1 files changed, 262 insertions, 0 deletions
diff --git a/src/vgatext.c b/src/vgatext.c
new file mode 100644
index 0000000..cbee587
--- /dev/null
+++ b/src/vgatext.c
@@ -0,0 +1,262 @@
+#include "vgatext.h"
+
+#include <stdbool.h>
+
+#include "string.h"
+#include "stdlib.h"
+#include "kernel.h"
+
+static bool params_ok( vga_text_t *vga_text, const int x, const int y );
+static int calculate_offset( vga_text_t *vga_text, const int x, const int y );
+static uint8_t calculate_color_cell( vga_text_t *vga_text );
+static void scroll_screen( vga_text_t *vga_text );
+
+void vga_text_init( vga_text_t *vga_text )
+{
+	memset( vga_text, 0, sizeof( vga_text_t ) );
+
+	vga_text->res_x = VGA_TEXT_DEFAULT_RES_X;
+	vga_text->res_y = VGA_TEXT_DEFAULT_RES_Y;
+	vga_text->color = VGA_TEXT_COLOR_DARK_GREY;
+	vga_text->background_color = VGA_TEXT_COLOR_BLACK;
+	vga_text->show_mouse_cursor = false;
+	vga_text->mouse_cursor_x = -1;
+	vga_text->mouse_cursor_y = -1;
+
+	// make sure we use the 0x3dx VGA_TEXT ports, is done
+	// in assembly in stage 2 too
+	port8_init( &vga_text->crtc_misc_port, 0x3d2 );
+	port8_write( &vga_text->crtc_misc_port, 1 );
+
+	// set up VGA_TEXT ports
+	port8_init( &vga_text->crtc_index_port, 0x3d4 );
+	port8_init( &vga_text->crtc_data_port, 0x3d5 );
+	
+	vga_text_set_cursor_from_hardware( vga_text );	
+};
+
+void vga_text_clear_screen( vga_text_t *vga_text )
+{
+	volatile uint8_t *VIDEO_MEMORY = (uint8_t *)0xb8000;
+
+	for( int i = 0; i < 2 * ( vga_text->res_x * vga_text->res_y ); i += 2 ) {
+		*(VIDEO_MEMORY+i) = ' ';
+		*(VIDEO_MEMORY+i+1) = calculate_color_cell( vga_text );
+	}
+	
+	vga_text_set_cursor( vga_text, 0, 0 );
+}
+
+void vga_text_set_cursor( vga_text_t *vga_text, const int x, const int y )
+{
+	if( !params_ok( vga_text, x, y ) ) {
+		kernel_panic( "Cursor parameters out of bounds: (%d, %d), resolution is only (%d, %d)",
+			x, y, vga_text->res_x, vga_text->res_y );
+	}
+
+	vga_text->cursor_x = x;
+	vga_text->cursor_y = y;
+	
+	// TODO: have a silent mode where we don't update the cursor
+	vga_text_set_cursor_on_hardware( vga_text );
+}
+
+void vga_text_set_cursor_from_hardware( vga_text_t *vga_text )
+{
+	uint16_t hw_cursor_pos;
+	
+	port8_write( &vga_text->crtc_index_port, 14 );
+	uint8_t data = port8_read( &(vga_text->crtc_data_port ) );
+	hw_cursor_pos = data << 8;
+ 
+	port8_write( &vga_text->crtc_index_port, 15 );
+	data = port8_read( &(vga_text->crtc_data_port ) );
+
+	hw_cursor_pos |= data;
+	
+	vga_text->cursor_x = hw_cursor_pos % vga_text->res_x;
+	vga_text->cursor_y = hw_cursor_pos / vga_text->res_x;
+	
+	// reset to sane values if we get funny values from the VGA_TEXT card
+	if( vga_text->cursor_x < 0 || vga_text->cursor_x > vga_text->res_x ||
+		vga_text->cursor_y < 0 || vga_text->cursor_y > vga_text->res_y ) {
+		vga_text->cursor_x = 0;
+		vga_text->cursor_y = 0;
+	}
+}
+
+void vga_text_set_cursor_on_hardware( vga_text_t *vga_text )
+{
+    uint16_t hw_cursor_pos = vga_text->cursor_x + vga_text->cursor_y * vga_text->res_x;
+
+    port8_write( &vga_text->crtc_index_port, 15 );
+    port8_write( &vga_text->crtc_data_port, hw_cursor_pos & 0xff );
+    port8_write( &vga_text->crtc_index_port, 14 );
+    port8_write( &vga_text->crtc_data_port, hw_cursor_pos >> 8 );
+}
+
+int vga_text_get_cursor_x( vga_text_t *vga_text )
+{
+	return vga_text->cursor_x;
+}
+
+int vga_text_get_cursor_y( vga_text_t *vga_text )
+{
+	return vga_text->cursor_y;
+}
+
+void vga_text_set_color( vga_text_t *vga_text, const vga_text_color_t color )
+{
+	vga_text->color = color;
+}
+
+void vga_text_set_background_color( vga_text_t *vga_text, const vga_text_color_t color )
+{
+	vga_text->background_color = color;
+}
+
+static int calculate_offset( vga_text_t *vga_text, const int x, const int y )
+{
+	int offset = ( vga_text->res_x * y + x ) * 2;
+	
+	return offset;
+}
+
+static void scroll_screen( vga_text_t *vga_text )
+{
+	volatile uint8_t *VIDEO_MEMORY = (uint8_t *)0xb8000;
