[val]\n"
+        : [val] "+&r" (val),
+          [tmp] "+&r" (tmp)
+    );
+    return val;
+  }
+
+#else
+
+  static FORCE_INLINE uint32_t mult10(uint32_t val) { return val * 10; }
+
+#endif
+
+// cheap base-10 strto(u)l.
+// does not check for errors.
+int32_t parse_int32(const char *buf) {
+  char c;
+
+  // Get a char, skipping leading spaces
+  do { c = *buf++; } while (c == ' ');
+
+  // check for sign
+  bool is_negative = (c == '-');
+  if (is_negative || c == '+')
+    c = *buf++;
+
+  // optimization for first digit (no multiplication)
+  uint8_t uc = c - '0';
+  if (uc > 9) return 0;
+
+  // read unsigned value
+  uint32_t uval = uc;
+  while (true) {
+    c = *buf++;
+    uc = c - '0';
+    if (uc > 9) break;
+    uval = mult10(uval) + uc;
+  }
+
+  return is_negative ? -uval : uval;
+}
+
+// cheap strtof.
+// does not support nan/infinity or exponent notation.
+// does not check for errors.
+float parse_float(const char *buf) {
+  char c;
+
+  // Get a char, skipping leading spaces
+  do { c = *buf++; } while (c == ' ');
+
+  // check for sign
+  bool is_negative = (c == '-');
+  if (is_negative || c == '+')
+    c = *buf++;
+
+  // read unsigned value and decimal point
+  uint32_t uval;
+  uint8_t exp_dec;
+  uint8_t uc = c - '0';
+  if (uc <= 9) {
+    uval = uc;
+    exp_dec = 0;
+  }
+  else {
+    if (c != '.') return 0;
+    uval = 0;
+    exp_dec = 1;
+  }
+
+  int8_t exp = 0;
+  while (true) {
+    c = *buf++;
+    uc = c - '0';
+    if (uc <= 9) {
+      exp -= exp_dec;
+      uval = mult10(uval) + uc;
+      if (uval >= (UINT32_MAX - 9) / 10) {
+        // overflow. keep reading digits until decimal point.
+        while (exp_dec == 0) {
+          c = *buf++;
+          uc = c - '0';
+          if (uc > 9) break;
+          exp++;
+        }
+        goto overflow;
+      }
+    }
+    else {
+      if (c != '.' || exp_dec != 0) break;
+      exp_dec = 1;
+    }
+  }
+
+  // early return for 0
+  if (uval == 0) return 0;
+
+  overflow:
+
+  // convert to float and apply sign
+  float fval = uval;
+  if (is_negative) fval *= -1;
+
+  // apply exponent (up to 1e-15 / 1e+15)
+  if (exp < 0) {
+    if (exp <= -8) { fval *= 1e-8; exp += 8; }
+    if (exp <= -4) { fval *= 1e-4; exp += 4; }
+    if (exp <= -2) { fval *= 1e-2; exp += 2; }
+    if (exp <= -1) { fval *= 1e-1; exp += 1; }
+  }
+  else if (exp > 0) {
+    if (exp >= 8) { fval *= 1e+8; exp -= 8; }
+    if (exp >= 4) { fval *= 1e+4; exp -= 4; }
+    if (exp >= 2) { fval *= 1e+2; exp -= 2; }
+    if (exp >= 1) { fval *= 1e+1; exp -= 1; }
+  }
+
+  return fval;
+}
+
 // Must be declared for allocation and to satisfy the linker
 // Zero values need no initialization.
 

Marlin/src/gcode/parser.h

@@ -42,6 +42,10 @@
   typedef enum : uint8_t { LINEARUNIT_MM, LINEARUNIT_INCH } LinearUnit;
 #endif
 
+
+int32_t parse_int32(const char *buf);
+float parse_float(const char *buf);
+
 /**
  * GCode parser
  *
@@ -256,29 +260,12 @@ public:
   // The value as a string
   static inline char* value_string() { return value_ptr; }
 
-  // Float removes 'E' to prevent scientific notation interpretation
-  static inline float value_float() {
-    if (value_ptr) {
-      char *e = value_ptr;
-      for (;;) {
-        const char c = *e;
-        if (c == '\0' || c == ' ') break;
-        if (c == 'E' || c == 'e') {
-          *e = '\0';
-          const float ret = strtof(value_ptr, nullptr);
-          *e = c;
-          return ret;
-        }
-        ++e;
-      }
-      return strtof(value_ptr, nullptr);
-    }
-    return 0;
-  }
+  // Code value as float
+  static inline float value_float() { return value_ptr ? parse_float(value_ptr) : 0.0; }
 
   // Code value as a long or ulong
-  static inline int32_t value_long() { return value_ptr ? strtol(value_ptr, nullptr, 10) : 0L; }
-  static inline uint32_t value_ulong() { return value_ptr ? strtoul(value_ptr, nullptr, 10) : 0UL; }
+  static inline int32_t value_long() { return value_ptr ? parse_int32(value_ptr) : 0L; }
+  static inline uint32_t value_ulong() { return value_ptr ? parse_int32(value_ptr) : 0UL; }
 
   // Code value for use as time
   static inline millis_t value_millis() { return value_ulong(); }

Marlin/src/gcode/queue.cpp

@@ -459,7 +459,7 @@ void GCodeQueue::get_serial_commands() {
             if (n2pos) npos = n2pos;
           }
 
-          const long gcode_N = strtol(npos + 1, nullptr, 10);
+          const long gcode_N = parse_int32(npos + 1);
 
           if (gcode_N != serial.last_N + 1 && !M110) {
             // In case of error on a serial port, don't prevent other serial port from making progress
@@ -471,7 +471,7 @@ void GCodeQueue::get_serial_commands() {
           if (apos) {
             uint8_t checksum = 0, count = uint8_t(apos - command);
             while (count) checksum ^= command[--count];
-            if (strtol(apos + 1, nullptr, 10) != checksum) {
+            if (parse_int32(apos + 1) != checksum) {
               // In case of error on a serial port, don't prevent other serial port from making progress
               gcode_line_error(PSTR(STR_ERR_CHECKSUM_MISMATCH), p);
               break;
@@ -500,7 +500,7 @@ void GCodeQueue::get_serial_commands() {
         if (IsStopped()) {
           char* gpos = strchr(command, 'G');
           if (gpos) {
-            switch (strtol(gpos + 1, nullptr, 10)) {
+            switch (parse_int32(gpos + 1)) {
               case 0: case 1:
               #if ENABLED(ARC_SUPPORT)
                 case 2: case 3:

Marlin/src/lcd/extui/lib/mks_ui/wifi_module.cpp

@@ -1799,7 +1799,7 @@ void get_wifi_commands() {
           if (IsStopped()) {
           char* gpos = strchr(command, 'G');
           if (gpos) {
-            switch (strtol(gpos + 1, nullptr, 10)) {
+            switch (parse_int32(gpos + 1)) {
               case 0 ... 1:
               #if ENABLED(ARC_SUPPORT)
                 case 2 ... 3: