//------------------------------------------------------------------------------
// 2 Axis CNC Demo
// dan@marginallyclever.com 2013-08-30
//------------------------------------------------------------------------------
// Copyright at end of file.
// please see http://www.github.com/MarginallyClever/GcodeCNCDemo for more information.

#include "config.h"

//------------------------------------------------------------------------------
// GLOBALS
//------------------------------------------------------------------------------

char  serialBuffer[MAX_BUF];  // where we store the message until we get a newline
int   sofar;            // how much is in the serialBuffer
float px, py;      // location

// speeds
float fr =     0;  // human version
long  step_delay;  // machine version

// settings
char mode_abs=1;   // absolute mode?


//------------------------------------------------------------------------------
// METHODS
//------------------------------------------------------------------------------


/**
 * delay for the appropriate number of microseconds
 * @input ms how many milliseconds to wait
 */
void pause(long ms) {
  delay(ms/1000);
  delayMicroseconds(ms%1000);  // delayMicroseconds doesn't work for values > ~16k.
}


/**
 * Set the feedrate (speed motors will move)
 * @input nfr the new speed in steps/second
 */
void feedrate(float nfr) {
  if(fr==nfr) return;  // same as last time?  quit now.

  if(nfr>MAX_FEEDRATE || nfr<MIN_FEEDRATE) {  // don't allow crazy feed rates
    Serial.print(F("New feedrate must be greater than "));
    Serial.print(MIN_FEEDRATE);
    Serial.print(F("steps/s and less than "));
    Serial.print(MAX_FEEDRATE);
    Serial.println(F("steps/s."));
    return;
  }
  step_delay = 1000000.0/nfr;
  fr = nfr;
}


/**
 * Set the logical position
 * @input npx new position x
 * @input npy new position y
 */
void position(float npx,float npy) {
  // here is a good place to add sanity tests
  px=npx;
  py=npy;
}


/**
 * Uses bresenham's line algorithm to move both motors
 * @input newx the destination x position
 * @input newy the destination y position
 **/
void line(float newx,float newy) {
  long i;
  long over= 0;
  
  long dx  = newx-px;
  long dy  = newy-py;
  int dirx = dx>0?1:-1;
  #ifdef INVERT_Y
  int diry = dy>0?-1:1;  // because the motors are mounted in opposite directions
  #else
  int diry = dy>0?1:-1;
  #endif
  dx = abs(dx);
  dy = abs(dy);

  if(dx>dy) {
    over = dx/2;
    for(i=0; i<dx; ++i) {
      m1step(dirx);
      over += dy;
      if(over>=dx) {
        over -= dx;
        m2step(diry);
      }
      pause(step_delay);
    }
  } else {
    over = dy/2;
    for(i=0; i<dy; ++i) {
      m2step(diry);
      over += dx;
      if(over >= dy) {
        over -= dy;
        m1step(dirx);
      }
      pause(step_delay);
    }
  }

  px = newx;
  py = newy;
}


// returns angle of dy/dx as a value from 0...2PI
float atan3(float dy,float dx) {
  float a = atan2(dy,dx);
  if(a<0) a = (PI*2.0)+a;
  return a;
}


// This method assumes the limits have already been checked.
// This method assumes the start and end radius match.
// This method assumes arcs are not >180 degrees (PI radians)
// cx/cy - center of circle
// x/y - end position
// dir - ARC_CW or ARC_CCW to control direction of arc
void arc(float cx,float cy,float x,float y,float dir) {
  // get radius
  float dx = px - cx;
  float dy = py - cy;
  float radius=sqrt(dx*dx+dy*dy);

  // find angle of arc (sweep)
  float angle1=atan3(dy,dx);
  float angle2=atan3(y-cy,x-cx);
  float theta=angle2-angle1;
  
  if(dir>0 && theta<0) angle2+=2*PI;
  else if(dir<0 && theta>0) angle1+=2*PI;
  
  theta=angle2-angle1;
  
  // get length of arc
  // float circ=PI*2.0*radius;
  // float len=theta*circ/(PI*2.0);
  // simplifies to
  float len = abs(theta) * radius;

  int i, segments = ceil( len * MM_PER_SEGMENT );
 
  float nx, ny, angle3, scale;

  for(i=0;i<segments;++i) {
    // interpolate around the arc
    scale = ((float)i)/((float)segments);
    
    angle3 = ( theta * scale ) + angle1;
    nx = cx + cos(angle3) * radius;
    ny = cy + sin(angle3) * radius;
    // send it to the planner
    line(nx,ny);
  }
  
  line(x,y);
}


/**
 * Look for character /code/ in the buffer and read the float that immediately follows it.
 * @return the value found.  If nothing is found, /val/ is returned.
 * @input code the character to look for.
 * @input val the return value if /code/ is not found.
 **/
float parseNumber(char code,float val) {
  char *ptr=serialBuffer;  // start at the beginning of buffer
  while((long)ptr > 1 && (*ptr) && (long)ptr < (long)serialBuffer+sofar) {  // walk to the end
    if(*ptr==code) {  // if you find code on your walk,
      return atof(ptr+1);  // convert the digits that follow into a float and return it
    }
    ptr=strchr(ptr,' ')+1;  // take a step from here to the letter after the next space
  }
  return val;  // end reached, nothing found, return default val.
}


