move user stuff to user

c_os/user/ScrollbackBuffer.cc

@@ -0,0 +1,33 @@
+#include "user/ScrollbackBuffer.h"
+
+// NOTE: I added this file
+
+void ScrollbackBuffer::put(CGA::cga_line_t* line) {
+    CGA::cga_line_t* destination = (CGA::cga_line_t*)this->buffer.get() + this->pos;
+    mmem::memcpy<CGA::cga_line_t>(destination, line);
+
+    this->pos = (this->pos + 1) % this->rows;
+}
+
+void ScrollbackBuffer::get(CGA::cga_line_t* destination, unsigned char page) const {
+    if (page < 0 || page >= this->pages) {
+        return;
+    }
+
+    // We reverse the pagenumber so page 0 is always the newest page
+    unsigned char rpage = this->pages - page - 1;
+
+    // Copy linewise because page may wrap around buffer borders
+    unsigned int wrapline;
+    for (unsigned int line = 0; line < (this->rows / this->pages); ++line) {
+        wrapline = (this->pos + rpage * (this->rows / this->pages) + line) % this->rows;
+        mmem::memcpy<CGA::cga_line_t>(destination + line, (CGA::cga_line_t*)this->buffer.get() + wrapline);
+    }
+}
+
+void ScrollbackBuffer::clear() {
+    for (unsigned char page = 0; page < this->pages; ++page) {
+        mmem::zero<CGA::cga_page_t>(this->buffer.get() + page);
+    }
+    this->pos = 0;
+}