c11_atomic.c
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/*
* Copyright (C) 2015 Eistec AB
*
* This file is subject to the terms and conditions of the GNU Lesser General
* Public License v2.1. See the file LICENSE in the top level directory for more
* details.
*/
/**
* @ingroup core_util
* @{
*
* @file
*
* @brief Implementation of C11 atomic operations if GCC does not provide an
* implementation.
*
* GCC with -mcpu=cortex-m3 and cortex-m4 generate LDREX/STREX instructions
* instead of library calls. There is however currently (2015-05-29) no
* implementation for Cortex-M0, since it lacks the lock-free atomic operations
* found in the M3 and M4 cores.
*
* @note Other CPUs (e.g. msp430, avr) might need this too, but current MSP430
* GCC in Ubuntu/Debian is stuck at version 4.6 which does not provide C11
* language support which makes it difficult to actually make use of this on
* that platform.
*
* @note This implementation completely ignores the memory model parameter
*
* @see https://gcc.gnu.org/wiki/Atomic/GCCMM/LIbrary
*
* @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
*/
#include <stdint.h>
#include "irq.h"
/* GCC documentation refers to the types as I1, I2, I4, I8, I16 */
typedef uint8_t I1;
typedef uint16_t I2;
typedef uint32_t I4;
typedef uint64_t I8;
/* typedef __uint128_t I16; */ /* No 128 bit integer support yet */
/**
* @brief This is a macro that defines a function named __atomic_fetch_<em>opname</em>_<em>n</em>
*
* \param opname operator name that will be used in the function name
* \param op actual C language operator
* \param n width of the data, in bytes
* \param prefixop optional prefix unary operator (use ~ for inverting, NAND, NOR etc)
*/
#define TEMPLATE_ATOMIC_FETCH_OP_N(opname, op, n, prefixop) \
I##n __atomic_fetch_##opname##_##n (volatile void *ptr, I##n val, int memmodel) \
{ \
unsigned int mask = irq_disable(); \
(void)memmodel; \
I##n tmp = *((I##n*)ptr); \
*((I##n*)ptr) = prefixop(tmp op val); \
irq_restore(mask); \
return tmp; \
}
/* Template instantiations below */
TEMPLATE_ATOMIC_FETCH_OP_N( add, +, 1, ) /* __atomic_fetch_add_1 */
TEMPLATE_ATOMIC_FETCH_OP_N( add, +, 2, ) /* __atomic_fetch_add_2 */
TEMPLATE_ATOMIC_FETCH_OP_N( add, +, 4, ) /* __atomic_fetch_add_4 */
TEMPLATE_ATOMIC_FETCH_OP_N( add, +, 8, ) /* __atomic_fetch_add_8 */
TEMPLATE_ATOMIC_FETCH_OP_N( sub, -, 1, ) /* __atomic_fetch_sub_1 */
TEMPLATE_ATOMIC_FETCH_OP_N( sub, -, 2, ) /* __atomic_fetch_sub_2 */
TEMPLATE_ATOMIC_FETCH_OP_N( sub, -, 4, ) /* __atomic_fetch_sub_4 */
TEMPLATE_ATOMIC_FETCH_OP_N( sub, -, 8, ) /* __atomic_fetch_sub_8 */
TEMPLATE_ATOMIC_FETCH_OP_N( and, &, 1, ) /* __atomic_fetch_and_1 */
TEMPLATE_ATOMIC_FETCH_OP_N( and, &, 2, ) /* __atomic_fetch_and_2 */
TEMPLATE_ATOMIC_FETCH_OP_N( and, &, 4, ) /* __atomic_fetch_and_4 */
TEMPLATE_ATOMIC_FETCH_OP_N( and, &, 8, ) /* __atomic_fetch_and_8 */
TEMPLATE_ATOMIC_FETCH_OP_N( or, |, 1, ) /* __atomic_fetch_or_1 */
TEMPLATE_ATOMIC_FETCH_OP_N( or, |, 2, ) /* __atomic_fetch_or_2 */
TEMPLATE_ATOMIC_FETCH_OP_N( or, |, 4, ) /* __atomic_fetch_or_4 */
TEMPLATE_ATOMIC_FETCH_OP_N( or, |, 8, ) /* __atomic_fetch_or_8 */
TEMPLATE_ATOMIC_FETCH_OP_N( xor, ^, 1, ) /* __atomic_fetch_xor_1 */
TEMPLATE_ATOMIC_FETCH_OP_N( xor, ^, 2, ) /* __atomic_fetch_xor_2 */
TEMPLATE_ATOMIC_FETCH_OP_N( xor, ^, 4, ) /* __atomic_fetch_xor_4 */
TEMPLATE_ATOMIC_FETCH_OP_N( xor, ^, 8, ) /* __atomic_fetch_xor_8 */
TEMPLATE_ATOMIC_FETCH_OP_N(nand, &, 1, ~) /* __atomic_fetch_nand_1 */
TEMPLATE_ATOMIC_FETCH_OP_N(nand, &, 2, ~) /* __atomic_fetch_nand_2 */
TEMPLATE_ATOMIC_FETCH_OP_N(nand, &, 4, ~) /* __atomic_fetch_nand_4 */
TEMPLATE_ATOMIC_FETCH_OP_N(nand, &, 8, ~) /* __atomic_fetch_nand_8 */
/** @} */