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8d966d98f4
The impact is limited now, but will increase when adding support for more architectures and more bit widths.
89 lines
2.4 KiB
C
89 lines
2.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#ifndef MEMRW_H
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#define MEMRW_H
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/**
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* \file
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*
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* Provides some 32/64-bit memory access functions. These stop the compiler
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* optimizing accesses which need to be ordered and atomic. Mostly used
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* for accessing memory-mapped hardware registers.
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*
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*//*
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* Copyright (C) 2021-2022 Martin Whitaker.
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* Copyright (C) 2024 Lionel Debroux.
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*/
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#include <stdint.h>
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#define __MEMRW_SUFFIX_32BIT "l"
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#define __MEMRW_SUFFIX_64BIT "q"
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#define __MEMRW_READ_INSTRUCTIONS(bitwidth) "mov" __MEMRW_SUFFIX_##bitwidth##BIT " %1, %0"
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#define __MEMRW_WRITE_INSTRUCTIONS(bitwidth) "mov" __MEMRW_SUFFIX_##bitwidth##BIT " %1, %0"
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#define __MEMRW_FLUSH_INSTRUCTIONS(bitwidth) "mov" __MEMRW_SUFFIX_##bitwidth##BIT " %1, %0; mov" __MEMRW_SUFFIX_##bitwidth##BIT " %0, %1"
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#define __MEMRW_READ_FUNC(bitwidth) \
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static inline uint##bitwidth##_t read##bitwidth(const volatile uint##bitwidth##_t *ptr) \
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{ \
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uint##bitwidth##_t val; \
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__asm__ __volatile__( \
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__MEMRW_READ_INSTRUCTIONS(bitwidth) \
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: "=r" (val) \
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: "m" (*ptr) \
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: "memory" \
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); \
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return val; \
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}
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#define __MEMRW_WRITE_FUNC(bitwidth) \
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static inline void write##bitwidth(const volatile uint##bitwidth##_t *ptr, uint##bitwidth##_t val) \
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{ \
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__asm__ __volatile__( \
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__MEMRW_WRITE_INSTRUCTIONS(bitwidth) \
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: \
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: "m" (*ptr), \
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"r" (val) \
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: "memory" \
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); \
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}
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#define __MEMRW_FLUSH_FUNC(bitwidth) \
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static inline void flush##bitwidth(const volatile uint##bitwidth##_t *ptr, uint##bitwidth##_t val) \
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{ \
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__asm__ __volatile__( \
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__MEMRW_FLUSH_INSTRUCTIONS(bitwidth) \
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: \
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: "m" (*ptr), \
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"r" (val) \
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: "memory" \
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); \
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}
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/**
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* Reads and returns the value stored in the 32-bit memory location pointed to by ptr.
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*/
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__MEMRW_READ_FUNC(32)
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/**
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* Reads and returns the value stored in the 64-bit memory location pointed to by ptr.
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*/
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__MEMRW_READ_FUNC(64)
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/**
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* Writes val to the 32-bit memory location pointed to by ptr.
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*/
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__MEMRW_WRITE_FUNC(32)
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/**
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* Writes val to the 64-bit memory location pointed to by ptr.
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*/
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__MEMRW_WRITE_FUNC(64)
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/**
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* Writes val to the 32-bit memory location pointed to by ptr. Only returns when the write is complete.
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*/
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__MEMRW_FLUSH_FUNC(32)
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/**
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* Writes val to the 64-bit memory location pointed to by ptr. Only returns when the write is complete.
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*/
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__MEMRW_FLUSH_FUNC(64)
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#endif // MEMRW_H
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