Add get_current_task_id

fox32os.def

@@ -10,6 +10,8 @@ parse_fxf_binary: jmp [0x00000910]
 new_task:            jmp [0x00000A10]
 yield_task:          jmp [0x00000A14]
 end_current_task:    jmp [0x00000A18]
+get_current_task_id: jmp [0x00000A1C]
+get_unused_task_id:  jmp [0x00000A20]
 
 ; memory jump table
 allocate_memory:     jmp [0x00000B10]

kernel/main.asm

@@ -26,6 +26,8 @@ jump_table:
     data.32 new_task
     data.32 yield_task
     data.32 end_current_task
+    data.32 get_current_task_id
+    data.32 get_unused_task_id
 
     ; memory jump table
     org.pad 0x00000B10

kernel/task.asm

@@ -106,10 +106,33 @@ get_unused_task_id_loop:
     inc r0
     cmp r0, 32
     iflt jmp get_unused_task_id_loop
-    ; if we reach this point, then add task IDs are used
+    ; if we reach this point, then all task IDs are used
     mov r0, 0
     ret
 
+; get the task ID of the currently running task
+; inputs:
+; none
+; outputs:
+; r0: task ID
+get_current_task_id:
+    push r2
+    push r3
+    push r4
+    push r5
+    push r6
+
+    mov r0, current_task
+    call task_load
+    mov r0, r2
+
+    pop r6
+    pop r5
+    pop r4
+    pop r3
+    pop r2
+    ret
+
 task_load:
     mov r2, [r0] ; task ID
     add r0, 4