《操作系统》的实验代码。
 
 
 
 
 

29 lines
496 B

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