static bool latching_decr_int_now_zero()

in src/BlocksRuntime/runtime.c [121:135]

• 15 lines of code
• 5 McCabe index (conditional complexity)

static bool latching_decr_int_now_zero(volatile int32_t *where) {
    while (1) {
        int32_t old_value = *where;
        if ((old_value & BLOCK_REFCOUNT_MASK) == BLOCK_REFCOUNT_MASK) {
            return false; // latched high
        }
        if ((old_value & BLOCK_REFCOUNT_MASK) == 0) {
            return false;   // underflow, latch low
        }
        int32_t new_value = old_value - 2;
        if (OSAtomicCompareAndSwapInt(old_value, new_value, where)) {
            return (new_value & BLOCK_REFCOUNT_MASK) == 0;
        }
    }
}