Lecture 76 - Creating the ability to create and execute kernel commands

nibblebits · Nov 19, 2020 · 4ed3ccb · 4ed3ccb
1 parent ee37a5a
commit 4ed3ccb
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Showing 3 changed files with 43 additions and 1 deletion.
diff --git a/src/config.h b/src/config.h
@@ -33,4 +33,6 @@
 #define USER_DATA_SEGMENT 0x23
 #define USER_CODE_SEGMENT 0x1b
 
+#define PEACHOS_MAX_ISR80H_COMMANDS 1024
+
 #endif
diff --git a/src/idt/idt.c b/src/idt/idt.c
@@ -2,13 +2,17 @@
 #include "config.h"
 #include "kernel.h"
 #include "memory/memory.h"
+#include "task/task.h"
 #include "io/io.h"
 struct idt_desc idt_descriptors[PEACHOS_TOTAL_INTERRUPTS];
 struct idtr_desc idtr_descriptor;
 
+static ISR80H_COMMAND isr80h_commands[PEACHOS_MAX_ISR80H_COMMANDS];
+
 extern void idt_load(struct idtr_desc* ptr);
 extern void int21h();
 extern void no_interrupt();
+extern void isr80h_wrapper();
 
 void int21h_handler()
 {
@@ -49,15 +53,46 @@ void idt_init()
 
     idt_set(0, idt_zero);
     idt_set(0x21, int21h);
+    idt_set(0x80, isr80h_wrapper);
 
 
     // Load the interrupt descriptor table
     idt_load(&idtr_descriptor);
 }
 
-void isr80h_handle_command(int command, struct interrupt_frame* frame)
+void isr80h_register_command(int command_id, ISR80H_COMMAND command)
+{
+    if (command_id <= 0 || command_id >= PEACHOS_MAX_ISR80H_COMMANDS)
+    {
+        panic("The command is out of bounds\n");
+    }
+
+    if (isr80h_commands[command_id])
+    {
+        panic("Your attempting to overwrite an existing command\n");
+    }
+
+    isr80h_commands[command_id] = command;
+}
+
+void* isr80h_handle_command(int command, struct interrupt_frame* frame)
 {
+    void* result = 0;
+
+    if(command <= 0 || command >= PEACHOS_MAX_ISR80H_COMMANDS)
+    {
+        // Invalid command
+        return 0;
+    }
+
+    ISR80H_COMMAND command_func = isr80h_commands[command];
+    if (!command_func)
+    {
+        return 0;
+    }
 
+    result = command_func(frame);
+    return result;
 }
 
 void* isr80h_handler(int command, struct interrupt_frame* frame)

diff --git a/src/idt/idt.h b/src/idt/idt.h
@@ -2,6 +2,10 @@
 #define IDT_H
 
 #include <stdint.h>
+
+struct interrupt_frame;
+typedef void*(*ISR80H_COMMAND)(struct interrupt_frame* frame);
+
 struct idt_desc
 {
     uint16_t offset_1; // Offset bits 0 - 15
@@ -37,5 +41,6 @@ struct interrupt_frame
 void idt_init();
 void enable_interrupts();
 void disable_interrupts();
+void isr80h_register_command(int command_id, ISR80H_COMMAND command);
 
 #endif