implemented memmove and vga scrolling

4 files changed, 45 insertions, 4 deletions

diff --git a/src/kernel.c b/src/kernel.c
index 60d0dd3..ce6bb1a 100644
--- a/src/kernel.c
+++ b/src/kernel.c
@@ -43,4 +43,9 @@ void entry( void )
 		vga_put_string( &vga, (const char *)msg );
 		vga_put_newline( &vga );
 	}
+	for( int j = 0; j < 50; j++ ) {
+		vga_put_char( &vga, '-' );
+	}
+	vga_put_char( &vga, '>' );
+	vga_put_string( &vga, (const char *)msg );
 }
diff --git a/src/string.c b/src/string.c
index 07042ce..6aa46ef 100644
--- a/src/string.c
+++ b/src/string.c
@@ -9,6 +9,28 @@ void *memset( void *s, int c, size_t n )
 	return s;
 }
 
+void *memmove( void *d, const void *s, size_t n )
+{
+	const char *ss = (const char *)s;
+	char *dd = (char *)d;
+	
+	if( dd == ss ) return d;
+	
+	if( dd <= ss ) {
+		while( n-- ) {
+			*dd++ = *ss++;
+		}
+	} else {
+		dd += n;
+		ss += n;
+		while( n-- ) {
+			*--dd = *--ss;
+		}
+	}
+	
+	return d;
+}
+
 size_t strlen( const char *s )
 {
 	size_t len;
diff --git a/src/string.h b/src/string.h
index b82d1aa..5efd35a 100644
--- a/src/string.h
+++ b/src/string.h
@@ -4,6 +4,7 @@
 #include "sys/types.h"
 
 void *memset( void *s, int c, size_t n );
+void *memmove( void *d, const void *s, size_t n );
 size_t strlen( const char *s );
 
 #endif /* STRING_H */
diff --git a/src/vga.c b/src/vga.c
index 524b6d7..a1230e4 100644
--- a/src/vga.c
+++ b/src/vga.c
@@ -7,6 +7,7 @@
 static bool params_ok( vga_t *vga, const int x, const int y );
 static int calculate_offset( vga_t *vga );
 static uint8_t calculate_color_cell( vga_t *vga );
+static void scroll_screen( vga_t *vga );
 
 void vga_init( vga_t *vga )
 {
@@ -59,6 +60,20 @@ static int calculate_offset( vga_t *vga )
 	return offset;
 }
 
+static void scroll_screen( vga_t *vga )
+{
+	volatile uint8_t *VIDEO_MEMORY = (uint8_t *)0xb8000;
+
+	memmove( (void *)VIDEO_MEMORY, (const void *)VIDEO_MEMORY + 2 * vga->res_x, 2 * ( vga->res_y - 1 ) * vga->res_x );
+
+	for( int i = 2 * ( vga->res_x * ( vga->res_y - 1 ) ); i < 2 * ( vga->res_x * vga->res_y ); i += 2 ) {
+		*(VIDEO_MEMORY+i) = ' ';
+		*(VIDEO_MEMORY+i+1) = calculate_color_cell( vga );
+	}
+	
+	vga->cursor_y = vga->res_y - 1;
+}
+
 static uint8_t calculate_color_cell( vga_t *vga )
 {
 	uint8_t cell;
@@ -101,8 +116,7 @@ void vga_put_char( vga_t *vga, const char c )
 		vga->cursor_x = 0;
 		vga->cursor_y++;
 		if( vga->cursor_y >= vga->res_y ) {
-			// TODO: implement scrolling
-			vga->cursor_y = 0;
+			scroll_screen( vga );
 		}
 	}
 }
@@ -119,8 +133,7 @@ void vga_put_newline( vga_t *vga )
 	vga->cursor_x = 0;
 	vga->cursor_y++;
 	if( vga->cursor_y >= vga->res_y ) {
-		// TODO: implement scrolling
-		vga->cursor_y = 0;
+		scroll_screen( vga );
 	}
 }