237 lines
7.2 KiB
C
237 lines
7.2 KiB
C
// Trapezoidal velocity movement queue
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//
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// Copyright (C) 2018-2019 Kevin O'Connor <kevin@koconnor.net>
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//
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// This file may be distributed under the terms of the GNU GPLv3 license.
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#include <math.h> // sqrt
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#include <stddef.h> // offsetof
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#include <stdlib.h> // malloc
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#include <string.h> // memset
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#include "compiler.h" // unlikely
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#include "trapq.h" // move_get_coord
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// Allocate a new 'move' object
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struct move *
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move_alloc(void)
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{
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struct move *m = malloc(sizeof(*m));
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memset(m, 0, sizeof(*m));
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return m;
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}
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// Fill and add a move to the trapezoid velocity queue
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void __visible
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trapq_append(struct trapq *tq, double print_time
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, double accel_t, double cruise_t, double decel_t
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, double start_pos_x, double start_pos_y, double start_pos_z
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, double axes_r_x, double axes_r_y, double axes_r_z
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, double start_v, double cruise_v, double accel)
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{
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struct coord start_pos = { .x=start_pos_x, .y=start_pos_y, .z=start_pos_z };
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struct coord axes_r = { .x=axes_r_x, .y=axes_r_y, .z=axes_r_z };
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if (accel_t) {
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struct move *m = move_alloc();
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m->print_time = print_time;
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m->move_t = accel_t;
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m->start_v = start_v;
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m->half_accel = .5 * accel;
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m->start_pos = start_pos;
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m->axes_r = axes_r;
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trapq_add_move(tq, m);
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print_time += accel_t;
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start_pos = move_get_coord(m, accel_t);
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}
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if (cruise_t) {
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struct move *m = move_alloc();
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m->print_time = print_time;
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m->move_t = cruise_t;
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m->start_v = cruise_v;
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m->half_accel = 0.;
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m->start_pos = start_pos;
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m->axes_r = axes_r;
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trapq_add_move(tq, m);
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print_time += cruise_t;
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start_pos = move_get_coord(m, cruise_t);
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}
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if (decel_t) {
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struct move *m = move_alloc();
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m->print_time = print_time;
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m->move_t = decel_t;
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m->start_v = cruise_v;
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m->half_accel = -.5 * accel;
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m->start_pos = start_pos;
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m->axes_r = axes_r;
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trapq_add_move(tq, m);
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}
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}
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// Return the distance moved given a time in a move
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inline double
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move_get_distance(struct move *m, double move_time)
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{
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return (m->start_v + m->half_accel * move_time) * move_time;
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}
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// Return the XYZ coordinates given a time in a move
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inline struct coord
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move_get_coord(struct move *m, double move_time)
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{
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double move_dist = move_get_distance(m, move_time);
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return (struct coord) {
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.x = m->start_pos.x + m->axes_r.x * move_dist,
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.y = m->start_pos.y + m->axes_r.y * move_dist,
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.z = m->start_pos.z + m->axes_r.z * move_dist };
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}
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// Helper code for integrating acceleration
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static double
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integrate_accel(struct move *m, double start, double end)
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{
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double half_v = .5 * m->start_v, sixth_a = (1. / 3.) * m->half_accel;
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double si = start * start * (half_v + sixth_a * start);
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double ei = end * end * (half_v + sixth_a * end);
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return ei - si;
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}
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// Calculate the definitive integral on part of a move
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static double
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move_integrate(struct move *m, int axis, double start, double end)
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{
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if (start < 0.)
