From 828d55e708eb31e85cb6ba9580a3bcd89a29e111 Mon Sep 17 00:00:00 2001
From: Thomas Klaehn <thomas.klaehn@perinet.io>
Date: Wed, 30 Oct 2019 11:41:30 +0100
Subject: [PATCH] Ringbuffer

---
 .vscode/launch.json | 29 +++++++++++++++++++++++++++++
 Makefile            | 15 +++------------
 inc/ringbuffer.h    | 24 ++++++++++++++++++++++++
 src/main.cc         | 35 +++++++++++++++--------------------
 src/ringbuffer.cc   | 39 +++++++++++++++++++++++++++++++++++++++
 5 files changed, 110 insertions(+), 32 deletions(-)
 create mode 100644 .vscode/launch.json
 create mode 100644 inc/ringbuffer.h
 create mode 100644 src/ringbuffer.cc

diff --git a/.vscode/launch.json b/.vscode/launch.json
new file mode 100644
index 0000000..c1dcd23
--- /dev/null
+++ b/.vscode/launch.json
@@ -0,0 +1,29 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "g++",
+            "type": "cppdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/bin/test",
+            "args": [],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "externalConsole": false,
+            "MIMode": "gdb",
+            "setupCommands": [
+                {
+                    "description": "Enable pretty-printing for gdb",
+                    "text": "-enable-pretty-printing",
+                    "ignoreFailures": true
+                }
+            ],
+            "preLaunchTask": "all",
+            "miDebuggerPath": "/usr/bin/gdb"
+        }
+    ]
+}
\ No newline at end of file
diff --git a/Makefile b/Makefile
index 3a4ccb1..8ee189c 100644
--- a/Makefile
+++ b/Makefile
@@ -2,23 +2,14 @@ CROSS_COMPILE ?=
 
 TARGET_FILE ?= test
 
-C_FLAGS += -Wall -Werror -DGNU -D__GNU__ -D__GCC__
-C_FLAGS += -Os
-C_FLAGS += -ffunction-sections
-C_FLAGS += -fdata-sections
-C_FLAGS += -std=c18
-C_FLAGS += -pedantic
-C_FLAGS += -pedantic-errors
-C_FLAGS += -ggdb3
-C_FLAGS += -Iinclude
-
-CXXFLAGS += -Os
+CXXFLAGS += -O0
 CXXFLAGS += -ggdb3
 CXXFLAGS += -std=c++17
 CXXFLAGS += -pedantic
 CXXFLAGS += -pedantic-errors
 CXXFLAGS += -ffunction-sections -fdata-sections
 CXXFLAGS += -fno-implicit-inline-templates
+CXXFLAGS += -Iinc
 
 
 LD_LIBS := -lc -lgcc -lpthread
@@ -62,5 +53,5 @@ define makedep
 endef
 
 ifneq ($(MAKECMDGOALS),clean)
--include $($(subst .o,.d,$(OBJS))
+-include $(subst .o,.d,$(OBJS))
 endif
diff --git a/inc/ringbuffer.h b/inc/ringbuffer.h
new file mode 100644
index 0000000..19639cb
--- /dev/null
+++ b/inc/ringbuffer.h
@@ -0,0 +1,24 @@
+#ifndef __INC_RINGBUFFER_H__
+#define __INC_RINGBUFFER_H__
+
+#include <array>
+
+class ringbuffer
+{
+public:
+    ringbuffer();
+
+    int write(char);
+    int read(char&);
+
+private:
+    enum {
+        MAX_BUFFER_SIZE = 2
+    };
+
+    std::array<char, MAX_BUFFER_SIZE> buffer;
+    std::array<char, MAX_BUFFER_SIZE>::iterator head;
+    std::array<char, MAX_BUFFER_SIZE>::iterator tail;
+};
+
+#endif
diff --git a/src/main.cc b/src/main.cc
index 3546f57..d2645ee 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -1,28 +1,23 @@
 #include <iostream>
 
-#include <pthread.h>
+#include "ringbuffer.h"
 
-void *fake_it(void *param)
-{
-    std::cout << "Hello " << __FUNCTION__ << "\r\n";
-    return NULL;
-}
-
-void *poller(void *param)
-{
-    std::cout << "Hello " << __FUNCTION__ << "\r\n";
-    return NULL;
-}
+ringbuffer buf;
 
 int main(void) {
-    pthread_t it_thread, poll_thread;
-
-    pthread_create(&it_thread, NULL, fake_it, NULL);
-    pthread_create(&poll_thread, NULL, poller, NULL);
-    std::cout << "Hello World!!!" << "\r\n";
-
-    pthread_join(it_thread, NULL);
-    pthread_join(poll_thread, NULL);
+    buf.write('a');
+    buf.write('b');
+    buf.write('c');
 
+    char c;
+    if(buf.read(c)) {
+        std::cout << c;
+    }
+    if(buf.read(c)) {
+        std::cout << c;
+    }
+    if(buf.read(c)) {
+        std::cout << c;
+    }
     return 0;
 }
diff --git a/src/ringbuffer.cc b/src/ringbuffer.cc
new file mode 100644
index 0000000..cc74f64
--- /dev/null
+++ b/src/ringbuffer.cc
@@ -0,0 +1,39 @@
+#include "ringbuffer.h"
+
+ringbuffer::ringbuffer()
+{
+    head = buffer.begin();
+    tail = buffer.begin();
+}
+
+int ringbuffer::write(char c)
+{
+    if(head - tail == MAX_BUFFER_SIZE) {
+        return 0;
+    }
+
+    if(head == buffer.end()) {
+        head = buffer.begin();
+    }
+
+    *head = c;
+    head++;
+
+    return 1;
+}
+
+int ringbuffer::read(char& c)
+{
+    if(head - tail == 0) {
+        return 0;
+    }
+
+    if(tail == buffer.end()) {
+        tail = buffer.begin();
+    }
+
+    c = *tail;
+    tail++;
+
+    return 1;
+}