144 lines
4.5 KiB
C
144 lines
4.5 KiB
C
/*
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* This file is part of the HAL project, inline library above libopencm3.
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*
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* This library is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser 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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*
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* This library 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 Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library. If not, see <http://www.gnu.org/licenses/>.
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*/
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/** @defgroup DELAY_module DELAY module
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*
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* @brief Spin-waiting blocking API
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*
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* @ingroup modules
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*
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* LGPL License Terms @ref lgpl_license
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*/
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#ifndef HAL_DELAY_H_INCLUDED
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#define HAL_DELAY_H_INCLUDED
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#include <libopencm3/cm3/common.h>
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#include <libopencm3/stm32/rcc.h>
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/**@{*/
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/*****************************************************************************/
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/* API definitions */
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/*****************************************************************************/
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/*****************************************************************************/
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/* API Functions */
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/*****************************************************************************/
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BEGIN_DECLS
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/*---------------------------------------------------------------------------*/
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/** @brief Spin-wait delay, spinning specified amount of processor cycles
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*
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* @note this function can be used for delays of max 2500000 cycles.
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* For larger delays, please consider using timers or other waiting techniques.
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*
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* @param[in] cycles Cycles count need to spent in spin-wait
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*/
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static void delay_cycles(const int64_t cycles);
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/*---------------------------------------------------------------------------*/
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/** @brief Spin-wait delay, spinning specified amount of microseconds
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*
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* @note this function can be used for delays max 25 sec @ 168MHz CPU clock, or
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* max 525 sec @ 8MHz CPU clock! For larger delays, please consider using
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* timers or other waiting techniques.
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*
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* @param[in] us Microseconds needed to spin wait.
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* @param[in] cpufreq Current CPU frequency in Hz
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*/
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static void delay_us(uint32_t us);
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/*---------------------------------------------------------------------------*/
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/** @brief Spin-wait delay, spinning specified amount of microseconds
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*
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* @note this function can be used for delays max 25 sec @ 168MHz CPU clock, or
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* max 525 sec @ 8MHz CPU clock! For larger delays, please consider using
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* timers or other waiting techniques.
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*
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* @param[in] ms Milliseconds needed to spin wait.
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* @param[in] cpufreq Current CPU frequency in Hz
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*/
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static void delay_ms(uint32_t ms);
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END_DECLS
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/**@}*/
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/*****************************************************************************/
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/* Architecture dependent implementations */
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/*****************************************************************************/
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static void _delay_3t(uint32_t cycles) __attribute__((naked));
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/* 3 Tcyc per tick, 4Tcyc call/ret, 1Tcyc hidden reg assignment */
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static void _delay_3t(uint32_t cycles)
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{
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asm __volatile__ (
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".syntax unified\n"
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"1: \n"
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" subs %[cyc],#1 \n" /* 1Tck */
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" bne 1b \n" /* 2Tck */
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" bx lr \n"
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".syntax divided\n"
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: /* No output */
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: [cyc] "r" (cycles)
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: /* No memory */
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);
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}
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static inline __attribute__((always_inline)) void delay_cycles(const int64_t cycles)
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{
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if (cycles <= 0)
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return;
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switch (cycles % 3) {
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default:
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case 0: break;
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case 1: asm __volatile__ ("nop"); break;
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case 2: asm __volatile__ ("nop\nnop"); break;
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}
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if (cycles > 3)
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_delay_3t((uint32_t)(cycles / 3));
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else /* same delay as the function call */
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asm __volatile__ ("nop\nnop\nnop\nnop\nnop\nnop\n");
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}
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/* max 25 sec @ 168MHz! */
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/* max 525 sec @ 8MHz! */
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static inline __attribute__((always_inline)) void delay_us(uint32_t us)
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{
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if (us == 0)
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return;
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delay_cycles(us * rcc_ahb_frequency / 1000000 - 6);
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}
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/* max 25 sec @ 168MHz! */
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/* max 525 sec @ 8MHz! */
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static inline __attribute__((always_inline)) void delay_ms(uint32_t ms)
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{
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if (ms == 0)
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return;
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delay_cycles(ms * rcc_ahb_frequency / 1000 - 6);
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}
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#endif /* HAL_DELAY_H_INCLUDED */
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