Begin implementing a link between the GUI shell and the kernel.

Add a system call that allows the GUI shell to register a callback with the OS.
The OS can call this function to send messages to the GUI on behalf of the applications.

Author: tthomps

MyOS_1/Build_Number.h

@@ -3,4 +3,4 @@
 // Define a build number. This number will be incremented by a simple console program called by a post-build event
 // It's put here in its own file to keep the other program from messing up the source
 #define \
-BUILD_NUMBER 5654
+BUILD_NUMBER 5704

MyOS_1/GUI_Kernel.c

@@ -0,0 +1,21 @@
+#include "GUI_Kernel.h"
+#include "GUI_Messages.h"
+#include "Tasks/Context.h"
+
+GUI_CALLBACK guiCallback = NULL;
+
+void GUI_CallbackAdded()
+{
+    // Send a new window message to the GUI shell for each running application
+    for (int i = 0; i < MAX_TASKS; ++i)
+    {
+        if (!tasks[i].inUse)
+            continue;
+
+        // Construct the message data
+        GUI_NEW_CONSOLE_APP_DATA data;
+        data.appName = tasks[i].imageName;
+
+        (*guiCallback)(tasks[i].PID, GUI_MSG_NEW_CONSOLE_APP, &data);
+    }
+}

MyOS_1/GUI_Kernel.h

@@ -0,0 +1,11 @@
+#pragma once
+#include <stdint.h>
+
+// definitions for interfacing between User apps <> kernel <> GUI shell
+
+typedef void(*GUI_CALLBACK)(uint32_t PID, uint32_t messageType, void *pData);
+
+extern GUI_CALLBACK guiCallback;
+
+// Called immediately after a callback has been registered, to transition running apps into windowed consoles
+void GUI_CallbackAdded();

MyOS_1/GUI_Messages.h

@@ -0,0 +1,17 @@
+#pragma once
+#include <stdint.h>
+
+// MESSAGES
+#define GUI_MSG_NEW_CONSOLE_APP 0x1000
+// END OF MESSAGES
+
+// DATA TYPES USED BY MESSAGES
+
+// Data type used by GUI_MSG_NEW_CONSOLE_APP messages
+typedef struct GUI_NEW_CONSOLE_APP_DATA
+{
+    const char *appName;
+
+    // TODO: We may as well send the terminal contents over in the same message
+} GUI_NEW_CONSOLE_APP_DATA;
+// END OF DATA TYPES

MyOS_1/Interrupts/IDT.c

@@ -94,6 +94,9 @@ void IDT_Init(void)
     // Set handler for hiding shell display elements
     Set_IDT_Entry((unsigned long)hide_shell_display_interrupt_handler, SYSCALL_HIDE_SHELL_DISPLAY);
 
+    // Set handler for the GUI telling the kernel how to send the GUI messages
+    Set_IDT_Entry((unsigned long)gui_register_callback_interrupt_handler, SYSCALL_REGISTER_GUI_CALLBACK);
+
     /* fill the IDT descriptor */
     IDT_ptr.base = (uint32_t)IDT;
     IDT_ptr.size = (sizeof(IDT_ENTRY) * 256);

MyOS_1/Interrupts/Interrupts.c

@@ -14,6 +14,7 @@
 #include "../myos_io.h"
 #include "../Tasks/Context.h"
 #include "../Drivers/PS2_Mouse.h"
+#include "../GUI_Kernel.h"
 
 unsigned long interrupts_fired;
 
@@ -457,6 +458,40 @@ void _declspec(naked) graphics_blit_interrupt_handler(int eflags, int cs, const
     }
 }
 
