786 lines
25 KiB
C
786 lines
25 KiB
C
// Stepper pulse schedule compression
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//
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// Copyright (C) 2016-2021 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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// The goal of this code is to take a series of scheduled stepper
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// pulse times and compress them into a handful of commands that can
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// be efficiently transmitted and executed on a microcontroller (mcu).
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// The mcu accepts step pulse commands that take interval, count, and
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// add parameters such that 'count' pulses occur, with each step event
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// calculating the next step event time using:
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// next_wake_time = last_wake_time + interval; interval += add
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// This code is written in C (instead of python) for processing
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// efficiency - the repetitive integer math is vastly faster in C.
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#include <math.h> // sqrt
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#include <stddef.h> // offsetof
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#include <stdint.h> // uint32_t
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#include <stdio.h> // fprintf
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#include <stdlib.h> // malloc
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#include <string.h> // memset
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#include "compiler.h" // DIV_ROUND_UP
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#include "pyhelper.h" // errorf
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#include "serialqueue.h" // struct queue_message
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#include "stepcompress.h" // stepcompress_alloc
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#define CHECK_LINES 1
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#define QUEUE_START_SIZE 1024
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struct stepcompress {
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// Buffer management
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uint32_t *queue, *queue_end, *queue_pos, *queue_next;
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// Internal tracking
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uint32_t max_error;
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double mcu_time_offset, mcu_freq, last_step_print_time;
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// Message generation
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uint64_t last_step_clock;
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struct list_head msg_queue;
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uint32_t oid;
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int32_t queue_step_msgtag, set_next_step_dir_msgtag;
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int sdir, invert_sdir;
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// Step+dir+step filter
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uint64_t next_step_clock;
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int next_step_dir;
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// History tracking
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int64_t last_position;
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struct list_head history_list;
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};
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struct step_move {
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uint32_t interval;
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uint16_t count;
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int16_t add;
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};
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#define HISTORY_EXPIRE (30.0)
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struct history_steps {
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struct list_node node;
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uint64_t first_clock, last_clock;
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int64_t start_position;
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int step_count, interval, add;
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};
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/****************************************************************
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* Step compression
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****************************************************************/
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static inline int32_t
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idiv_up(int32_t n, int32_t d)
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{
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return (n>=0) ? DIV_ROUND_UP(n,d) : (n/d);
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}
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static inline int32_t
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idiv_down(int32_t n, int32_t d)
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{
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return (n>=0) ? (n/d) : (n - d + 1) / d;
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}
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struct points {
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int32_t minp, maxp;
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};
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// Given a requested step time, return the minimum and maximum
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// acceptable times
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static inline struct points
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minmax_point(struct stepcompress *sc, uint32_t *pos)
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{
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uint32_t lsc = sc->last_step_clock, point = *pos - lsc;
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uint32_t prevpoint = pos > sc->queue_pos ? *(pos-1) - lsc : 0;
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uint32_t max_error = (point - prevpoint) / 2;
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if (max_error > sc->max_error)
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max_error = sc->max_error;
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return (struct points){ point - max_error, point };
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}
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// The maximum add delta between two valid quadratic sequences of the
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// form "add*count*(count-1)/2 + interval*count" is "(6 + 4*sqrt(2)) *
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// maxerror / (count*count)". The "6 + 4*sqrt(2)" is 11.65685, but
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// using 11 works well in practice.
