Added display buffer per application

Author: scopeInfinity

src/drivers/display/text_mode.h

@@ -13,4 +13,6 @@ void io_low_scroll_screen(char count, unsigned char color,
                           int x1, int y1,
                           int x2, int y2);
 
-void io_low_put_char(char c, unsigned char color);
+void io_low_put_char(char c, unsigned char color);
+
+void io_low_flush();

src/drivers/display/text_mode_bios.c

@@ -52,5 +52,9 @@ void io_low_scroll_screen(char count, unsigned char color,
 }
 
 void io_low_put_char(char c, unsigned char color) {
-    _low_put_chars(c, 1, color);
+  _low_put_chars(c, 1, color);
+}
+
+void io_low_flush() {
+  // Not implemented, as it's not required.
 }

src/drivers/display/text_mode_vga.asm

@@ -2,6 +2,7 @@
 
 global _low_put_char
 global _low_vga_copy_step
+global _low_flush
 
 [SECTION .text]
     _low_put_char:
@@ -47,4 +48,23 @@ global _low_vga_copy_step
         pop ds
         mov esp, ebp
         pop ebp
+        ret
+
+    _low_flush:
+        push ebp
+        mov ebp, esp
+        push es
+        mov eax, 0x20
+        mov es, eax                 ; Absolute memory address
+
+        mov esi,[ebp + 0x8]    ; (buffer)
+        mov cx, [ebp + 0xc]    ; (count)
+        mov edi, 0xb8000
+
+        cld
+        rep movsw
+
+        pop es
+        mov esp, ebp
+        pop ebp
         ret

src/drivers/display/text_mode_vga.c

@@ -4,10 +4,13 @@ extern void _low_put_char(char c, unsigned char color, unsigned int xy);
 
 extern void _low_vga_copy_step(unsigned int xy1, unsigned int xy2, unsigned int count);
 
+extern _low_flush(unsigned short *buffer, int count);
+
 static int location_xy = 0;
 
 int IO_CURRENT_X = 0;
 int IO_CURRENT_Y = 0;
+unsigned short buffer[TEXT_WINDOW_HEIGHT*TEXT_WINDOW_WIDTH] = {0};
 
 int get_display_text_x() {
     return IO_CURRENT_X;
@@ -38,40 +41,40 @@ void io_low_scroll_screen(char count, unsigned char color,
                           int x2, int y2) {
     if (count == 0) {
         for (int r = y1; r <= y2; ++r) {
-            int index = r*TEXT_WINDOW_WIDTH;
-            for (int c = x1; c <= x2; ++c, index++) {
-                _low_put_char(' ', color, index);
+            int d_index = r*TEXT_WINDOW_WIDTH+x1;
+            for (int c = x1; c <= x2; ++c) {
+                buffer[d_index++]=(color<<8)|' ';
             }
         }
     } else if (count > 0) {
         // Not yet tested.
         int width = x2-x1+1;
-        for (int r1=y1,r2 = y1+count; r2 <= y2; r1++,r2++) {
-            _low_vga_copy_step(
-                r2*TEXT_WINDOW_WIDTH + x1,
-                r1*TEXT_WINDOW_WIDTH + x1,
-                width
-                );
-            io_low_scroll_screen(0,color,
-                x1, y2-count,
-                x2, y2);
+        for (int r_dest=y1,r_src = y1+count; r_src <= y2; r_src++,r_dest++) {
+            int s_index = r_src*TEXT_WINDOW_WIDTH+x1;
+            int d_index = r_dest*TEXT_WINDOW_WIDTH+x1;
+            for (int j = x1; j <= x2; ++j) {
+                buffer[d_index++]=buffer[s_index++];
+            }
         }
     } else {
         // Not yet tested.
         int width = x2-x1+1;
-        for (int r1=y2,r2 = y2+count; r2 >= y1; r1--,r2--) {
-            _low_vga_copy_step(
-                r2*TEXT_WINDOW_WIDTH + x1,
-                r1*TEXT_WINDOW_WIDTH + x1,
-                width
-                );
-            io_low_scroll_screen(0,color,
-                x1, y1,
-                x2, y1+count);
+        for (int r_dest=y2,r_src = y2+count; r_src >= y1; r_src--,r_dest--) {
+            int s_index = r_src*TEXT_WINDOW_WIDTH+x1;
+            int d_index = r_dest*TEXT_WINDOW_WIDTH+x1;
+            for (int j = x1; j <= x2; ++j) {
+                buffer[d_index++]=buffer[s_index++];
+            }
         }
     }
+    io_low_flush();
 }
 
 void io_low_put_char(char c, unsigned char color) {
     _low_put_char(c,color, location_xy);
+    buffer[location_xy]=(color<<8)|c;
+}
+
+void io_low_flush() {
+    _low_flush(buffer, sizeof(buffer)/2);
 }

src/kernel/process.c

@@ -1,5 +1,6 @@
 #pragma once
 #include <lib/utils/logging.h>
+#include <lib/utils/output.h>
 
 #include "memmgr/tables/gdt.c"
 
@@ -81,5 +82,6 @@ int process_exec(int sector_index, int sector_count) {
         *(int*)relative_address);
     int exit_code = call_main(0, 0);
     process_free_id(id);
+    io_low_flush();
     return exit_code;
 }

src/lib/utils/output.c

@@ -3,6 +3,10 @@
 #include <lib/utils/output.h>
 #include <drivers/display/text_mode.h>
 
+void flush_screen() {
+    io_low_flush();
+}
+
 void move_x(unsigned char x) {
     set_display_text_x(x);
 }

src/lib/utils/output.h

@@ -7,6 +7,7 @@ extern "C" {
 #include <lib/utils/color.h>
 #include <drivers/display/text_mode.h>
 
+void flush_screen();
 void move_x(unsigned char x);
 void move_y(unsigned char y);
 void move_xy(unsigned char x, unsigned char y);