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Better handling of DELAY_NS and DELAY_US (#10717)

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Co-Authored-By: ejtagle <ejtagle@hotmail.com>
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Scott Lahteine 2018-05-12 04:22:55 -05:00 • committed by GitHub
parent 0aa791d62b
commit 039302bf4c
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14 changed files with 166 additions and 132 deletions
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Marlin/delay.h Normal file
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/**
* Marlin 3D Printer Firmware
* Copyright (C) 2016 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 <http://www.gnu.org/licenses/>.
*
*/
/**
* AVR busy wait delay Cycles routines:
*
* DELAY_CYCLES(count): Delay execution in cycles
* DELAY_NS(count): Delay execution in nanoseconds
* DELAY_US(count): Delay execution in microseconds
*/
#ifndef MARLIN_DELAY_H
#define MARLIN_DELAY_H
#define nop() __asm__ __volatile__("nop;\n\t":::)
FORCE_INLINE static void __delay_4cycles(uint8_t cy) {
__asm__ __volatile__(
L("1")
A("dec %[cnt]")
A("nop")
A("brne 1b")
: [cnt] "+r"(cy) // output: +r means input+output
: // input:
: "cc" // clobbers:
);
}
/* ---------------- Delay in cycles */
FORCE_INLINE static void DELAY_CYCLES(uint16_t x) {
if (__builtin_constant_p(x)) {
#define MAXNOPS 4
if (x <= (MAXNOPS)) {
switch (x) { case 4: nop(); case 3: nop(); case 2: nop(); case 1: nop(); }
}
else {
const uint32_t rem = (x) % (MAXNOPS);
switch (rem) { case 3: nop(); case 2: nop(); case 1: nop(); }
if ((x = (x) / (MAXNOPS)))
__delay_4cycles(x); // if need more then 4 nop loop is more optimal
}
#undef MAXNOPS
}
else
__delay_4cycles(x / 4);
}
#undef nop
/* ---------------- Delay in nanoseconds */
#define DELAY_NS(x) DELAY_CYCLES( (x) * (F_CPU/1000000L) / 1000L )
/* ---------------- Delay in microseconds */
#define DELAY_US(x) DELAY_CYCLES( (x) * (F_CPU/1000000L) )
#endif // MARLIN_DELAY_H