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#define QUADRATIC_DEV 11
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// Find a 'step_move' that covers a series of step times
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static struct step_move
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compress_bisect_add(struct stepcompress *sc)
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{
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uint32_t *qlast = sc->queue_next;
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if (qlast > sc->queue_pos + 65535)
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qlast = sc->queue_pos + 65535;
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struct points point = minmax_point(sc, sc->queue_pos);
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int32_t outer_mininterval = point.minp, outer_maxinterval = point.maxp;
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int32_t add = 0, minadd = -0x8000, maxadd = 0x7fff;
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int32_t bestinterval = 0, bestcount = 1, bestadd = 1, bestreach = INT32_MIN;
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int32_t zerointerval = 0, zerocount = 0;
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for (;;) {
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// Find longest valid sequence with the given 'add'
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struct points nextpoint;
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int32_t nextmininterval = outer_mininterval;
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int32_t nextmaxinterval = outer_maxinterval, interval = nextmaxinterval;
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int32_t nextcount = 1;
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for (;;) {
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nextcount++;
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if (&sc->queue_pos[nextcount-1] >= qlast) {
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int32_t count = nextcount - 1;
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return (struct step_move){ interval, count, add };
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}
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nextpoint = minmax_point(sc, sc->queue_pos + nextcount - 1);
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int32_t nextaddfactor = nextcount*(nextcount-1)/2;
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int32_t c = add*nextaddfactor;
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if (nextmininterval*nextcount < nextpoint.minp - c)
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nextmininterval = idiv_up(nextpoint.minp - c, nextcount);
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if (nextmaxinterval*nextcount > nextpoint.maxp - c)
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nextmaxinterval = idiv_down(nextpoint.maxp - c, nextcount);
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if (nextmininterval > nextmaxinterval)
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break;
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interval = nextmaxinterval;
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}
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// Check if this is the best sequence found so far
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int32_t count = nextcount - 1, addfactor = count*(count-1)/2;
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int32_t reach = add*addfactor + interval*count;
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if (reach > bestreach
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|| (reach == bestreach && interval > bestinterval)) {
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bestinterval = interval;
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bestcount = count;
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bestadd = add;
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bestreach = reach;
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if (!add) {
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zerointerval = interval;
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zerocount = count;
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}
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if (count > 0x200)
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// No 'add' will improve sequence; avoid integer overflow
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break;
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}
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// Check if a greater or lesser add could extend the sequence
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int32_t nextaddfactor = nextcount*(nextcount-1)/2;
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int32_t nextreach = add*nextaddfactor + interval*nextcount;
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if (nextreach < nextpoint.minp) {
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minadd = add + 1;
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outer_maxinterval = nextmaxinterval;
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} else {
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maxadd = add - 1;
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outer_mininterval = nextmininterval;
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}
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// The maximum valid deviation between two quadratic sequences
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// can be calculated and used to further limit the add range.
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if (count > 1) {
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int32_t errdelta = sc->max_error*QUADRATIC_DEV / (count*count);
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if (minadd < add - errdelta)
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minadd = add - errdelta;
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if (maxadd > add + errdelta)
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maxadd = add + errdelta;
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}
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// See if next point would further limit the add range
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int32_t c = outer_maxinterval * nextcount;
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if (minadd*nextaddfactor < nextpoint.minp - c)
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minadd = idiv_up(nextpoint.minp - c, nextaddfactor);
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c = outer_mininterval * nextcount;
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if (maxadd*nextaddfactor > nextpoint.maxp - c)
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maxadd = idiv_down(nextpoint.maxp - c, nextaddfactor);
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// Bisect valid add range and try again with new 'add'
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if (minadd > maxadd)
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break;
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add = maxadd - (maxadd - minadd) / 4;
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}
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if (zerocount + zerocount/16 >= bestcount)
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// Prefer add=0 if it's similar to the best found sequence
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return (struct step_move){ zerointerval, zerocount, 0 };
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return (struct step_move){ bestinterval, bestcount, bestadd };
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}
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/****************************************************************
