implement a scrollback buffer

c_os/devices/BufferedCGA.cc

@@ -0,0 +1,75 @@
+#include "BufferedCGA.h"
+
+// Can't initialize in constructor as memory management already needs working CGA for output
+// NOTE: This has to be called when memorymanagement is active
+void BufferedCGA::init() {
+    this->scrollback_buffer = new ScrollbackBuffer(COLUMNS, ROWS, 5);
+    this->initialized = true;
+
+    this->print("\nInitialized scrollback buffer with 5 pages\n\n", 45);
+}
+
+void BufferedCGA::displaypage() {
+    if (this->current_page == 0) {
+        // Use pagebuffer
+        this->scrollback_buffer->copy_page_from_pagebuffer((cga_page_t*)CGA_START);
+    } else {
+        // Use scrollback
+        this->scrollback_buffer->copy_page_from_buffer((cga_line_t*)CGA_START, this->current_page - 1);
+    }
+}
+
+void BufferedCGA::print(char* string, int n, unsigned char attrib) {
+    if (this->current_page != 0) {
+        // Display newest content from buffer when new prints happen
+
+        this->current_page = 0;
+        this->displaypage();
+    }
+
+    CGA::print(string, n, attrib);
+}
+
+void BufferedCGA::scrollup() {
+    if (this->initialized) {
+        this->scrollback_buffer->line_to_buffer((cga_line_t*)CGA_START);
+    } else {
+        this->print("ScrollbackBuffer not initialized\n\n", 34);
+    }
+
+    CGA::scrollup();
+}
+
+void BufferedCGA::clear() {
+    CGA::clear();
+    this->current_page = 0;
+
+    if (this->initialized) {
+        this->scrollback_buffer->clear();
+    } else {
+        this->print("ScrollbackBuffer not initialized\n\n", 34);
+    }
+}
+
+unsigned int BufferedCGA::scroll_page_backward() {
+    // If this is the first scrollback we have to save the current screen content
+    if (this->current_page == 0) {
+        this->scrollback_buffer->copy_page_to_pagebuffer((cga_page_t*)CGA_START);
+    }
+
+    // current_page can be equal to scrollback_buffer->pages
+    // as we have a separate pagebuffer for the current screen content
+    if (this->current_page < this->scrollback_buffer->pages) {
+        this->current_page = this->current_page + 1;
+    }
+    this->displaypage();
+    return this->current_page;
+}
+
+unsigned int BufferedCGA::scroll_page_forward() {
+    if (this->current_page > 0) {
+        this->current_page = this->current_page - 1;
+    }
+    this->displaypage();
+    return this->current_page;
+}

c_os/devices/BufferedCGA.h

@@ -0,0 +1,32 @@
+#ifndef __BUFFEREDCGA_INCLUDE_H_
+#define __BUFFEREDCGA_INCLUDE_H_
+
+#include "devices/CGA.h"
+#include "devices/Keyboard.h"
+#include "lib/ScrollbackBuffer.h"
+
+// NOTE: I added this file
+
+class BufferedCGA : public CGA {
+private:
+    ScrollbackBuffer* scrollback_buffer;
+    bool initialized;  // Don't do ScrollbackBuffer actions if not initialized
+
+    BufferedCGA(const CGA& copy);
+
+    void displaypage();  // Write the current_page to CGA memory
+
+public:
+    BufferedCGA() : CGA(), initialized(false), current_page(0) {};
+
+    void init();                          // Scrollback needs to be initialized after memorymanagement
+    unsigned char current_page;           // The page that is displayed
+    unsigned int scroll_page_backward();  // Scroll up the page history
+    unsigned int scroll_page_forward();   // Scroll down the page history (to the current page)
+
+    void print(char* string, int n, unsigned char attrib = STD_ATTR) override;
+    void scrollup() override;
+    void clear() override;
+};
+
+#endif

c_os/devices/CGA_Stream.h

@@ -15,7 +15,7 @@
 #ifndef __CGA_Stream_include__
 #define __CGA_Stream_include__
 
-#include "devices/CGA.h"
+#include "devices/BufferedCGA.h"
 #include "lib/OutStream.h"
 
 // NOTE: I added this
@@ -32,7 +32,8 @@ public:
     CGA::color bg;
 };
 
-class CGA_Stream : public OutStream, public CGA {
+// NOTE: I added this (changed this) to use BufferedCGA
+class CGA_Stream : public OutStream, public BufferedCGA {
 private:
     CGA_Stream(CGA_Stream& copy);  // Verhindere Kopieren
 
@@ -41,7 +42,7 @@ public:
     CGA::color color_bg;
     bool blink;
 
-    CGA_Stream() : OutStream(), CGA() {
+    CGA_Stream() : OutStream(), BufferedCGA() {
         color_fg = CGA::LIGHT_GREY;
         color_bg = CGA::BLACK;
         blink = false;