1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
|
/**
* Marlin 3D Printer Firmware
* Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
*
* Based on Sprinter and grbl.
* Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*
*/
/*
* MeatPack G-code Compression
*
* Algorithm & Implementation: Scott Mudge - mail@scottmudge.com
* Date: Dec. 2020
*
* Specifically optimized for 3D printing G-Code, this is a zero-cost data compression method
* which packs ~180-190% more data into the same amount of bytes going to the CNC controller.
* As a majority of G-Code can be represented by a restricted alphabet, I performed histogram
* analysis on a wide variety of 3D printing gcode samples, and found ~93% of all gcode could
* be represented by the same 15-character alphabet.
*
* This allowed me to design a system of packing 2 8-bit characters into a single byte, assuming
* they fall within this limited 15-character alphabet. Using a 4-bit lookup table, these 8-bit
* characters can be represented by a 4-bit index.
*
* Combined with some logic to allow commingling of full-width characters outside of this 15-
* character alphabet (at the cost of an extra 8-bits per full-width character), and by stripping
* out unnecessary comments, the end result is gcode which is roughly half the original size.
*
* Why did I do this? I noticed micro-stuttering and other data-bottleneck issues while printing
* objects with high curvature, especially at high speeds. There is also the issue of the limited
* baud rate provided by Prusa's Atmega2560-based boards, over the USB serial connection. So soft-
* ware like OctoPrint would also suffer this same micro-stuttering and poor print quality issue.
*
*/
#pragma once
#include <stdint.h>
/**
* Commands sent to MeatPack to control its behavior.
* They are sent by first sending 2x MeatPack_CommandByte (0xFF) in sequence,
* followed by one of the command bytes below.
* Provided that 0xFF is an exceedingly rare character that is virtually never
* present in G-code naturally, it is safe to assume 2 in sequence should never
* happen naturally, and so it is used as a signal here.
*
* 0xFF *IS* used in "packed" G-code (used to denote that the next 2 characters are
* full-width), however 2 in a row will never occur, as the next 2 bytes will always
* some non-0xFF character.
*/
enum MeatPack_Command : uint8_t {
MPCommand_None = 0,
MPCommand_EnablePacking = 0xFB,
MPCommand_DisablePacking = 0xFA,
MPCommand_ResetAll = 0xF9,
MPCommand_QueryConfig = 0xF8,
MPCommand_EnableNoSpaces = 0xF7,
MPCommand_DisableNoSpaces = 0xF6
};
enum MeatPack_ConfigStateBits : uint8_t {
MPConfig_Bit_Active = 0,
MPConfig_Bit_NoSpaces = 1
};
class MeatPack {
private:
friend class GCodeQueue;
// Utility definitions
static const uint8_t kCommandByte = 0b11111111,
kFirstNotPacked = 0b00001111,
kSecondNotPacked = 0b11110000,
kFirstCharIsLiteral = 0b00000001,
kSecondCharIsLiteral = 0b00000010;
static const uint8_t kSpaceCharIdx = 11;
static const char kSpaceCharReplace = 'E';
static bool cmd_is_next; // A command is pending
static uint8_t state; // Configuration state
static uint8_t second_char; // Buffers a character if dealing with out-of-sequence pairs
static uint8_t cmd_count, // Counter of command bytes received (need 2)
full_char_count, // Counter for full-width characters to be received
char_out_count; // Stores number of characters to be read out.
static uint8_t char_out_buf[2]; // Output buffer for caching up to 2 characters
// Pass in a character rx'd by SD card or serial. Automatically parses command/ctrl sequences,
// and will control state internally.
static void handle_rx_char(const uint8_t c, const serial_index_t serial_ind);
/**
* After passing in rx'd char using above method, call this to get characters out.
* Can return from 0 to 2 characters at once.
* @param out [in] Output pointer for unpacked/processed data.
* @return Number of characters returned. Range from 0 to 2.
*/
static uint8_t get_result_char(char* const __restrict out);
static void reset_state();
static void report_state();
static uint8_t unpacked_char(register const uint8_t in);
static uint8_t unpack_chars(const uint8_t pk, uint8_t* __restrict const chars_out);
static void handle_command(const MeatPack_Command c);
static void handle_output_char(const uint8_t c);
static void handle_rx_char_inner(const uint8_t c);
};
extern MeatPack meatpack;
|