+void _declspec(naked) gui_register_callback_interrupt_handler(int eflags, int cs, GUI_CALLBACK callbackFunc)
+{
+    // supress warning about unused parameters
+    (void)eflags, (void)cs, (void)callbackFunc;
+
+    _asm
+    {
+        // prologue
+        push ebp
+        mov ebp, esp
+        pushad
+    }
+
+    ++interrupts_fired;
+
+    if (debugLevel)
+        terminal_writestring("GUI register callback interrupt handler fired.\n");
+
+    // TODO IMPORTANT The GUI application should be mapped to kernel space
+
+    guiCallback = callbackFunc;
+
+    GUI_CallbackAdded();
+
+    _asm
+    {
+        popad
+        // epilogue
+        pop ebp
+
+        iretd
+    }
+}
+
 void _declspec(naked) hide_shell_display_interrupt_handler(int eflags, int cs)
 {
     // supress warning about unused parameters

MyOS_1/Interrupts/Interrupts.h

@@ -7,6 +7,7 @@
 #include "../Graphics/Display_HAL.h"
 #include "../myos_io.h"
 #include "../Drivers/mouse.h"
+#include "../GUI_Kernel.h"
 
 #define HARDWARE_INTERRUPTS_BASE     0x20
 
@@ -38,6 +39,8 @@ void gpf_exception_handler(void);
 
 void graphics_blit_interrupt_handler(int eflags, int cs, const SDL_Rect *sourceRect, PIXEL_32BIT *image);
 
+void gui_register_callback_interrupt_handler(int eflags, int cs, GUI_CALLBACK callbackFunc);
+
 void hide_shell_display_interrupt_handler(int eflags, int cs);
 
 void Interrupts_Add_Shared_Handler(bool (*sharedHandlerAddress)(void), uint8_t irq);

MyOS_1/Interrupts/System_Calls.c

@@ -76,6 +76,18 @@ size_t SystemCallFRead(void * bufPtr, size_t elemSize, size_t count, FILE * stre
     return retVal;
 }
 
+void SystemCallRegisterGuiCallback(GUI_CALLBACK guiCallback)
+{
+    const int pointerSize = sizeof(GUI_CALLBACK);
+
+    __asm
+    {
+        push [guiCallback]                  // push argument onto stack
+        int SYSCALL_REGISTER_GUI_CALLBACK   // call gui_register_callback_interrupt_handler(guiCallback)
+        add esp, pointerSize                // restore value of stack pointer
+    }
+}
+
 int SystemCallFSeek(FILE * stream, long int off, int origin)
 {
     int retVal;

MyOS_1/Interrupts/System_Calls.h

@@ -10,6 +10,7 @@ extern "C" {
 #include "../Libs/SDL/include/SDL_rect.h"
 #include "../myos_io.h"
 #include "../Drivers/mouse.h"
+#include "../GUI_Kernel.h"
 
 #define SYSCALL_PRINT               255
 #define SYSCALL_PRINTF              254
@@ -28,6 +29,7 @@ extern "C" {
 #define SYSCALL_DISPATCH_NEW_TASK   241
 #define SYSCALL_GET_MOUSE_STATE     240
 #define SYSCALL_HIDE_SHELL_DISPLAY  239
+#define SYSCALL_REGISTER_GUI_CALLBACK   238
 
 void SystemCallExit();
 #define exit SystemCallExit
@@ -67,6 +69,9 @@ void SystemCallPrint(char *str);
 bool SystemCallReadFromKeyboard(uint16_t *key);
 #define readFromKeyboard SystemCallReadFromKeyboard
 
+void SystemCallRegisterGuiCallback(GUI_CALLBACK guiCallback);
+#define registerGuiCallback SystemCallRegisterGuiCallback
+
 #define printf SystemCallPrintf
 int __cdecl SystemCallPrintf(const char* format, ...);
 