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* Step compress checking
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****************************************************************/
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// Verify that a given 'step_move' matches the actual step times
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static int
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check_line(struct stepcompress *sc, struct step_move move)
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{
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if (!CHECK_LINES)
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return 0;
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if (!move.count || (!move.interval && !move.add && move.count > 1)
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|| move.interval >= 0x80000000) {
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errorf("stepcompress o=%d i=%d c=%d a=%d: Invalid sequence"
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, sc->oid, move.interval, move.count, move.add);
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return ERROR_RET;
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}
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uint32_t interval = move.interval, p = 0;
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uint16_t i;
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for (i=0; i<move.count; i++) {
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struct points point = minmax_point(sc, sc->queue_pos + i);
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p += interval;
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if (p < point.minp || p > point.maxp) {
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errorf("stepcompress o=%d i=%d c=%d a=%d: Point %d: %d not in %d:%d"
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, sc->oid, move.interval, move.count, move.add
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, i+1, p, point.minp, point.maxp);
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return ERROR_RET;
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}
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if (interval >= 0x80000000) {
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errorf("stepcompress o=%d i=%d c=%d a=%d:"
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" Point %d: interval overflow %d"
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, sc->oid, move.interval, move.count, move.add
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, i+1, interval);
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return ERROR_RET;
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}
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interval += move.add;
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}
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return 0;
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}
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/****************************************************************
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* Step compress interface
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****************************************************************/
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// Allocate a new 'stepcompress' object
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struct stepcompress * __visible
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stepcompress_alloc(uint32_t oid)
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{
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struct stepcompress *sc = malloc(sizeof(*sc));
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memset(sc, 0, sizeof(*sc));
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list_init(&sc->msg_queue);
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list_init(&sc->history_list);
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sc->oid = oid;
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sc->sdir = -1;
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return sc;
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}
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// Fill message id information
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void __visible
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stepcompress_fill(struct stepcompress *sc, uint32_t max_error
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, uint32_t invert_sdir, int32_t queue_step_msgtag
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, int32_t set_next_step_dir_msgtag)
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{
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sc->max_error = max_error;
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sc->invert_sdir = !!invert_sdir;
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sc->queue_step_msgtag = queue_step_msgtag;
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sc->set_next_step_dir_msgtag = set_next_step_dir_msgtag;
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}
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// Helper to free items from the history_list
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static void
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free_history(struct stepcompress *sc, uint64_t end_clock)
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{
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while (!list_empty(&sc->history_list)) {
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struct history_steps *hs = list_last_entry(
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&sc->history_list, struct history_steps, node);
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if (hs->last_clock > end_clock)
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break;
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list_del(&hs->node);
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free(hs);
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}
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}
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// Free memory associated with a 'stepcompress' object
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void __visible
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stepcompress_free(struct stepcompress *sc)
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{
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if (!sc)
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return;
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free(sc->queue);
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message_queue_free(&sc->msg_queue);
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free_history(sc, UINT64_MAX);
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free(sc);
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}
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uint32_t
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stepcompress_get_oid(struct stepcompress *sc)
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{
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return sc->oid;
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}
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int
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stepcompress_get_step_dir(struct stepcompress *sc)
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{
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return sc->next_step_dir;
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}
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// Determine the "print time" of the last_step_clock
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static void
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calc_last_step_print_time(struct stepcompress *sc)
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{
