dda.h

#ifndef _DDA_H
#define _DDA_H

#include <stdint.h>

#include "config_wrapper.h"

#ifdef ACCELERATION_REPRAP
  #ifdef ACCELERATION_RAMPING
    #error Cant use ACCELERATION_REPRAP and ACCELERATION_RAMPING together.
  #endif
#endif

// The distance of any move and a single axis should never go above this limit.
// Check move_duration and c_limit calculations in dda.c
#define MAX_DELTA_UM ((int32_t)(UINT32_MAX / 2400L))

// Enum to denote an axis
enum axis_e { X = 0, Y, Z, E, AXIS_COUNT };

/**
  \typedef axes_uint32_t
  \brief n-dimensional vector used to describe uint32_t axis information.

  Stored value can be anything unsigned. Units should be specified when declared.
*/
typedef uint32_t axes_uint32_t[AXIS_COUNT];

/**
  \typedef axes_int32_t
  \brief n-dimensional vector used to describe int32_t axis information.

  Stored value can be anything unsigned. Units should be specified when declared.
*/
typedef int32_t axes_int32_t[AXIS_COUNT];

/**
  \struct TARGET
  \brief target is simply a point in space/time

  X, Y, Z and E are in micrometers unless explcitely stated. F is in mm/min.
*/
typedef struct {
  axes_int32_t axis;
  uint32_t  F;

  uint16_t  e_multiplier;
  uint16_t  f_multiplier;
  uint8_t   e_relative        :1; ///< bool: e axis relative? Overrides all_relative
} TARGET;

/**
  \struct MOVE_STATE
  \brief this struct is made for tracking the current state of the movement

  Parts of this struct are initialised only once per reboot, so make sure dda_step() leaves them with a value compatible to begin a new movement at the end of the movement. Other parts are filled in by dda_start().
*/
typedef struct {
  // bresenham counters
  axes_int32_t      counter;    ///< counter for total_steps vs each axis

  #ifdef ACCELERATION_TEMPORAL
  axes_uint32_t     time;       ///< time of the last step on each axis
  uint32_t          last_time;  ///< time of the last step of any axis
  #endif

  axes_uint32_t     steps;      ///< number of steps on each axis
  /// Endstop handling.
  uint8_t endstop_stop;         ///< Stop due to endstop trigger
  uint8_t debounce_count_x, debounce_count_y, debounce_count_z;
} MOVE_STATE;

/**
  \struct DDA
  \brief this is a digital differential analyser data struct

  This struct holds all the details of an individual multi-axis move, including pre-calculated acceleration data.
  This struct is filled in by dda_create(), called from enqueue(), called mostly from gcode_process() and from a few other places too (eg \file homing.c)
*/
typedef struct {
  /// this is where we should finish
  TARGET            endpoint;

  union {
    struct {
      // status fields
      uint8_t           nullmove      :1; ///< bool: no axes move, maybe we wait for temperatures or change speed
      volatile uint8_t  live          :1; ///< bool: this DDA is running and still has steps to do
      uint8_t           done          :1; ///< bool: this DDA is done.
      #ifdef ACCELERATION_REPRAP
      uint8_t           accel         :1; ///< bool: speed changes during this move, run accel code
      #endif

      // directions
      // As we have muldiv() now, overflows became much less an issue and
      // it's likely time to get rid of these flags and use int instead of
      // uint for distance/speed calculations. --Traumflug 2014-07-04
      uint8_t           x_direction   :1; ///< direction flag for X axis
      uint8_t           y_direction   :1; ///< direction flag for Y axis
      uint8_t           z_direction   :1; ///< direction flag for Z axis
      uint8_t           e_direction   :1; ///< direction flag for E axis
    };
    uint16_t            allflags; ///< used for clearing all flags
  };

  // distances
  axes_uint32_t     delta;       ///< number of steps on each axis

  // uint8_t        fast_axis;   (see below)
  uint32_t          total_steps; ///< steps of the "fast" axis
  uint32_t          fast_um;     ///< movement length of this fast axis

  uint32_t          c; ///< time until next step, 24.8 fixed point

  #ifdef ACCELERATION_REPRAP
  uint32_t          end_c; ///< time between 2nd last step and last step
  int32_t           n;     ///< precalculated step time offset variable
  #endif
  #ifdef ACCELERATION_RAMPING
  /// precalculated step time offset variable
  int32_t           n;
  /// number of steps accelerating
  uint32_t          rampup_steps;
  /// number of last step before decelerating
  uint32_t          rampdown_steps;
  /// 24.8 fixed point timer value, maximum speed
  uint32_t          c_min;
  #ifdef LOOKAHEAD
  // With the look-ahead functionality, it is possible to retain physical
  // movement between G1 moves. These variables keep track of the entry and
  // exit speeds between moves.
  uint32_t          distance;
  uint32_t          crossF;
  // These two are based on the "fast" axis, the axis with the most steps.
  uint32_t          start_steps; ///< would be required to reach start feedrate
  uint32_t          end_steps; ///< would be required to stop from end feedrate
  #endif
  // Number the moves to be able to test at the end of lookahead if the moves
  // are the same. Note: we do not need a lot of granularity here: more than
  // MOVEBUFFER_SIZE is already enough.
  uint8_t           id;
  #endif
  #ifdef ACCELERATION_TEMPORAL
  axes_uint32_t     step_interval;   ///< time between steps on each axis
  uint8_t           axis_to_step;    ///< axis to be stepped on the next interrupt
  #endif

  /// Small variables. Many CPUs can access 32-bit variables at word or double
  /// word boundaries only and fill smaller variables in between with gaps,
  /// so keep small variables grouped together to reduce the amount of these
  /// gaps. See e.g. NXP application note AN10963, page 10f.
  uint8_t           fast_axis;       ///< number of the fast axis

  /// Endstop homing
  uint8_t endstop_check; ///< Do we need to check endstops? 0x1=Check X, 0x2=Check Y, 0x4=Check Z
  uint8_t endstop_stop_cond; ///< Endstop condition on which to stop motion: 0=Stop on detrigger, 1=Stop on trigger
} DDA;

/*
  variables
*/

/// startpoint holds the endpoint of the most recently created DDA, so we know where the next one created starts. could also be called last_endpoint
extern TARGET startpoint;

/// the same as above, counted in motor steps
extern TARGET startpoint_steps;

/// current_position holds the machine's current position. this is only updated when we step, or when G92 (set home) is received.
extern TARGET current_position;

/*
  methods
*/

int8_t get_direction(DDA *dda, enum axis_e n);

// initialize dda structures
void dda_init(void);

// distribute a new startpoint
void dda_new_startpoint(void);

// create a DDA
void dda_create(DDA *dda, const TARGET *target);

// start a created DDA (called from timer interrupt)
void dda_start(DDA *dda);

// DDA takes one step (called from timer interrupt)
void dda_step(DDA *dda);

// regular movement maintenance
void dda_clock(void);

// update current_position
void update_current_position(void);

#endif /* _DDA_H */