initial code commit

.gitignore

@@ -0,0 +1,74 @@
+# This file is used to ignore files which are generated
+# ----------------------------------------------------------------------------
+
+*~
+*.autosave
+*.a
+*.core
+*.moc
+*.o
+*.obj
+*.orig
+*.rej
+*.so
+*.so.*
+*_pch.h.cpp
+*_resource.rc
+*.qm
+.#*
+*.*#
+core
+!core/
+tags
+.DS_Store
+.directory
+*.debug
+Makefile*
+*.prl
+*.app
+moc_*.cpp
+ui_*.h
+qrc_*.cpp
+Thumbs.db
+*.res
+*.rc
+/.qmake.cache
+/.qmake.stash
+
+# qtcreator generated files
+*.pro.user*
+CMakeLists.txt.user*
+
+# xemacs temporary files
+*.flc
+
+# Vim temporary files
+.*.swp
+
+# Visual Studio generated files
+*.ib_pdb_index
+*.idb
+*.ilk
+*.pdb
+*.sln
+*.suo
+*.vcproj
+*vcproj.*.*.user
+*.ncb
+*.sdf
+*.opensdf
+*.vcxproj
+*vcxproj.*
+
+# MinGW generated files
+*.Debug
+*.Release
+
+# Python byte code
+*.pyc
+
+# Binaries
+# --------
+*.dll
+*.exe
+

CMakeLists.txt

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+cmake_minimum_required(VERSION 3.14)
+
+project(ringbuffer LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+add_library(ringbuffer STATIC
+  ringbuffer.cpp
+  ringbuffer.h
+)
+
+target_compile_definitions(ringbuffer PRIVATE RINGBUFFER_LIBRARY)

ringbuffer.cpp

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+#include "ringbuffer.h"
+#include <cstdlib>
+#include <cstring>
+#include <cstddef>
+Ringbuffer::Ringbuffer()
+{
+    Ringbuffer(1024*1024);
+}
+
+Ringbuffer::Ringbuffer(size_t size)
+{
+    this->headptr = (unsigned char*)(malloc(size));
+    this->pSize = size;
+    this->endptr = this->headptr + size;
+    this->readptr = this->headptr;
+    this->writeptr = this->headptr;
+}
+
+Ringbuffer::~Ringbuffer()
+{
+    free(headptr);
+    headptr=endptr=0;
+    readptr=writeptr=0;
+}
+
+size_t Ringbuffer::size() const
+{
+    return pSize;
+}
+
+size_t Ringbuffer::size_free()
+{
+    return pSize - size_used();
+}
+
+size_t Ringbuffer::size_used()
+{
+    if(writeptr>=readptr){
+        return writeptr - readptr;
+    }
+    return (writeptr-headptr) + (endptr - readptr);
+}
+
+size_t Ringbuffer::read(void *buf, size_t bufSize)
+{
+    size_t currentStored = size_used();
+    if(currentStored == 0){
+        return 0;
+    }
+
+    size_t read = currentStored>=bufSize?bufSize:currentStored;
+    if(readptr + read <= endptr){
+        memcpy(buf, readptr, read);
+        readptr = readptr + read;
+    } else {
+        // read with two step
+        size_t first_size = endptr - readptr;
+        size_t second_size = read - first_size;
+        memcpy(buf, readptr, first_size);
+        unsigned char* buf_n = (unsigned char*)(buf) + first_size;
+        memcpy(buf_n, headptr, second_size);
+        readptr = headptr + second_size;
+    }
+
+    return read;
+}
+
+bool Ringbuffer::write(void *buf, size_t bufSize)
+{
+    size_t free = size_free();
+    if(free < bufSize){
+        return false;
+    }
+
+    if(writeptr + bufSize <= endptr){
+        memcpy(writeptr, buf, bufSize);
+        writeptr = writeptr + bufSize;
+    } else {
+        //write with two step
+        size_t first_size = endptr - writeptr;
+        size_t second_size = bufSize - first_size;
+        memcpy(writeptr, buf, first_size);
+        memcpy(headptr, (unsigned char*)buf+first_size, second_size);
+        writeptr = headptr + second_size;
+    }
+    return true;
+}

ringbuffer.h

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+#ifndef RINGBUFFER_H
+#define RINGBUFFER_H
+
+#include <cstddef>
+class Ringbuffer
+{
+public:
+    Ringbuffer();
+    Ringbuffer(size_t size);
+    ~Ringbuffer();
+    size_t size() const;
+    size_t size_free();
+    size_t size_used();
+    size_t read(void *buf, size_t bufSize);
+    bool write(void *buf, size_t bufSize);
+
+private:
+    size_t pSize;
+    unsigned char* headptr;
+    unsigned char* endptr;
+    unsigned char* readptr;
+    unsigned char* writeptr;
+};
+
+#endif // RINGBUFFER_H