nuts_bolts.c

/*
  nuts_bolts.c - Shared functions
  Part of Grbl

  The MIT License (MIT)

  GRBL(tm) - Embedded CNC g-code interpreter and motion-controller
  Copyright (c) 2009-2011 Simen Svale Skogsrud
  Copyright (c) 2011-2012 Sungeun K. Jeon

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  THE SOFTWARE.
*/

#include <util/delay.h>
#include "nuts_bolts.h"
#include "gcode.h"
#include "planner.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().
int 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);
}


// 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;
    }
  }
}

// Syncs all internal position vectors to the current system position.
void sys_sync_current_position()
{
  plan_set_current_position(sys.position[X_AXIS],sys.position[Y_AXIS],sys.position[Z_AXIS]);
  gc_set_current_position(sys.position[X_AXIS],sys.position[Y_AXIS],sys.position[Z_AXIS]);
}