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29 lines
510 B
29 lines
510 B
.var mutex
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.var count
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.main
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.top
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.acquire
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mov $1, %ax
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xchg %ax, mutex # atomic swap of 1 and mutex
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test $0, %ax # if we get 0 back: lock is free!
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je .acquire_done
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yield # if not, yield and try again
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j .acquire
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.acquire_done
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# critical section
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mov count, %ax # get the value at the address
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add $1, %ax # increment it
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mov %ax, count # store it back
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# release lock
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mov $0, mutex
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# see if we're still looping
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sub $1, %bx
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test $0, %bx
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jgt .top
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halt
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