Blank white screen works in VGA graphics

Author: scopeInfinity

.gdbinit

@@ -72,9 +72,9 @@ define view_realmode
 end
 
 define view_kernelmode
-    set $CS_BASE = 0x10000
-    set $DS_BASE = 0x10000
-    set $SS_BASE = 0x10000
+    set $CS_BASE = 0x0C000
+    set $DS_BASE = 0x0C000
+    set $SS_BASE = 0x0C000
     symbol-file build/kernel/core.elf
     clayout
 end

include/fuzzy/drivers/display/vga/graphics.h

@@ -2,5 +2,7 @@
 
 #include <stddef.h>
 
-int graphics_switchto_320x200x256();
+int graphics_set_mode(uint8_t video_mode);
+uint8_t graphics_get_mode();
+
 int graphics_write_320x200x256(int user_ds, uint8_t *__us_buffer);

include/fuzzy/memmgr/layout.h

@@ -1,7 +1,7 @@
 #pragma once
 
 // START_ENSURE_SAME_layout_asm
-#define MEMORY_APP_SIZE         0x20000
+#define MEMORY_APP_SIZE         0x200000
 #define STACKINIT_APP           (MEMORY_APP_SIZE-4)
 #define MEMORY_REALLIBRARY_DATA_ADDRESS  0x70000
 #define MEMORY_REALLIBRARY_DATA_SIZE     0x10000

src/drivers/display/text_mode_vga.c

@@ -88,8 +88,6 @@ void io_low_scroll_screen(char count, unsigned char color,
 void io_low_put_char(char c, unsigned char color) {
     _low_put_char(c,color, location_xy);
     buffer[location_xy]=(((unsigned short)color)<<8)|c;
-    // slows down char printing but good enough for now.
-    io_low_flush();
 }
 
 void io_low_flush() {

src/drivers/display/vga/graphics.c

@@ -6,18 +6,32 @@
 
 #include <stddef.h>
 
-int graphics_switchto_320x200x256() {
-    uint8_t video_mode_flag = 0x13;  // 320x200x256
-    real_mode_client(
+int graphics_set_mode(uint8_t video_mode) {
+    // https://en.wikipedia.org/wiki/INT_10H
+    int eax = real_mode_client(
         0x10, // interrupt number
-        (0x00<<8) | video_mode_flag,
+        (0x00<<8) | video_mode,  // set video mode
         0,  // do not care
         0,  // do not care
         0,  // do not care
         0 // do not care
     );
     return 0;
- }
+}
+
+uint8_t graphics_get_mode() {
+    // https://en.wikipedia.org/wiki/INT_10H
+    int eax = real_mode_client(
+        0x10, // interrupt number
+        (0x0F<<8), // get video mode
+        0,  // do not care
+        0,  // do not care
+        0,  // do not care
+        0 // do not care
+    );
+    // active page ignored
+    return eax&0xFF;
+}
 
 int graphics_write_320x200x256(int user_ds, uint8_t *__us_buffer) {
     const int size = 320*200*1;

src/kernel/syscall/graphics.c

@@ -1,18 +1,38 @@
 #include <fuzzy/kernel/syscall/graphics.h>
 #include <fuzzy/drivers/display/vga/graphics.h>
-
+#include <fuzzy/memmgr/tables/gdt.h>
 #include <graphics.h>
 
+static int _graphics_prev_mode = -1;
+
+
 static int _graphics_init() {
-    // switch to 320x200x256 mode
-    return graphics_switchto_320x200x256();
+    if(_graphics_prev_mode!=-1) {
+        // already in graphics mode
+        return -1;
+    }
+    _graphics_prev_mode = graphics_get_mode();
+    int err = graphics_set_mode(GRAPHIC_MODE_320x200x16);
+    return err;
 }
 
 static int _graphics_close() {
-    return 0;
+    if(_graphics_prev_mode==-1) {
+        // not in graphics mode
+        return -1;
+    }
+    int err = graphics_set_mode(_graphics_prev_mode);
+    // flush text screen
+    flush_screen();
+    _graphics_prev_mode = -1;
+    return err;
 }
 
 static int _graphics_copybuffer(int user_ds, void *_us_buffer) {
+    uint8_t ARR[10][10];
+    for(int i=0;i<10;i++)for(int j=0;j<10;j++) {
+        ARR[i][j] = WHITE;
+    }
     return graphics_write_320x200x256(user_ds, _us_buffer);
 }
 

src/usr/include/graphics.h

@@ -6,7 +6,7 @@
 #define DETECT                  0
 #define GRAPHIC_DRIVER_VGA      1
 
-#define GRAPHIC_MODE_320x200x16 1
+#define GRAPHIC_MODE_320x200x16 0x13
 
 #define  BLACK               0x0
 #define  BLUE                0x1

src/usr/lib/graphics.c

@@ -64,7 +64,7 @@ int getcolor() {
 }
 
 void setbkcolor(int color) {
-    // TODO
+    gstate.bkcolor = color;
 }
 
 int getbkcolor() {