89 lines
2.2 KiB
C
89 lines
2.2 KiB
C
#include "vga.h"
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#include "../lib/string.h"
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#include "cpu/memlayout.h"
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#include "port.h"
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static char *const video_memory = (char *)(KERNBASE + 0xb8000);
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enum colors16 : unsigned char {
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black = 0,
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blue,
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green,
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cyan,
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red,
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magenta,
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brown,
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light_gray,
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dark_gray,
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light_blue,
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light_green,
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light_cyan,
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light_red,
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light_magenta,
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yellow,
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white,
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};
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static unsigned char get_color(unsigned char fg, unsigned char bg) {
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return (bg << 4) + fg;
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}
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unsigned vga_get_offset(unsigned col, unsigned row) {
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return row * VGA_COLS + col;
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}
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unsigned vga_get_row_from_offset(unsigned offset) { return offset / VGA_COLS; }
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void vga_set_cursor(unsigned offset) {
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port_byte_out(VGA_CTRL_REGISTER, VGA_OFFSET_HIGH);
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port_byte_out(VGA_DATA_REGISTER, (unsigned char)(offset >> 8));
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port_byte_out(VGA_CTRL_REGISTER, VGA_OFFSET_LOW);
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port_byte_out(VGA_DATA_REGISTER, (unsigned char)(offset & 0xff));
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}
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unsigned vga_get_cursor() {
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port_byte_out(VGA_CTRL_REGISTER, VGA_OFFSET_HIGH);
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unsigned offset = port_byte_in(VGA_DATA_REGISTER) << 8;
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port_byte_out(VGA_CTRL_REGISTER, VGA_OFFSET_LOW);
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offset += port_byte_in(VGA_DATA_REGISTER);
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return offset;
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}
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void vga_set_char(unsigned offset, char c) {
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video_memory[2 * offset] = c;
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video_memory[2 * offset + 1] = get_color(light_gray, black);
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}
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void vga_clear_screen() {
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for (unsigned i = 0; i < VGA_ROWS * VGA_COLS; ++i) {
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vga_set_char(i, ' ');
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}
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vga_set_cursor(0);
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}
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static unsigned scroll() {
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kmemmove(video_memory, video_memory + 2 * VGA_COLS,
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2 * VGA_COLS * (VGA_ROWS - 1));
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for (int col = 0; col < VGA_COLS; col++) {
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vga_set_char(vga_get_offset(col, VGA_ROWS - 1), ' ');
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}
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return vga_get_offset(0, VGA_ROWS - 1);
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}
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void vga_print_string(const char *s) {
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unsigned offset = vga_get_cursor();
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while (*s != 0) {
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if (*s == '\n') {
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offset = vga_get_offset(0, vga_get_row_from_offset(offset) + 1);
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} else {
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vga_set_char(offset, *s);
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offset++;
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}
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s++;
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if (offset >= VGA_COLS * VGA_ROWS) {
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offset = scroll();
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}
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}
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vga_set_cursor(offset);
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}
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