mirror of
https://github.com/grblHAL/core.git
synced 2026-02-06 00:52:35 +08:00
bbd3b69939
Added '$709' setting for second PWM spindle when available - PWM options. Added properties to PWM spindles to allow "overdriving" PWM output when _RPM controls spindle enable signal is enabled with '$9' or '$709'. Optimized Modbus CRC calculation, may fix issue with a compiler generating different code compared to most others. Ref. issue #723.
74 lines
2.1 KiB
C
74 lines
2.1 KiB
C
/*
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crc.c - crc implementations used by grblHAL
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Part of grblHAL
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grblHAL is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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grblHAL is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with grblHAL. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdint.h>
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uint16_t grbl_crc8 (const uint8_t *buf, uint32_t size)
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{
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uint8_t checksum = 0;
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while(size--) {
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checksum = (checksum << 1) | (checksum >> 7);
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checksum += *(buf++);
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}
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return (uint16_t)checksum;
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}
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// Copyright (c) 2006 Christian Walter <wolti@sil.at>
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// Lifted from his FreeModbus Libary
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uint16_t modbus_crc16x (const uint8_t *buf, uint_fast16_t len)
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{
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uint_fast8_t i;
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uint16_t crc = 0xFFFF;
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while(len--) {
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crc ^= (uint16_t)*buf++;; // XOR byte into least sig. byte of crc
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for(i = 8; i != 0; i--) { // Loop over each bit
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if(crc & 0x0001) { // If the LSB is set
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crc >>= 1; // Shift right and XOR 0xA001
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crc ^= 0xA001;
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} else // Else LSB is not set
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crc >>= 1; // Just shift right
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}
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}
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// Note, this number has low and high bytes swapped, so use it accordingly (or swap bytes)
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return crc;
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}
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// Fast CRC16 implementation
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// Original Code: Ashley Roll
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// Optimisations: Scott Dattalo
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// From http://www.ccsinfo.com/forum/viewtopic.php?t=24977
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uint16_t ccitt_crc16 (const uint8_t *buf, uint_fast16_t len)
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{
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uint16_t x, crc = 0;
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while(len--) {
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x = (crc >> 8) ^ *buf++;
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x ^= x >> 4;
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crc = (crc << 8) ^ (x << 12) ^ (x << 5) ^ x;
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}
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return crc;
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}
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