kernel/task: Add save_state_and_yield_task

fox32os.def

@@ -13,6 +13,7 @@ end_current_task:          jmp [0x00000A18]
 get_current_task_id:       jmp [0x00000A1C]
 get_unused_task_id:        jmp [0x00000A20]
 is_task_id_used:           jmp [0x00000A24]
+save_state_and_yield_task: jmp [0x00000A28]
 
 ; memory jump table
 allocate_memory:           jmp [0x00000B10]

kernel/main.asm

@@ -29,6 +29,7 @@ jump_table:
     data.32 get_current_task_id
     data.32 get_unused_task_id
     data.32 is_task_id_used
+    data.32 save_state_and_yield_task
 
     ; memory jump table
     org.pad 0x00000310

kernel/task.asm

@@ -45,6 +45,83 @@ yield_task:
 
     jmp yield_task_0
 
+; push all registers and switch to the next task in the queue
+; inputs:
+; none
+; outputs:
+; none
+save_state_and_yield_task:
+    push rfp
+    push r31
+    push r30
+    push r29
+    push r28
+    push r27
+    push r26
+    push r25
+    push r24
+    push r23
+    push r22
+    push r21
+    push r20
+    push r19
+    push r18
+    push r17
+    push r16
+    push r15
+    push r14
+    push r13
+    push r12
+    push r11
+    push r10
+    push r9
+    push r8
+    push r7
+    push r6
+    push r5
+    push r4
+    push r3
+    push r2
+    push r1
+    push r0
+
+    call yield_task
+
+    pop r0
+    pop r1
+    pop r2
+    pop r3
+    pop r4
+    pop r5
+    pop r6
+    pop r7
+    pop r8
+    pop r9
+    pop r10
+    pop r11
+    pop r12
+    pop r13
+    pop r14
+    pop r15
+    pop r16
+    pop r17
+    pop r18
+    pop r19
+    pop r20
+    pop r21
+    pop r22
+    pop r23
+    pop r24
+    pop r25
+    pop r26
+    pop r27
+    pop r28
+    pop r29
+    pop r30
+    pop r31
+    pop rfp
+    ret
+
 ; switch to the next task without adding the current task back into the queue
 ; this will automatically free the task's code and stack blocks
 ; inputs: