christoph/lecture-operating-system-development
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replace hardcoded values with header definitions

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This commit is contained in:
churl
2022-05-08 13:59:50 +02:00
parent 7f3c70f87a
commit a35674b22c
1 changed files with 14 additions and 14 deletions
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28
c_os/devices/CGA.cc
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@ -23,7 +23,7 @@ void CGA::setpos(int x, int y) {
/* Hier muess Code eingefuegt werden */
// NOTE: The cursor addresses positions on screen, not bytes
unsigned short pos = x + y * 80;
unsigned short pos = x + y * COLUMNS;
unsigned char cursor_low = pos & 0xFF;
unsigned char cursor_high = (pos >> 8) & 0xFF;
@ -54,8 +54,8 @@ void CGA::getpos(int& x, int& y) {
unsigned short cursor =
(cursor_low & 0xFF) | ((cursor_high << 8) & 0xFF00);
x = cursor % 80;
y = (int)(cursor / 80);
x = cursor % COLUMNS;
y = (int)(cursor / COLUMNS);
}
/*****************************************************************************
@ -73,12 +73,12 @@ void CGA::show(int x, int y, char character, unsigned char attrib) {
/* Hier muess Code eingefuegt werden */
if (x > 80 || y > 25) {
if (x > COLUMNS || y > ROWS) {
// Out of bounds
return;
}
char* pos = (char*)(CGA_START + 2 * (x + y * 80)); // cast to char* to make writable
char* pos = (char*)(CGA_START + 2 * (x + y * COLUMNS)); // cast to char* to make writable
*pos = character;
*(pos + 1) = attrib;
}
@ -107,7 +107,7 @@ void CGA::print(char* string, int n, unsigned char attrib) {
cursor_x = 0;
cursor_y = cursor_y + 1;
if (cursor_y > 24) {
if (cursor_y >= ROWS) {
// Bottom of screen reached
this->scrollup();
cursor_y = cursor_y - 1;
@ -122,12 +122,12 @@ void CGA::print(char* string, int n, unsigned char attrib) {
this->show(cursor_x, cursor_y, current, attrib);
cursor_x = cursor_x + 1;
if (cursor_x > 79) {
if (cursor_x >= COLUMNS) {
// Right of screen reached
cursor_x = 0;
cursor_y = cursor_y + 1;
if (cursor_y > 24) {
if (cursor_y >= ROWS) {
// Bottom of screen reached
this->scrollup();
cursor_y = cursor_y - 1;
@ -150,12 +150,12 @@ void CGA::scrollup() {
/* Hier muess Code eingefuegt werden */
// Move up
for (unsigned short byte = 2 * 80 * 1; byte < 2 * 80 * 25; ++byte) {
*((char*)(CGA_START + byte - 2 * 80 * 1)) = *(CGA_START + byte);
for (unsigned short byte = 2 * COLUMNS * 1; byte < 2 * COLUMNS * ROWS; ++byte) {
*((char*)(CGA_START + byte - 2 * COLUMNS * 1)) = *(CGA_START + byte);
}
// Clear last line
for (unsigned short byte = 2 * 80 * 24; byte < 2 * 80 * 25; ++byte) {
for (unsigned short byte = 2 * COLUMNS * (ROWS - 1); byte < 2 * COLUMNS * ROWS; ++byte) {
*((char*)(CGA_START + byte)) = '\0';
}
}
@ -169,7 +169,7 @@ void CGA::clear() {
/* Hier muess Code eingefuegt werden */
for (unsigned short byte = 2 * 80 * 0; byte < 2 * 80 * 25; ++byte) {
for (unsigned short byte = 2 * COLUMNS * 0; byte < 2 * COLUMNS * ROWS; ++byte) {
*((char*)(CGA_START + byte)) = '\0';
}
@ -193,6 +193,6 @@ unsigned char CGA::attribute(CGA::color bg, CGA::color fg, bool blink) {
/* Hier muess Code eingefuegt werden */
return blink << 7 // B0000000
| (bg & 0x7) << 4 // 0HHH0000
| (fg & 0xF); // 0000VVVV
| (bg & 0x7) << 4 // 0HHH0000 (Hintergrund)
| (fg & 0xF); // 0000VVVV (Vordergrund)
}