Import grbl v1.1h
diff --git a/grbl/nuts_bolts.c b/grbl/nuts_bolts.c
new file mode 100644
index 0000000..9d89a8d
--- /dev/null
+++ b/grbl/nuts_bolts.c
@@ -0,0 +1,190 @@
+/*
+  nuts_bolts.c - Shared functions
+  Part of Grbl
+
+  Copyright (c) 2011-2016 Sungeun K. Jeon for Gnea Research LLC
+  Copyright (c) 2009-2011 Simen Svale Skogsrud
+
+  Grbl is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Grbl is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with Grbl.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "grbl.h"
+
+
+#define MAX_INT_DIGITS 8 // Maximum number of digits in int32 (and float)
+
+
+// Extracts a floating point value from a string. The following code is based loosely on
+// the avr-libc strtod() function by Michael Stumpf and Dmitry Xmelkov and many freely
+// available conversion method examples, but has been highly optimized for Grbl. For known
+// CNC applications, the typical decimal value is expected to be in the range of E0 to E-4.
+// Scientific notation is officially not supported by g-code, and the 'E' character may
+// be a g-code word on some CNC systems. So, 'E' notation will not be recognized.
+// NOTE: Thanks to Radu-Eosif Mihailescu for identifying the issues with using strtod().
+uint8_t read_float(char *line, uint8_t *char_counter, float *float_ptr)
+{
+  char *ptr = line + *char_counter;
+  unsigned char c;
+
+  // Grab first character and increment pointer. No spaces assumed in line.
+  c = *ptr++;
+
+  // Capture initial positive/minus character
+  bool isnegative = false;
+  if (c == '-') {
+    isnegative = true;
+    c = *ptr++;
+  } else if (c == '+') {
+    c = *ptr++;
+  }
+
+  // Extract number into fast integer. Track decimal in terms of exponent value.
+  uint32_t intval = 0;
+  int8_t exp = 0;
+  uint8_t ndigit = 0;
+  bool isdecimal = false;
+  while(1) {
+    c -= '0';
+    if (c <= 9) {
+      ndigit++;
+      if (ndigit <= MAX_INT_DIGITS) {
+        if (isdecimal) { exp--; }
+        intval = (((intval << 2) + intval) << 1) + c; // intval*10 + c
+      } else {
+        if (!(isdecimal)) { exp++; }  // Drop overflow digits
+      }
+    } else if (c == (('.'-'0') & 0xff)  &&  !(isdecimal)) {
+      isdecimal = true;
+    } else {
+      break;
+    }
+    c = *ptr++;
+  }
+
+  // Return if no digits have been read.
+  if (!ndigit) { return(false); };
+
+  // Convert integer into floating point.
+  float fval;
+  fval = (float)intval;
+
+  // Apply decimal. Should perform no more than two floating point multiplications for the
+  // expected range of E0 to E-4.
+  if (fval != 0) {
+    while (exp <= -2) {
+      fval *= 0.01;
+      exp += 2;
+    }
+    if (exp < 0) {
+      fval *= 0.1;
+    } else if (exp > 0) {
+      do {
+        fval *= 10.0;
+      } while (--exp > 0);
+    }
+  }
+
+  // Assign floating point value with correct sign.
+  if (isnegative) {
+    *float_ptr = -fval;
+  } else {
+    *float_ptr = fval;
+  }
+
+  *char_counter = ptr - line - 1; // Set char_counter to next statement
+
+  return(true);
+}
+
+
+// Non-blocking delay function used for general operation and suspend features.
+void delay_sec(float seconds, uint8_t mode)
+{
+ 	uint16_t i = ceil(1000/DWELL_TIME_STEP*seconds);
+	while (i-- > 0) {
+		if (sys.abort) { return; }
+		if (mode == DELAY_MODE_DWELL) {
+			protocol_execute_realtime();
+		} else { // DELAY_MODE_SYS_SUSPEND
+		  // Execute rt_system() only to avoid nesting suspend loops.
+		  protocol_exec_rt_system();
+		  if (sys.suspend & SUSPEND_RESTART_RETRACT) { return; } // Bail, if safety door reopens.
+		}
+		_delay_ms(DWELL_TIME_STEP); // Delay DWELL_TIME_STEP increment
+	}
+}
+
+
+// Delays variable defined milliseconds. Compiler compatibility fix for _delay_ms(),
+// which only accepts constants in future compiler releases.
+void delay_ms(uint16_t ms)
+{
+  while ( ms-- ) { _delay_ms(1); }
+}
+
+
+// Delays variable defined microseconds. Compiler compatibility fix for _delay_us(),
+// which only accepts constants in future compiler releases. Written to perform more
+// efficiently with larger delays, as the counter adds parasitic time in each iteration.
+void delay_us(uint32_t us)
+{
+  while (us) {
+    if (us < 10) {
+      _delay_us(1);
+      us--;
+    } else if (us < 100) {
+      _delay_us(10);
+      us -= 10;
+    } else if (us < 1000) {
+      _delay_us(100);
+      us -= 100;
+    } else {
+      _delay_ms(1);
+      us -= 1000;
+    }
+  }
+}
+
+
+// Simple hypotenuse computation function.
+float hypot_f(float x, float y) { return(sqrt(x*x + y*y)); }
+
+
+float convert_delta_vector_to_unit_vector(float *vector)
+{
+  uint8_t idx;
+  float magnitude = 0.0;
+  for (idx=0; idx<N_AXIS; idx++) {
+    if (vector[idx] != 0.0) {
+      magnitude += vector[idx]*vector[idx];
+    }
+  }
+  magnitude = sqrt(magnitude);
+  float inv_magnitude = 1.0/magnitude;
+  for (idx=0; idx<N_AXIS; idx++) { vector[idx] *= inv_magnitude; }
+  return(magnitude);
+}
+
+
+float limit_value_by_axis_maximum(float *max_value, float *unit_vec)
+{
+  uint8_t idx;
+  float limit_value = SOME_LARGE_VALUE;
+  for (idx=0; idx<N_AXIS; idx++) {
+    if (unit_vec[idx] != 0) {  // Avoid divide by zero.
+      limit_value = min(limit_value,fabs(max_value[idx]/unit_vec[idx]));
+    }
+  }
+  return(limit_value);
+}