141 lines
2.1 KiB
C
141 lines
2.1 KiB
C
#include <system.h>
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/*
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* Text pointer, background, foreground
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*/
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unsigned short * textmemptr;
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int attrib = 0x0F;
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int csr_x = 0, csr_y = 0;
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/*
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* scroll
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* Scroll the screen
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*/
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void
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scroll() {
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unsigned blank, temp;
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blank = 0x20 | (attrib << 8);
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if (csr_y >= 25) {
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/*
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* Move the current text chunk that makes up the screen
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* back in the buffer by one line.
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*/
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temp = csr_y - 25 + 1;
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memcpy(textmemptr, textmemptr + temp * 80, (25 - temp) * 80 * 2);
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/*
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* Set the chunk of memory that occupies
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* the last line of text to the blank character
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*/
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memsetw(textmemptr + (25 - temp) * 80, blank, 80);
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csr_y = 25 - 1;
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}
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}
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/*
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* move_csr
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* Update the hardware cursor
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*/
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void
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move_csr() {
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unsigned temp;
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temp = csr_y * 80 + csr_x;
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/*
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* Write stuff out.
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*/
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outportb(0x3D4, 14);
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outportb(0x3D5, temp >> 8);
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outportb(0x3D4, 15);
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outportb(0x3D5, temp);
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}
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/*
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* cls
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* Clear the screen
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*/
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void
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cls() {
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unsigned blank;
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int i;
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blank = 0x20 | (attrib << 8);
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for (i = 0; i < 25; ++i) {
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memsetw(textmemptr + i * 80, blank, 80);
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}
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csr_x = 0;
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csr_y = 0;
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move_csr();
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}
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/*
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* putch
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* Puts a character to the screen
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*/
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void
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putch(
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unsigned char c
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) {
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unsigned short *where;
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unsigned att = attrib << 8;
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if (c == 0x08) {
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/* Backspace */
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if (csr_x != 0) csr_x--;
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} else if (c == 0x09) {
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/* Tab */
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csr_x = (csr_x + 8) & ~(8 - 1);
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} else if (c == '\r') {
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/* Carriage return */
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csr_x = 0;
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} else if (c == '\n') {
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/* New line */
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csr_x = 0;
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csr_y++;
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} else if (c >= ' ') {
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where = textmemptr + (csr_y * 80 + csr_x);
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*where = c | att;
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csr_x++;
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}
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if (csr_x >= 80) {
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csr_x = 0;
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csr_y++;
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}
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scroll();
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move_csr();
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}
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/*
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* puts
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* Put string to screen
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*/
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void
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puts(
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unsigned char * text
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){
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int i;
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int len = strlen(text);
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for (i = 0; i < len; ++i) {
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putch(text[i]);
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}
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}
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/*
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* settextcolor
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* Sets the foreground and background color
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*/
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void
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settextcolor(
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unsigned char forecolor,
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unsigned char backcolor
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) {
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attrib = (backcolor << 4) | (forecolor & 0x0F);
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}
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/*
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* init_video
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* Initialize the VGA driver.
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*/
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void init_video() {
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textmemptr = (unsigned short *)0xB8000;
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cls();
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}
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