...

src/vga.c

@@ -0,0 +1,111 @@
+#include "vga.h"
+
+#define ROWS 25
+#define COLUMNS 80
+
+typedef struct
+{
+    uint8_t character;
+    uint8_t color;
+} vga_char;
+
+vga_char* vga_buffer = (vga_char*)0xb8000;
+uint8_t cursor_row = 0;
+uint8_t cursor_col = 0;
+
+void vga_set_char(uint8_t row, uint8_t col, vga_char character)
+{
+    vga_buffer[COLUMNS * row + col] = character;
+}
+
+vga_char vga_char_at(uint8_t row, uint8_t col)
+{
+    return vga_buffer[COLUMNS * row + col];
+}
+
+void vga_reset(void)
+{
+    for (uint8_t row = 0; row < ROWS; row++)
+    {
+        for (uint8_t col = 0; col < COLUMNS; col++)
+        {
+            vga_char character = { .character = ' ', .color = vga_default_color() };
+            vga_set_char(row, col, character);
+        }
+    }
+
+    cursor_row = 0;
+    cursor_col = 0;
+}
+
+void vga_set_cursor_position(uint8_t row, uint8_t col)
+{
+    if (row < ROWS && col < COLUMNS)
+    {
+        cursor_row = row;
+        cursor_col = col;
+    }
+}
+
+void vga_print_char(char character, vga_color_t color)
+{
+    switch (character)
+    {
+    case '\n':
+    {
+        cursor_row += 1;
+        cursor_col = 0;
+        break;
+    }
+    case '\r':
+    {
+        cursor_col = 0;
+        break;
+    }
+    default:
+    {
+        vga_char c = { .character = character, .color = color };
+        vga_set_char(cursor_row, cursor_col, c);
+        cursor_col += 1;
+        break;
+    }
+    }
+
+    if (cursor_col >= COLUMNS)
+    {
+        cursor_col = 0;
+        cursor_row += 1;
+    }
+
+    if (cursor_row >= ROWS)
+    {
+        for (uint8_t row = 1; row < ROWS; row++)
+        {
+            for (uint8_t col = 0; col < COLUMNS; col++)
+            {
+                vga_set_char(row, col, vga_char_at(row - 1, col));
+            }
+        }
+
+        for (uint8_t col = 0; col < COLUMNS; col++)
+        {
+            vga_char character = { .character = ' ', .color = vga_default_color() };
+            vga_set_char(ROWS - 1, col, character);
+        };
+
+        cursor_row = ROWS - 1;
+    }
+}
+
+void vga_print_colored(const char* string, vga_color_t color)
+{
+    for (uint8_t i = 0; string[i] != '\0'; i++)
+    {
+        vga_print_char(string[i], color);
+    }
+}
+
+void vga_print(const char* string)
+{
+    vga_print_colored(string, vga_default_color());
+}