trapq: Add new trapq.c file with code for trapezoidal velocity handling

Move the "struct move" code from itersolve.c to new file trapq.c.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

1 files changed, 87 insertions, 0 deletions

diff --git a/klippy/chelper/trapq.c b/klippy/chelper/trapq.c
new file mode 100644
index 00000000..c17471e7
--- /dev/null
+++ b/klippy/chelper/trapq.c
@@ -0,0 +1,87 @@
+// Trapezoidal velocity movement queue
+//
+// Copyright (C) 2018-2019  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include <math.h> // sqrt
+#include <stdlib.h> // malloc
+#include <string.h> // memset
+#include "compiler.h" // unlikely
+#include "trapq.h" // move_get_coord
+
+struct move * __visible
+move_alloc(void)
+{
+    struct move *m = malloc(sizeof(*m));
+    memset(m, 0, sizeof(*m));
+    return m;
+}
+
+// Populate a 'struct move' with a velocity trapezoid
+void __visible
+move_fill(struct move *m, double print_time
+          , double accel_t, double cruise_t, double decel_t
+          , double start_pos_x, double start_pos_y, double start_pos_z
+          , double axes_d_x, double axes_d_y, double axes_d_z
+          , double start_v, double cruise_v, double accel)
+{
+    // Setup velocity trapezoid
+    m->print_time = print_time;
+    m->move_t = accel_t + cruise_t + decel_t;
+    m->accel_t = accel_t;
+    m->cruise_t = cruise_t;
+    m->cruise_start_d = accel_t * .5 * (cruise_v + start_v);
+    m->decel_start_d = m->cruise_start_d + cruise_t * cruise_v;
+
+    // Setup for accel/cruise/decel phases
+    m->cruise_v = cruise_v;
+    m->accel.c1 = start_v;
+    m->accel.c2 = .5 * accel;
+    m->decel.c1 = cruise_v;
+    m->decel.c2 = -m->accel.c2;
+
+    // Setup for move_get_coord()
+    m->start_pos.x = start_pos_x;
+    m->start_pos.y = start_pos_y;
+    m->start_pos.z = start_pos_z;
+    double inv_move_d = 1. / sqrt(axes_d_x*axes_d_x + axes_d_y*axes_d_y
+                                  + axes_d_z*axes_d_z);
+    m->axes_r.x = axes_d_x * inv_move_d;
+    m->axes_r.y = axes_d_y * inv_move_d;
+    m->axes_r.z = axes_d_z * inv_move_d;
+}
+
+// Find the distance travel during acceleration/deceleration
+static inline double
+move_eval_accel(struct move_accel *ma, double move_time)
+{
+    return (ma->c1 + ma->c2 * move_time) * move_time;
+}
+
+// Return the distance moved given a time in a move
+inline double
+move_get_distance(struct move *m, double move_time)
+{
+    if (unlikely(move_time < m->accel_t))
+        // Acceleration phase of move
+        return move_eval_accel(&m->accel, move_time);
+    move_time -= m->accel_t;
+    if (likely(move_time <= m->cruise_t))
+        // Cruising phase
+        return m->cruise_start_d + m->cruise_v * move_time;
+    // Deceleration phase
+    move_time -= m->cruise_t;
+    return m->decel_start_d + move_eval_accel(&m->decel, move_time);
+}
+
+// Return the XYZ coordinates given a time in a move
+inline struct coord
+move_get_coord(struct move *m, double move_time)
+{
+    double move_dist = move_get_distance(m, move_time);
+    return (struct coord) {
+        .x = m->start_pos.x + m->axes_r.x * move_dist,
+        .y = m->start_pos.y + m->axes_r.y * move_dist,
+        .z = m->start_pos.z + m->axes_r.z * move_dist };
+}