optimized queue unwrapping on arm
diff --git a/aos/linux_code/ipc_lib/queue.cc b/aos/linux_code/ipc_lib/queue.cc
index 67faf5b..81af416 100644
--- a/aos/linux_code/ipc_lib/queue.cc
+++ b/aos/linux_code/ipc_lib/queue.cc
@@ -65,6 +65,17 @@
#endif
};
+inline int RawQueue::index_add1(int index) {
+ // Doing it this way instead of with % is more efficient on ARM.
+ int r = index + 1;
+ assert(index <= data_length_);
+ if (r == data_length_) {
+ return 0;
+ } else {
+ return r;
+ }
+}
+
void RawQueue::DecrementMessageReferenceCount(const void *msg) {
MessageHeader *header = MessageHeader::Get(msg);
__atomic_sub_fetch(&header->ref_count, 1, __ATOMIC_RELAXED);
@@ -287,7 +298,7 @@
int new_end;
while (true) {
- new_end = (data_end_ + 1) % data_length_;
+ new_end = index_add1(data_end_);
// If there is room in the queue right now.
if (new_end != data_start_) break;
if (options & kNonBlock) {
@@ -302,7 +313,7 @@
}
// Avoid leaking the message that we're going to overwrite.
DecrementMessageReferenceCount(data_[data_start_]);
- data_start_ = (data_start_ + 1) % data_length_;
+ data_start_ = index_add1(data_start_);
} else { // kBlock
if (kWriteDebug) {
printf("queue: going to wait for writable_ of %p\n", this);
@@ -409,7 +420,7 @@
}
// This loop pulls each message out of the buffer.
const int pos = data_start_;
- data_start_ = (data_start_ + 1) % data_length_;
+ data_start_ = index_add1(data_start_);
// If this is the last one.
if (data_start_ == data_end_) {
if (kReadDebug) {
@@ -430,7 +441,7 @@
if (options & kPeek) {
IncrementMessageReferenceCount(msg);
} else {
- data_start_ = (data_start_ + 1) % data_length_;
+ data_start_ = index_add1(data_start_);
}
}
ReadCommonEnd();
diff --git a/aos/linux_code/ipc_lib/queue.h b/aos/linux_code/ipc_lib/queue.h
index 255bc63..d4d2609 100644
--- a/aos/linux_code/ipc_lib/queue.h
+++ b/aos/linux_code/ipc_lib/queue.h
@@ -1,6 +1,8 @@
#ifndef AOS_LINUX_CODE_IPC_LIB_QUEUE_H_
#define AOS_LINUX_CODE_IPC_LIB_QUEUE_H_
+#include <assert.h>
+
#include "aos/linux_code/ipc_lib/shared_mem.h"
#include "aos/common/mutex.h"
#include "aos/common/condition.h"
@@ -123,8 +125,11 @@
private:
struct MessageHeader;
+ // Adds 1 to the given index and handles wrapping correctly.
+ int index_add1(int index);
+
bool is_readable() { return data_end_ != data_start_; }
- bool is_writable() { return ((data_end_ + 1) % data_length_) != data_start_; }
+ bool is_writable() { return index_add1(data_end_) != data_start_; }
// These next 4 allow finding the right one.
const char *name_;