File content as of revision 638:c90ae1400bf2:

/*
 * Copyright (c) Nordic Semiconductor ASA
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright notice, this
 *   list of conditions and the following disclaimer in the documentation and/or
 *   other materials provided with the distribution.
 *
 *   3. Neither the name of Nordic Semiconductor ASA nor the names of other
 *   contributors to this software may be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#ifndef _NRF_DELAY_H
#define _NRF_DELAY_H

#include "nrf.h"

/**
 * @brief Function for delaying execution for number of microseconds.
 *
 * @note NRF52 has instruction cache and because of that delay is not precise.
 *
 * @param number_of_ms
 */
/*lint --e{438, 522} "Variable not used" "Function lacks side-effects" */
#if defined ( __CC_ARM   )

static __ASM void __INLINE nrf_delay_us(uint32_t volatile number_of_us)
{
loop
        SUBS    R0, R0, #1
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
#ifdef NRF52
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
        NOP
#endif
        BNE    loop
        BX     LR
}

#elif defined ( __ICCARM__ )

static void __INLINE nrf_delay_us(uint32_t volatile number_of_us)
{
__ASM (
"loop:\n\t"
       " SUBS R0, R0, #1\n\t"
       " NOP\n\t"
       " NOP\n\t"
       " NOP\n\t"
       " NOP\n\t"
       " NOP\n\t"
       " NOP\n\t"
       " NOP\n\t"
       " NOP\n\t"
       " NOP\n\t"
       " NOP\n\t"
       " NOP\n\t"
       " NOP\n\t"
#ifdef NRF52
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
        " NOP\n\t"
#endif
       " BNE.n loop\n\t");
}

#elif defined ( _WIN32 ) || defined ( __unix ) || defined( __APPLE__ )

__STATIC_INLINE void nrf_delay_us(uint32_t volatile number_of_us);

#ifndef CUSTOM_NRF_DELAY_US
__STATIC_INLINE void nrf_delay_us(uint32_t volatile number_of_us)
{}
#endif

#elif defined ( __GNUC__ )

static void __INLINE nrf_delay_us(uint32_t volatile number_of_us) __attribute__((always_inline));
static void __INLINE nrf_delay_us(uint32_t volatile number_of_us)
{
register uint32_t delay __ASM ("r0") = number_of_us;
__ASM volatile (
#ifdef NRF51
        ".syntax unified\n"
#endif
    "1:\n"
    " SUBS %0, %0, #1\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"   
    " NOP\n"  
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
#ifdef NRF52
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
    " NOP\n"
#endif
    " BNE 1b\n"
#ifdef NRF51
    ".syntax divided\n"
#endif
    : "+r" (delay));
}
#endif

void nrf_delay_ms(uint32_t volatile number_of_ms);

#endif