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;
+}