Push old dev_2 draft to work on other things.

- **NON-FUNCTIONAL**
- Contains an old draft of separating the stepper driver direct access
to the planner buffer. This is designed to keep the stepper and planner
modules independent and prevent overwriting or other complications. In
this way, feedrate override should be able to be installed as well.
- A number of planner optimizations are installed too.
- Not sure where the bugs are. Either in the new planner optimizations,
new stepper module updates, or in both. Or it just could be that the
Arduino AVR is choking with the new things it has to do.

planner.h

@@ -2,8 +2,8 @@
   planner.h - buffers movement commands and manages the acceleration profile plan
   Part of Grbl
 
+  Copyright (c) 2011-2013 Sungeun K. Jeon 
   Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2013 Sungeun K. Jeon  
 
   Grbl is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -21,10 +21,11 @@
 
 #ifndef planner_h
 #define planner_h
-                 
+#include "nuts_bolts.h"
+
 // The number of linear motions that can be in the plan at any give time
 #ifndef BLOCK_BUFFER_SIZE
-  #define BLOCK_BUFFER_SIZE 17
+  #define BLOCK_BUFFER_SIZE 18
 #endif
 
 // This struct is used when buffering the setup for each linear movement "nominal" values are as specified in 
@@ -32,43 +33,43 @@
 typedef struct {
 
   // Fields used by the bresenham algorithm for tracing the line
-  uint8_t  direction_bits;            // The direction bit set for this block (refers to *_DIRECTION_BIT in config.h)
-  uint32_t steps_x, steps_y, steps_z; // Step count along each axis
-  int32_t  step_event_count;          // The number of step events required to complete this block
+  uint8_t direction_bits;            // The direction bit set for this block (refers to *_DIRECTION_BIT in config.h)
+  int32_t steps[N_AXIS];             // Step count along each axis
+  int32_t step_event_count;          // The number of step events required to complete this block
 
   // Fields used by the motion planner to manage acceleration
-  float nominal_speed_sqr;           // The nominal speed for this block in mm/min  
-  float entry_speed_sqr;             // Entry speed at previous-current block junction in mm/min
-  float max_entry_speed_sqr;         // Maximum allowable junction entry speed in mm/min
-  float millimeters;                 // The total travel of this block in mm
-  float acceleration;
-  uint8_t recalculate_flag;          // Planner flag to recalculate trapezoids on entry junction
-
+  float nominal_speed_sqr;           // Axis-limit adjusted nominal speed for this block in (mm/min)^2
+  float entry_speed_sqr;             // Entry speed at previous-current block junction in (mm/min)^2
+  float max_entry_speed_sqr;         // Maximum allowable junction entry speed in (mm/min)^2
+  float acceleration;                // Axes-limit adjusted line acceleration in mm/min^2
+  float millimeters;                 // The total travel for this block to be executed in mm
+  
   // Settings for the trapezoid generator
-  uint32_t initial_rate;              // The step rate at start of block  
-  int32_t rate_delta;                 // The steps/minute to add or subtract when changing speed (must be positive)
-  uint32_t decelerate_after;          // The index of the step event on which to start decelerating
-  uint32_t nominal_rate;              // The nominal step rate for this block in step_events/minute
-  uint32_t d_next;                    // Scaled distance to next step
-} block_t;
+//   int32_t decelerate_after;  // The index of the step event on which to start decelerating
+
+} plan_block_t;
       
 // Initialize the motion plan subsystem
 void plan_init();
 
-// Add a new linear movement to the buffer. x, y and z is the signed, absolute target position in 
-// millimaters. Feed rate specifies the speed of the motion. If feed rate is inverted, the feed
+// Add a new linear movement to the buffer. target[N_AXIS] is the signed, absolute target position 
+// in millimeters. Feed rate specifies the speed of the motion. If feed rate is inverted, the feed
 // rate is taken to mean "frequency" and would complete the operation in 1/feed_rate minutes.
-void plan_buffer_line(float x, float y, float z, float feed_rate, uint8_t invert_feed_rate);
+void plan_buffer_line(float *target, float feed_rate, uint8_t invert_feed_rate);
 
 // Called when the current block is no longer needed. Discards the block and makes the memory
 // availible for new blocks.
 void plan_discard_current_block();
 
 // Gets the current block. Returns NULL if buffer empty
-block_t *plan_get_current_block();
+plan_block_t *plan_get_current_block();
+
+plan_block_t *plan_get_block_by_index(uint8_t block_index);
+
+int32_t calculate_trapezoid_for_block(uint8_t block_index);
 
 // Reset the planner position vector (in steps)
-void plan_set_current_position(int32_t x, int32_t y, int32_t z);
+void plan_sync_position();
 
 // Reinitialize plan with a partially completed block
 void plan_cycle_reinitialize(int32_t step_events_remaining);