55 lines
1.6 KiB
C
55 lines
1.6 KiB
C
#ifndef _MEMORY_BARRIER_H_
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#define _MEMORY_BARRIER_H_
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#ifdef SIMULATOR
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#define CLI_SEI_BUG_MEMORY_BARRIER()
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#define MEMORY_BARRIER()
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#define ATOMIC_START { \
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uint8_t save_reg = sim_interrupts; \
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cli();
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#define ATOMIC_END MEMORY_BARRIER(); \
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if (save_reg) sei(); \
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}
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#else
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#include <util/atomic.h>
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#include <avr/version.h>
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// Provide a memory barrier to the compiler. This informs
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// the compiler that is should write any cached values that
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// are destined for a global variable and discard any other
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// cached values from global variables.
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//
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// Note that this behavior does apply to all global variables,
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// not just volatile ones. However, cached local variables
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// are not affected as they are not externally visible.
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#define MEMORY_BARRIER() __asm volatile( "" ::: "memory" )
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// There is a bug in the CLI/SEI functions in older versions of
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// avr-libc - they should be defined to include a memory barrier.
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// This macro is used to define the barrier in the code so that
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// it will be easy to remove once the bug has become ancient history.
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// At the moment the bug is included in most of the distributed
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// compilers.
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#if __AVR_LIBC_VERSION__ < 10700UL
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#define CLI_SEI_BUG_MEMORY_BARRIER() MEMORY_BARRIER()
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#else
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#define CLI_SEI_BUG_MEMORY_BARRIER()
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#endif
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#define ATOMIC_START { \
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uint8_t save_reg = SREG; \
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cli(); \
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CLI_SEI_BUG_MEMORY_BARRIER();
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#define ATOMIC_END MEMORY_BARRIER(); \
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SREG = save_reg; \
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}
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#endif
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#endif
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