christoph/lecture-operating-system-development
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implement autoscrolling on screen borders

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This commit is contained in:
churl
2022-05-06 17:30:42 +02:00
parent 12513926d8
commit 38d0ff6e00
5 changed files with 32 additions and 11 deletions
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35
c_os/devices/CGA.cc
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@ -73,11 +73,14 @@ void CGA::show(int x, int y, char character, unsigned char attrib) {
/* Hier muess Code eingefuegt werden */
if (x > 80 || y > 25) {
// Out of bounds
return;
}
char* pos = (char*)(CGA_START + 2 * (x + y * 80)); // cast to char* to make writable
*pos = character;
*(pos + 1) = attrib;
// TODO: screen border check
}
/*****************************************************************************
@ -95,28 +98,44 @@ void CGA::print(char* string, int n, unsigned char attrib) {
/* Hier muess Code eingefuegt werden */
int cursor_x, cursor_y;
int cursor_x, cursor_y; // Don't poll registers every stroke
this->getpos(cursor_x, cursor_y);
for (unsigned short byte = 0; byte < n; ++byte) {
char current = *(string + byte);
if (current == '\n') {
// TODO: Screen bounds
cursor_x = 0;
cursor_y = cursor_y + 1;
if (cursor_y > 24) {
// Bottom of screen reached
this->scrollup();
cursor_y = cursor_y - 1;
}
continue;
} else if (current == '\0') {
// Don't need to run to end if null terminated
break;
}
this->show(cursor_x, cursor_y, current, attrib);
cursor_x = cursor_x + 1;
if (cursor_x > 79) {
// Right of screen reached
cursor_x = 0;
cursor_y = cursor_y + 1;
if (cursor_y > 24) {
// Bottom of screen reached
this->scrollup();
cursor_y = cursor_y - 1;
}
}
}
this->setpos(cursor_x, cursor_y);
// TODO: automatic line breaking, automatic scrolling
}
/*****************************************************************************
@ -175,5 +194,5 @@ unsigned char CGA::attribute(CGA::color bg, CGA::color fg, bool blink) {
return blink << 7 // B0000000
| (bg & 0x7) << 4 // 0HHH0000
| (fg & 0xF); // 0000VVVV
| (fg & 0xF); // 0000VVVV
}