1
Files
lecture-operating-system-de…/c_os/lib/ScrollbackBuffer.cc
2022-05-17 17:50:19 +02:00

55 lines
2.2 KiB
C++
Executable File

#include "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 + 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 current page
// (The last written line is always before curent_line
// so we need to take the last page if we want the newest lines)
unsigned char rpage = this->pages - page - 1;
// Copy linewise because page may wrap around buffer borders
// Pageheight: 4, Pages: 2 | page = 0 => rpage = 2 - 0 - 1 = 1
// LINE 0 | - line = 0 => wrapline = (5 + 1 * 4 + 0) % 8 = 1
// LINE 1 | - [...]
// LINE 2 | - line = 3 => wrapline = (5 + 1 * 4 + 3) % 8 = 4
// LINE 3 |
// LINE 4 | page = 1 => rpage = 2 - 1 - 1 = 0
// LINE 5 - current_linenumber | - line = 0 => wrapline = (5 + 0 * 4 + 0) % 8 = 5
// LINE 6 | - [...]
// LINE 7 | - line = 3 => wrapline = (5 + 0 * 4 + 3) % 8 = 0
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 + wrapline);
}
}
void ScrollbackBuffer::copy_from_pagebuffer(CGA::cga_page_t* destination) const {
mmem::memcpy<CGA::cga_page_t>(destination, this->pagebuffer);
}
void ScrollbackBuffer::copy_to_pagebuffer(CGA::cga_page_t* source) {
mmem::memcpy<CGA::cga_page_t>(this->pagebuffer, source);
}
void ScrollbackBuffer::clear() {
for (unsigned char page = 0; page < this->pages; ++page) {
mmem::zero<CGA::cga_page_t>(this->buffer + page);
}
mmem::zero<CGA::cga_page_t>(this->pagebuffer);
this->pos = 0;
}