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double lsc = sc->last_step_clock;
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sc->last_step_print_time = sc->mcu_time_offset + (lsc - .5) / sc->mcu_freq;
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if (lsc > sc->mcu_freq * HISTORY_EXPIRE)
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free_history(sc, lsc - sc->mcu_freq * HISTORY_EXPIRE);
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}
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// Set the conversion rate of 'print_time' to mcu clock
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static void
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stepcompress_set_time(struct stepcompress *sc
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, double time_offset, double mcu_freq)
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{
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sc->mcu_time_offset = time_offset;
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sc->mcu_freq = mcu_freq;
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calc_last_step_print_time(sc);
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}
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// Maximium clock delta between messages in the queue
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#define CLOCK_DIFF_MAX (3<<28)
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// Helper to create a queue_step command from a 'struct step_move'
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static void
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add_move(struct stepcompress *sc, uint64_t first_clock, struct step_move *move)
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{
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int32_t addfactor = move->count*(move->count-1)/2;
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uint32_t ticks = move->add*addfactor + move->interval*(move->count-1);
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uint64_t last_clock = first_clock + ticks;
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// Create and queue a queue_step command
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uint32_t msg[5] = {
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sc->queue_step_msgtag, sc->oid, move->interval, move->count, move->add
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};
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struct queue_message *qm = message_alloc_and_encode(msg, 5);
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qm->min_clock = qm->req_clock = sc->last_step_clock;
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if (move->count == 1 && first_clock >= sc->last_step_clock + CLOCK_DIFF_MAX)
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qm->req_clock = first_clock;
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list_add_tail(&qm->node, &sc->msg_queue);
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sc->last_step_clock = last_clock;
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// Create and store move in history tracking
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struct history_steps *hs = malloc(sizeof(*hs));
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hs->first_clock = first_clock;
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hs->last_clock = last_clock;
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hs->start_position = sc->last_position;
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hs->interval = move->interval;
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hs->add = move->add;
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hs->step_count = sc->sdir ? move->count : -move->count;
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sc->last_position += hs->step_count;
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list_add_head(&hs->node, &sc->history_list);
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}
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// Convert previously scheduled steps into commands for the mcu
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static int
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queue_flush(struct stepcompress *sc, uint64_t move_clock)
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{
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if (sc->queue_pos >= sc->queue_next)
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return 0;
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while (sc->last_step_clock < move_clock) {
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struct step_move move = compress_bisect_add(sc);
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int ret = check_line(sc, move);
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if (ret)
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return ret;
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add_move(sc, sc->last_step_clock + move.interval, &move);
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if (sc->queue_pos + move.count >= sc->queue_next) {
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sc->queue_pos = sc->queue_next = sc->queue;
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break;
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}
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sc->queue_pos += move.count;
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}
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calc_last_step_print_time(sc);
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return 0;
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}
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// Generate a queue_step for a step far in the future from the last step
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static int
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stepcompress_flush_far(struct stepcompress *sc, uint64_t abs_step_clock)
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{
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struct step_move move = { abs_step_clock - sc->last_step_clock, 1, 0 };
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add_move(sc, abs_step_clock, &move);
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calc_last_step_print_time(sc);
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return 0;
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}
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// Send the set_next_step_dir command
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static int
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set_next_step_dir(struct stepcompress *sc, int sdir)
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{
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if (sc->sdir == sdir)
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return 0;
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int ret = queue_flush(sc, UINT64_MAX);
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if (ret)
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return ret;
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sc->sdir = sdir;
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uint32_t msg[3] = {
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sc->set_next_step_dir_msgtag, sc->oid, sdir ^ sc->invert_sdir
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};
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struct queue_message *qm = message_alloc_and_encode(msg, 3);
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qm->req_clock = sc->last_step_clock;
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list_add_tail(&qm->node, &sc->msg_queue);
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return 0;
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}
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// Slow path for queue_append() - handle next step far in future