MyOS_1/MyOS_1.vcxproj

@@ -299,6 +299,7 @@
     <ClCompile Include="Graphics\font.c" />
     <ClCompile Include="Graphics\Graphical_Terminal.c" />
     <ClCompile Include="Graphics\picofont.c" />
+    <ClCompile Include="GUI_Kernel.c" />
     <ClCompile Include="Interrupts\IDT.c" />
     <ClCompile Include="Interrupts\Interrupts.c" />
     <ClCompile Include="Interrupts\PIC.c" />
@@ -350,6 +351,8 @@
     <ClInclude Include="Graphics\Display_HAL.h" />
     <ClInclude Include="Graphics\Graphical_Terminal.h" />
     <ClInclude Include="Graphics\picofont.h" />
+    <ClInclude Include="GUI_Kernel.h" />
+    <ClInclude Include="GUI_Messages.h" />
     <ClInclude Include="Interrupts\IDT.h" />
     <ClInclude Include="Interrupts\Interrupts.h" />
     <ClInclude Include="Interrupts\PIC.h" />

MyOS_1/MyOS_1.vcxproj.filters

@@ -64,6 +64,12 @@
     <Filter Include="Header Files\Tasks">
       <UniqueIdentifier>{b27b41e5-298f-4e04-9dea-743123199d72}</UniqueIdentifier>
     </Filter>
+    <Filter Include="Header Files\GUI">
+      <UniqueIdentifier>{441e1d72-2ac6-46dd-b47e-a3a9f01acb81}</UniqueIdentifier>
+    </Filter>
+    <Filter Include="Source Files\GUI">
+      <UniqueIdentifier>{ed1bb142-e86a-48ef-85ae-82740aea315c}</UniqueIdentifier>
+    </Filter>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="paging.c">
@@ -201,6 +207,9 @@
     <ClCompile Include="Tasks\Dispatcher.c">
       <Filter>Source Files\Tasks</Filter>
     </ClCompile>
+    <ClCompile Include="GUI_Kernel.c">
+      <Filter>Source Files\GUI</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="misc.h">
@@ -341,6 +350,12 @@
     <ClInclude Include="Drivers\mouse.h">
       <Filter>Source Files\Drivers</Filter>
     </ClInclude>
+    <ClInclude Include="GUI_Kernel.h">
+      <Filter>Header Files\GUI</Filter>
+    </ClInclude>
+    <ClInclude Include="GUI_Messages.h">
+      <Filter>Header Files\GUI</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <Text Include="Referenced_Reading.txt">

MyOS_1/Tasks/Context.h

@@ -21,6 +21,7 @@ typedef struct CONTEXT_INFO
     char imageName[MAX_IMAGE_NAME_LENGTH];
     bool inUse;
     bool exclusive; // True to disable switching to any other tasks
+    uint32_t PID;
     // ? What else?
 } CONTEXT_INFO, PROCESS_CONTROL_BLOCK;
 
@@ -52,6 +53,8 @@ extern PROCESS_CONTROL_BLOCK tasks[MAX_TASKS];
 extern int ticksLeftInTask;
 extern int currentTask;
 
+extern uint32_t nextPID;
+
 extern bool multiEnable; // TEMPTEMP
 
 void DispatchNewTask(uint32_t programStart, uint32_t stackSize, const char *imageName, bool exclusive);

MyOS_1/Tasks/Dispatcher.c

@@ -7,7 +7,7 @@ READY_QUEUE_ENTRY *readyQueueHead = NULL;
 
 int currentTask = 0;   // 0 is for the main kernel thread
 int ticksLeftInTask = TICKS_PER_TASK;
-
+uint32_t nextPID = 1000;
 
 // This must be global so we can access it while playing with the stack in ways the compiler can't predict
 uint32_t stackPtr;
@@ -61,6 +61,7 @@ void DispatchNewTask(uint32_t programStart, uint32_t stackSize, const char *imag
     tasks[taskSlot].ESP = stackPtr;
     strncpy(tasks[taskSlot].imageName, imageName, MAX_IMAGE_NAME_LENGTH - 1);
     tasks[taskSlot].inUse = true;
+    tasks[taskSlot].PID = nextPID++;
 
     // Create ready queue entry
     READY_QUEUE_ENTRY *queueEntry;