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Added comments referencing spin-lock lock/unlock read/writes (#1501)

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Mr. Jake 2024-05-20 00:03:32 +02:00 committed by GitHub
parent 7d238ea2cc
commit 3f41d7d2ee
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1 changed files with 2 additions and 2 deletions
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src/rp2_common/hardware_sync/include/hardware/sync.h
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@ -262,7 +262,7 @@ __force_inline static void spin_lock_unsafe_blocking(spin_lock_t *lock) {
// Note we don't do a wfe or anything, because by convention these spin_locks are VERY SHORT LIVED and NEVER BLOCK and run // Note we don't do a wfe or anything, because by convention these spin_locks are VERY SHORT LIVED and NEVER BLOCK and run
// with INTERRUPTS disabled (to ensure that)... therefore nothing on our core could be blocking us, so we just need to wait on another core // with INTERRUPTS disabled (to ensure that)... therefore nothing on our core could be blocking us, so we just need to wait on another core
// anyway which should be finished soon // anyway which should be finished soon
while (__builtin_expect(!*lock, 0)) { while (__builtin_expect(!*lock, 0)) { // read from spinlock register (tries to acquire the lock)
tight_loop_contents(); tight_loop_contents();
} }
__mem_fence_acquire(); __mem_fence_acquire();
@ -275,7 +275,7 @@ __force_inline static void spin_lock_unsafe_blocking(spin_lock_t *lock) {
*/ */
__force_inline static void spin_unlock_unsafe(spin_lock_t *lock) { __force_inline static void spin_unlock_unsafe(spin_lock_t *lock) {
__mem_fence_release(); __mem_fence_release();
*lock = 0; *lock = 0; // write to spinlock register (release lock)
} }
/*! \brief Acquire a spin lock safely /*! \brief Acquire a spin lock safely