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static int
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queue_append_far(struct stepcompress *sc)
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{
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uint64_t step_clock = sc->next_step_clock;
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sc->next_step_clock = 0;
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int ret = queue_flush(sc, step_clock - CLOCK_DIFF_MAX + 1);
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if (ret)
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return ret;
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if (step_clock >= sc->last_step_clock + CLOCK_DIFF_MAX)
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return stepcompress_flush_far(sc, step_clock);
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*sc->queue_next++ = step_clock;
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return 0;
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}
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// Slow path for queue_append() - expand the internal queue storage
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static int
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queue_append_extend(struct stepcompress *sc)
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{
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if (sc->queue_next - sc->queue_pos > 65535 + 2000) {
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// No point in keeping more than 64K steps in memory
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uint32_t flush = (*(sc->queue_next-65535)
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- (uint32_t)sc->last_step_clock);
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int ret = queue_flush(sc, sc->last_step_clock + flush);
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if (ret)
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return ret;
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}
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if (sc->queue_next >= sc->queue_end) {
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// Make room in the queue
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int in_use = sc->queue_next - sc->queue_pos;
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if (sc->queue_pos > sc->queue) {
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// Shuffle the internal queue to avoid having to allocate more ram
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memmove(sc->queue, sc->queue_pos, in_use * sizeof(*sc->queue));
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} else {
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// Expand the internal queue of step times
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int alloc = sc->queue_end - sc->queue;
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if (!alloc)
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alloc = QUEUE_START_SIZE;
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while (in_use >= alloc)
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alloc *= 2;
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sc->queue = realloc(sc->queue, alloc * sizeof(*sc->queue));
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sc->queue_end = sc->queue + alloc;
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}
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sc->queue_pos = sc->queue;
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sc->queue_next = sc->queue + in_use;
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}
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*sc->queue_next++ = sc->next_step_clock;
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sc->next_step_clock = 0;
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return 0;
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}
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// Add a step time to the queue (flushing the queue if needed)
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static int
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queue_append(struct stepcompress *sc)
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{
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if (unlikely(sc->next_step_dir != sc->sdir)) {
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int ret = set_next_step_dir(sc, sc->next_step_dir);
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if (ret)
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return ret;
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}
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if (unlikely(sc->next_step_clock >= sc->last_step_clock + CLOCK_DIFF_MAX))
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return queue_append_far(sc);
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if (unlikely(sc->queue_next >= sc->queue_end))
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return queue_append_extend(sc);
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*sc->queue_next++ = sc->next_step_clock;
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sc->next_step_clock = 0;
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return 0;
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}
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#define SDS_FILTER_TIME .000750
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// Add next step time
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int
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stepcompress_append(struct stepcompress *sc, int sdir
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, double print_time, double step_time)
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{
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// Calculate step clock
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double offset = print_time - sc->last_step_print_time;
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double rel_sc = (step_time + offset) * sc->mcu_freq;
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uint64_t step_clock = sc->last_step_clock + (uint64_t)rel_sc;
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// Flush previous pending step (if any)
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if (sc->next_step_clock) {
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if (unlikely(sdir != sc->next_step_dir)) {
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double diff = (int64_t)(step_clock - sc->next_step_clock);
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if (diff < SDS_FILTER_TIME * sc->mcu_freq) {
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// Rollback last step to avoid rapid step+dir+step
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sc->next_step_clock = 0;
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sc->next_step_dir = sdir;
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return 0;
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}
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}
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int ret = queue_append(sc);
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if (ret)
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return ret;
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}
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// Store this step as the next pending step
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sc->next_step_clock = step_clock;
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sc->next_step_dir = sdir;
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return 0;
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}
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// Commit next pending step (ie, do not allow a rollback)
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int
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stepcompress_commit(struct stepcompress *sc)
