From 92a6ba68f45292a444befae21b2cb90f920cfe6e Mon Sep 17 00:00:00 2001
From: Jaby <fenir50@web.de>
Date: Mon, 19 Dec 2022 21:01:59 +0100
Subject: [PATCH] Introduce FastCircularBuffer

---
 include/PSX/Auxiliary/array_range.hpp     | 17 ++++++++
 include/PSX/Auxiliary/circular_buffer.hpp | 51 +++++++++++++++--------
 2 files changed, 50 insertions(+), 18 deletions(-)
 create mode 100644 include/PSX/Auxiliary/array_range.hpp

diff --git a/include/PSX/Auxiliary/array_range.hpp b/include/PSX/Auxiliary/array_range.hpp
new file mode 100644
index 00000000..19daa078
--- /dev/null
+++ b/include/PSX/Auxiliary/array_range.hpp
@@ -0,0 +1,17 @@
+#ifndef __JABYENGINE_ARRAY_RANGE_HPP__
+#define __JABYENGINE_ARRAY_RANGE_HPP__
+#include "../../stddef.h"
+
+namespace JabyEngine {
+    template<typename T>
+    struct ArrayRange {
+        T*     start = nullptr;
+        size_t size  = 0;
+
+        constexpr ArrayRange() = default;
+        constexpr ArrayRange(T* start, size_t size) : start(start), size(size) {
+        }
+    };
+}
+
+#endif //!__JABYENGINE_ARRAY_RANGE_HPP__
\ No newline at end of file
diff --git a/include/PSX/Auxiliary/circular_buffer.hpp b/include/PSX/Auxiliary/circular_buffer.hpp
index 4dc8ca32..694ce63e 100644
--- a/include/PSX/Auxiliary/circular_buffer.hpp
+++ b/include/PSX/Auxiliary/circular_buffer.hpp
@@ -1,40 +1,30 @@
 #ifndef __JABYENGINE_CIRCULAR_BUFFER_HPP__
 #define __JABYENGINE_CIRCULAR_BUFFER_HPP__
-#include "../../stddef.h"
+#include "array_range.hpp"
 
 namespace JabyEngine {
-    class CircularBuffer {
+    template<typename T, uint32_t ElementCount>
+    class FastCircularBuffer {
         private:
-            typedef uint32_t T;
-
             T*     start_adr = nullptr;
-            size_t end_idx   = 0;
             size_t read_idx  = 0;
             size_t write_idx = 0;
 
-            static size_t increment(size_t cur_idx, size_t end_idx) {
-                static constexpr size_t Step = 1;
-
-                cur_idx += Step;
-                if(cur_idx >= end_idx) {
-                    return (end_idx - cur_idx);
-                }
-
-                return cur_idx;
+            static size_t increment(size_t cur_idx, size_t step) {
+                return ((cur_idx + step) & (ElementCount - 1));
             }
 
         public:
-            CircularBuffer() = default;
+            FastCircularBuffer() = default;
             
             void setup(T* buffer_start_adr, size_t element_count) {
                 this->start_adr = buffer_start_adr;
-                this->end_idx   = element_count;
                 this->read_idx  = 0;
                 this->write_idx = 0;
             }
 
-            T* push() {
-                const auto new_idx = CircularBuffer::increment(this->write_idx, this->end_idx);
+            T* allocate() {
+                const auto new_idx = FastCircularBuffer::increment(this->write_idx, 1);
                 if(new_idx != this->read_idx) {
                     auto* dst = (this->start_adr + this->write_idx);
                     
@@ -45,9 +35,34 @@ namespace JabyEngine {
                 return nullptr;
             }
 
+            const T* pop() {
+                if(this->write_idx != this->read_idx) {
+                    const auto* src = (this->start_adr + this->read_idx);
+                    FastCircularBuffer::drop(1);
+
+                    return src;
+                }
+
+                return nullptr;
+            }
+
+            void drop(size_t elements) {
+                this->read_idx = FastCircularBuffer::increment(this->read_idx, elements);
+            }
+
+            constexpr ArrayRange<T> get_first_continious() const {
+                return {&this->start_adr[this->read_idx], (this->write_idx >= this->read_idx) ? (this->write_idx - this->read_idx) : (ElementCount - this->read_idx)};
+            }
+
+            constexpr ArrayRange<T> get_second_continious() const {
+                return {this->start_adr, (this->write_idx < this->read_idx) ? this->write_idx : 0};
+            }
+
             constexpr bool has_data() const {
                 return (this->read_idx != this->write_idx);
             }
+
+            static_assert(ElementCount == 2 || ElementCount == 4 || ElementCount == 8 || ElementCount == 16 || ElementCount == 32 || ElementCount == 64 || ElementCount == 128 || ElementCount == 256, "ElementCount for FastCircularBuffer must be power of 2");
     };
 }