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start = 0.;
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if (end > m->move_t)
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end = m->move_t;
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double base = m->start_pos.axis[axis - 'x'] * (end - start);
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double integral = integrate_accel(m, start, end);
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return base + integral * m->axes_r.axis[axis - 'x'];
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}
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// Calculate the definitive integral for a cartesian axis
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double
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trapq_integrate(struct move *m, int axis, double start, double end)
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{
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double res = move_integrate(m, axis, start, end);
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// Integrate over previous moves
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struct move *prev = m;
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while (unlikely(start < 0.)) {
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prev = list_prev_entry(prev, node);
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start += prev->move_t;
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res += move_integrate(prev, axis, start, prev->move_t);
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}
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// Integrate over future moves
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while (unlikely(end > m->move_t)) {
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end -= m->move_t;
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m = list_next_entry(m, node);
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res += move_integrate(m, axis, 0., end);
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}
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return res;
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}
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// Find a move associated with a given time
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struct move *
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trapq_find_move(struct move *m, double *ptime)
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{
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double move_time = *ptime;
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for (;;) {
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if (unlikely(move_time < 0.)) {
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// Check previous move in list
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m = list_prev_entry(m, node);
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move_time += m->move_t;
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} else if (unlikely(move_time > m->move_t)) {
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// Check next move in list
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move_time -= m->move_t;
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m = list_next_entry(m, node);
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} else {
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*ptime = move_time;
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return m;
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}
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}
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}
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#define NEVER_TIME 9999999999999999.9
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// Allocate a new 'trapq' object
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struct trapq * __visible
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trapq_alloc(void)
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{
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struct trapq *tq = malloc(sizeof(*tq));
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memset(tq, 0, sizeof(*tq));
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list_init(&tq->moves);
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struct move *head_sentinel = move_alloc(), *tail_sentinel = move_alloc();
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tail_sentinel->print_time = tail_sentinel->move_t = NEVER_TIME;
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list_add_head(&head_sentinel->node, &tq->moves);
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list_add_tail(&tail_sentinel->node, &tq->moves);
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return tq;
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}
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// Free memory associated with a 'trapq' object
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void __visible
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trapq_free(struct trapq *tq)
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{
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while (!list_empty(&tq->moves)) {
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struct move *m = list_first_entry(&tq->moves, struct move, node);
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list_del(&m->node);
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free(m);
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}
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free(tq);
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}
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// Update the list sentinels
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void
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trapq_check_sentinels(struct trapq *tq)
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{
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struct move *tail_sentinel = list_last_entry(&tq->moves, struct move, node);
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if (tail_sentinel->print_time)
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// Already up to date
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return;
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struct move *m = list_prev_entry(tail_sentinel, node);
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struct move *head_sentinel = list_first_entry(&tq->moves, struct move,node);
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if (m == head_sentinel) {
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// No moves at all on this list
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tail_sentinel->print_time = NEVER_TIME;
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return;
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}
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tail_sentinel->print_time = m->print_time + m->move_t;
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tail_sentinel->start_pos = move_get_coord(m, m->move_t);
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}
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// Add a move to the trapezoid velocity queue
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void
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trapq_add_move(struct trapq *tq, struct move *m)
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{
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struct move *tail_sentinel = list_last_entry(&tq->moves, struct move, node);
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struct move *prev = list_prev_entry(tail_sentinel, node);
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if (prev->print_time + prev->move_t < m->print_time) {
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// Add a null move to fill time gap
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struct move *null_move = move_alloc();
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null_move->start_pos = m->start_pos;
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null_move->print_time = prev->print_time + prev->move_t;
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null_move->move_t = m->print_time - null_move->print_time;
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list_add_before(&null_move->node, &tail_sentinel->node);
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}
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list_add_before(&m->node, &tail_sentinel->node);
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tail_sentinel->print_time = 0.;
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}
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// Free any moves older than `print_time` from the trapezoid velocity queue
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void __visible
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trapq_free_moves(struct trapq *tq, double print_time)
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{
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struct move *head_sentinel = list_first_entry(&tq->moves, struct move,node);
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struct move *tail_sentinel = list_last_entry(&tq->moves, struct move, node);
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for (;;) {
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struct move *m = list_next_entry(head_sentinel, node);
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if (m == tail_sentinel) {
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tail_sentinel->print_time = NEVER_TIME;
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return;
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}
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if (m->print_time + m->move_t > print_time)
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return;
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list_del(&m->node);
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free(m);
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}
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}
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