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{
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if (sc->next_step_clock)
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return queue_append(sc);
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return 0;
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}
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// Flush pending steps
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static int
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stepcompress_flush(struct stepcompress *sc, uint64_t move_clock)
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{
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if (sc->next_step_clock && move_clock >= sc->next_step_clock) {
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int ret = queue_append(sc);
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if (ret)
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return ret;
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}
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return queue_flush(sc, move_clock);
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}
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// Reset the internal state of the stepcompress object
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int __visible
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stepcompress_reset(struct stepcompress *sc, uint64_t last_step_clock)
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{
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int ret = stepcompress_flush(sc, UINT64_MAX);
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if (ret)
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return ret;
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sc->last_step_clock = last_step_clock;
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sc->sdir = -1;
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calc_last_step_print_time(sc);
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return 0;
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}
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// Set last_position in the stepcompress object
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int __visible
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stepcompress_set_last_position(struct stepcompress *sc, uint64_t clock
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, int64_t last_position)
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{
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int ret = stepcompress_flush(sc, UINT64_MAX);
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if (ret)
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return ret;
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sc->last_position = last_position;
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// Add a marker to the history list
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struct history_steps *hs = malloc(sizeof(*hs));
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memset(hs, 0, sizeof(*hs));
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hs->first_clock = hs->last_clock = clock;
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hs->start_position = last_position;
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list_add_head(&hs->node, &sc->history_list);
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return 0;
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}
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// Search history of moves to find a past position at a given clock
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int64_t __visible
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stepcompress_find_past_position(struct stepcompress *sc, uint64_t clock)
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{
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int64_t last_position = sc->last_position;
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struct history_steps *hs;
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list_for_each_entry(hs, &sc->history_list, node) {
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if (clock < hs->first_clock) {
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last_position = hs->start_position;
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continue;
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}
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if (clock >= hs->last_clock)
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return hs->start_position + hs->step_count;
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int32_t interval = hs->interval, add = hs->add;
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int32_t ticks = (int32_t)(clock - hs->first_clock) + interval, offset;
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if (!add) {
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offset = ticks / interval;
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} else {
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// Solve for "count" using quadratic formula
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double a = .5 * add, b = interval - .5 * add, c = -ticks;
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offset = (sqrt(b*b - 4*a*c) - b) / (2. * a);
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}
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if (hs->step_count < 0)
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return hs->start_position - offset;
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return hs->start_position + offset;
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}
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return last_position;
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}
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// Queue an mcu command to go out in order with stepper commands
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int __visible
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stepcompress_queue_msg(struct stepcompress *sc, uint32_t *data, int len)
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{
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int ret = stepcompress_flush(sc, UINT64_MAX);
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if (ret)
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return ret;
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struct queue_message *qm = message_alloc_and_encode(data, len);
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qm->req_clock = sc->last_step_clock;
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list_add_tail(&qm->node, &sc->msg_queue);
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return 0;
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}
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// Return history of queue_step commands
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int __visible
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stepcompress_extract_old(struct stepcompress *sc, struct pull_history_steps *p
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, int max, uint64_t start_clock, uint64_t end_clock)
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{
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int res = 0;
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struct history_steps *hs;
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list_for_each_entry(hs, &sc->history_list, node) {
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if (start_clock >= hs->last_clock || res >= max)
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break;
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if (end_clock <= hs->first_clock)
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continue;
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p->first_clock = hs->first_clock;