+	
+	memmove( (void *)VIDEO_MEMORY, (const void *)VIDEO_MEMORY + 2 * vga_text->res_x, 2 * ( vga_text->res_y - 1 ) * vga_text->res_x );
+
+	for( int i = 2 * ( vga_text->res_x * ( vga_text->res_y - 1 ) ); i < 2 * ( vga_text->res_x * vga_text->res_y ); i += 2 ) {
+		*(VIDEO_MEMORY+i) = ' ';
+		*(VIDEO_MEMORY+i+1) = calculate_color_cell( vga_text );
+	}
+	
+	vga_text->cursor_y = vga_text->res_y - 1;
+}
+
+static uint8_t calculate_color_cell( vga_text_t *vga_text )
+{
+	uint8_t cell;
+	
+	cell = ( vga_text->background_color << 4 ) | vga_text->color;
+	
+	return cell;
+}
+
+static bool params_ok( vga_text_t *vga_text, const int x, const int y )
+{
+	if( x > vga_text->res_x || y > vga_text->res_y ) return false;
+
+	return true;
+}
+
+void vga_text_put_char_at( vga_text_t *vga_text, const int x, const int y, const char c )
+{
+	vga_text_set_cursor( vga_text, x, y );
+	vga_text_put_char( vga_text, c );
+}
+
+
+void vga_text_put_string_at( vga_text_t *vga_text, const int x, const int y, const char *s )
+{
+	vga_text_set_cursor( vga_text, x, y );
+	vga_text_put_string( vga_text, s );	
+}
+
+void vga_text_put_char( vga_text_t *vga_text, const char c )
+{		
+	int offset = calculate_offset( vga_text, vga_text->cursor_x, vga_text->cursor_y );
+
+	volatile uint8_t *VIDEO_MEMORY = (uint8_t *)0xb8000;
+	*(VIDEO_MEMORY+offset) = (uint8_t)c;
+	*(VIDEO_MEMORY+offset+1) = calculate_color_cell( vga_text );	
+
+	vga_text->cursor_x++;
+	if( vga_text->cursor_x >= vga_text->res_x ) {
+		vga_text->cursor_x = 0;
+		vga_text->cursor_y++;
+		if( vga_text->cursor_y >= vga_text->res_y ) {
+			scroll_screen( vga_text );
+		}
+	}
+
+	vga_text_set_cursor_on_hardware( vga_text );
+}
+
+void vga_text_put_string( vga_text_t *vga_text, const char *s )
+{
+	for( size_t i = 0; i < strlen( s ); i++ ) {
+		vga_text_put_char( vga_text, s[i] );
+	}
+}
+
+void vga_text_put_newline( vga_text_t *vga_text )
+{
+	vga_text->cursor_x = 0;
+	vga_text->cursor_y++;
+	if( vga_text->cursor_y >= vga_text->res_y ) {
+		scroll_screen( vga_text );
+	}
+
+	vga_text_set_cursor_on_hardware( vga_text );
+}
+
+void vga_text_set_background_color_at( vga_text_t *vga_text, const int x, const int y, vga_text_color_t color )
+{
+	int offset = calculate_offset( vga_text, x, y );
+
+	volatile uint8_t *VIDEO_MEMORY = (uint8_t *)0xb8000;
+	*(VIDEO_MEMORY+offset+1) = ( *(VIDEO_MEMORY+offset+1) & 0x0f ) | ( color << 4 );
+}
+
+vga_text_color_t vga_text_get_background_color_at( vga_text_t *vga_text, const int x, const int y )
+{
+	int offset = calculate_offset( vga_text, x, y );
+
+	volatile uint8_t *VIDEO_MEMORY = (uint8_t *)0xb8000;
+	uint8_t cell = *(VIDEO_MEMORY+offset+1);
+
+	return cell & 0xf0;
+}
+
+void vga_text_inverse_colors_at( vga_text_t *vga_text, const int x, const int y )
+{
+	int offset = calculate_offset( vga_text, x, y );
+
+	volatile uint8_t *VIDEO_MEMORY = (uint8_t *)0xb8000;
+	*(VIDEO_MEMORY+offset+1) = ( ( *(VIDEO_MEMORY+offset+1) & 0x0f ) << 4 )
+		| ( ( *(VIDEO_MEMORY+offset+1) & 0xf0 ) >> 4 );
+}
+
+void vga_text_show_mouse_cursor( vga_text_t *vga_text )
+{
+	if( !vga_text->show_mouse_cursor ) {
+		vga_text->show_mouse_cursor = true;
+		vga_text_inverse_colors_at( vga_text, vga_text->mouse_cursor_x, vga_text->mouse_cursor_y );
+	}
+}
+
+void vga_text_move_mouse_cursor( vga_text_t *vga_text, const int x, const int y )
+{
+	if( vga_text->show_mouse_cursor ) {
+		vga_text_inverse_colors_at( vga_text, vga_text->mouse_cursor_x, vga_text->mouse_cursor_y );
+	}
+	
+	vga_text->mouse_cursor_x = x;
+	vga_text->mouse_cursor_y = y;
+	
+	if( vga_text->show_mouse_cursor ) {
+		vga_text_inverse_colors_at( vga_text, vga_text->mouse_cursor_x, vga_text->mouse_cursor_y );
+	}
+}
+
+void vga_text_hide_mouse_cursor( vga_text_t *vga_text )
+{
+	if( vga_text->show_mouse_cursor ) {
+		vga_text_inverse_colors_at( vga_text, vga_text->mouse_cursor_x, vga_text->mouse_cursor_y );
+		vga_text->show_mouse_cursor = false;
+	}
+}
+