/**
 * write a string followed by a float to the serial line.  Convenient for debugging.
 * @input code the string.
 * @input val the float.
 */
void output(const char *code,float val) {
  Serial.print(code);
  Serial.println(val);
}


/**
 * print the current position, feedrate, and absolute mode.
 */
void where() {
  output("X",px);
  output("Y",py);
  output("F",fr);
  Serial.println(mode_abs?"ABS":"REL");
} 


/**
 * display helpful information
 */
void help() {
  Serial.print(F("GcodeCNCDemo2AxisV1 "));
  Serial.println(VERSION);
  Serial.println(F("Commands:"));
  Serial.println(F("G00 [X(steps)] [Y(steps)] [F(feedrate)]; - line"));
  Serial.println(F("G01 [X(steps)] [Y(steps)] [F(feedrate)]; - line"));
  Serial.println(F("G02 [X(steps)] [Y(steps)] [I(steps)] [J(steps)] [F(feedrate)]; - clockwise arc"));
  Serial.println(F("G03 [X(steps)] [Y(steps)] [I(steps)] [J(steps)] [F(feedrate)]; - counter-clockwise arc"));
  Serial.println(F("G04 P[seconds]; - delay"));
  Serial.println(F("G90; - absolute mode"));
  Serial.println(F("G91; - relative mode"));
  Serial.println(F("G92 [X(steps)] [Y(steps)]; - change logical position"));
  Serial.println(F("M18; - disable motors"));
  Serial.println(F("M100; - this help message"));
  Serial.println(F("M114; - report position and feedrate"));
  Serial.println(F("All commands must end with a newline."));
}


/**
 * Read the input buffer and find any recognized commands.  One G or M command per line.
 */
void processCommand() {
  int cmd = parseNumber('G',-1);
  switch(cmd) {
  case  0:
  case  1: { // line
    feedrate(parseNumber('F',fr));
    line( parseNumber('X',(mode_abs?px:0)) + (mode_abs?0:px),
          parseNumber('Y',(mode_abs?py:0)) + (mode_abs?0:py) );
    break;
    }
  case 2:
  case 3: {  // arc
      feedrate(parseNumber('F',fr));
      arc(parseNumber('I',(mode_abs?px:0)) + (mode_abs?0:px),
          parseNumber('J',(mode_abs?py:0)) + (mode_abs?0:py),
          parseNumber('X',(mode_abs?px:0)) + (mode_abs?0:px),
          parseNumber('Y',(mode_abs?py:0)) + (mode_abs?0:py),
          (cmd==2) ? -1 : 1);
      break;
    }
  case  4:  pause(parseNumber('P',0)*1000);  break;  // dwell
  case 90:  mode_abs=1;  break;  // absolute mode
  case 91:  mode_abs=0;  break;  // relative mode
  case 92:  // set logical position
    position( parseNumber('X',0),
              parseNumber('Y',0) );
    break;
  default:  break;
  }

  cmd = parseNumber('M',-1);
  switch(cmd) {
  case 18:  // disable motors
    disable();
    break;
  case 100:  help();  break;
  case 114:  where();  break;
  default:  break;
  }
}


/**
 * prepares the input buffer to receive a new message and tells the serial connected device it is ready for more.
 */
void ready() {
  sofar=0;  // clear input buffer
  Serial.print(F(">"));  // signal ready to receive input
}


/**
 * First thing this machine does on startup.  Runs only once.
 */
void setup() {
  Serial.begin(BAUD);  // open coms

  setup_controller();  
  position(0,0);  // set staring position
  feedrate((MAX_FEEDRATE + MIN_FEEDRATE)/2);  // set default speed

  help();  // say hello
  ready();
}


/**
 * After setup() this machine will repeat loop() forever.
 */
void loop() {
  // listen for serial commands
  while(Serial.available() > 0) {  // if something is available
    char c=Serial.read();  // get it
    Serial.print(c);  // repeat it back so I know you got the message
    if(sofar<MAX_BUF-1) serialBuffer[sofar++]=c;  // store it
    if((c=='\n') || (c == '\r')) {
      // entire message received
      serialBuffer[sofar]=0;  // end the buffer so string functions work right
      Serial.print(F("\r\n"));  // echo a return character for humans
      processCommand();  // do something with the command
      ready();
    }
  }
}


/**
* This file is part of GcodeCNCDemo.
*
* GcodeCNCDemo 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.
*
* GcodeCNCDemo 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 Foobar. If not, see <http://www.gnu.org/licenses/>.
*/