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p->last_clock = hs->last_clock;
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p->start_position = hs->start_position;
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p->step_count = hs->step_count;
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p->interval = hs->interval;
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p->add = hs->add;
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p++;
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res++;
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}
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return res;
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}
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|
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|
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/****************************************************************
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* Step compress synchronization
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****************************************************************/
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// The steppersync object is used to synchronize the output of mcu
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// step commands. The mcu can only queue a limited number of step
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// commands - this code tracks when items on the mcu step queue become
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// free so that new commands can be transmitted. It also ensures the
|
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// mcu step queue is ordered between steppers so that no stepper
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// starves the other steppers of space in the mcu step queue.
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|
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struct steppersync {
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// Serial port
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struct serialqueue *sq;
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struct command_queue *cq;
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// Storage for associated stepcompress objects
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struct stepcompress **sc_list;
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int sc_num;
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// Storage for list of pending move clocks
|
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uint64_t *move_clocks;
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int num_move_clocks;
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};
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// Allocate a new 'steppersync' object
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struct steppersync * __visible
|
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steppersync_alloc(struct serialqueue *sq, struct stepcompress **sc_list
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, int sc_num, int move_num)
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{
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struct steppersync *ss = malloc(sizeof(*ss));
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memset(ss, 0, sizeof(*ss));
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ss->sq = sq;
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ss->cq = serialqueue_alloc_commandqueue();
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ss->sc_list = malloc(sizeof(*sc_list)*sc_num);
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memcpy(ss->sc_list, sc_list, sizeof(*sc_list)*sc_num);
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ss->sc_num = sc_num;
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ss->move_clocks = malloc(sizeof(*ss->move_clocks)*move_num);
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memset(ss->move_clocks, 0, sizeof(*ss->move_clocks)*move_num);
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ss->num_move_clocks = move_num;
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|
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return ss;
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}
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// Free memory associated with a 'steppersync' object
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void __visible
|
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steppersync_free(struct steppersync *ss)
|
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{
|
|
if (!ss)
|
|
return;
|
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free(ss->sc_list);
|
|
free(ss->move_clocks);
|
|
serialqueue_free_commandqueue(ss->cq);
|
|
free(ss);
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}
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|
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// Set the conversion rate of 'print_time' to mcu clock
|
|
void __visible
|
|
steppersync_set_time(struct steppersync *ss, double time_offset
|
|
, double mcu_freq)
|
|
{
|
|
int i;
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for (i=0; i<ss->sc_num; i++) {
|
|
struct stepcompress *sc = ss->sc_list[i];
|
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stepcompress_set_time(sc, time_offset, mcu_freq);
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}
|
|
}
|
|
|
|
// Implement a binary heap algorithm to track when the next available
|
|
// 'struct move' in the mcu will be available
|
|
static void
|
|
heap_replace(struct steppersync *ss, uint64_t req_clock)
|
|
{
|
|
uint64_t *mc = ss->move_clocks;
|
|
int nmc = ss->num_move_clocks, pos = 0;
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for (;;) {
|
|
int child1_pos = 2*pos+1, child2_pos = 2*pos+2;
|
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uint64_t child2_clock = child2_pos < nmc ? mc[child2_pos] : UINT64_MAX;
|
|
uint64_t child1_clock = child1_pos < nmc ? mc[child1_pos] : UINT64_MAX;
|
|
if (req_clock <= child1_clock && req_clock <= child2_clock) {
|
|
mc[pos] = req_clock;
|
|
break;
|
|
}
|
|
if (child1_clock < child2_clock) {
|
|
mc[pos] = child1_clock;
|
|
pos = child1_pos;
|
|
} else {
|
|
mc[pos] = child2_clock;
|
|
pos = child2_pos;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Find and transmit any scheduled steps prior to the given 'move_clock'
|
|
int __visible
|
|
steppersync_flush(struct steppersync *ss, uint64_t move_clock)
|
|
{
|
|
// Flush each stepcompress to the specified move_clock
|
|
int i;
|
|
for (i=0; i<ss->sc_num; i++) {
|
|
int ret = stepcompress_flush(ss->sc_list[i], move_clock);
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
// Order commands by the reqclock of each pending command
|
|
struct list_head msgs;
|
|
list_init(&msgs);
|
|
for (;;) {
|
|
// Find message with lowest reqclock
|
|
uint64_t req_clock = MAX_CLOCK;
|
|
struct queue_message *qm = NULL;
|
|
for (i=0; i<ss->sc_num; i++) {
|
|
struct stepcompress *sc = ss->sc_list[i];
|
|
if (!list_empty(&sc->msg_queue)) {
|
|
struct queue_message *m = list_first_entry(
|
|
&sc->msg_queue, struct queue_message, node);
|
|
if (m->req_clock < req_clock) {
|
|
qm = m;
|
|
req_clock = m->req_clock;
|
|
}
|
|
}
|
|
}
|
|
if (!qm || (qm->min_clock && req_clock > move_clock))
|
|
break;
|
|
|
|
uint64_t next_avail = ss->move_clocks[0];
|
|
if (qm->min_clock)
|
|
// The qm->min_clock field is overloaded to indicate that
|
|
// the command uses the 'move queue' and to store the time
|
|
// that move queue item becomes available.
|
|
heap_replace(ss, qm->min_clock);
|
|
// Reset the min_clock to its normal meaning (minimum transmit time)
|
|
qm->min_clock = next_avail;
|
|
|
|
// Batch this command
|
|
list_del(&qm->node);
|
|
list_add_tail(&qm->node, &msgs);
|
|
}
|
|
|
|
// Transmit commands
|
|
if (!list_empty(&msgs))
|
|
serialqueue_send_batch(ss->sq, ss->cq, &msgs);
|
|
return 0;
|
|
}
|