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Add stack block pointer to each task

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This allows the stack block to automatically be freed when the task
ends.
This commit is contained in:
Ry 2022-06-24 16:37:43 -07:00
parent 606ec0283e
commit 04761c1a07
2 changed files with 20 additions and 9 deletions
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1
kernel/main.asm
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@ -97,6 +97,7 @@ run_startup_task:
mov r0, 0
mov r2, rsp
sub r2, 4
mov r4, 0 ; don't attempt to free any stack block if the task ends
call new_task
; when the startup file yields for the first time, we'll end up back here.

28
kernel/task.asm
View File

@ -5,15 +5,17 @@
; r0: task ID
; r1: pointer to task code
; r2: pointer to task stack
; r3: pointer to memory block to free when task ends, or zero for none
; r3: pointer to code block to free when task ends, or zero for none
; r4: pointer to stack block to free when task ends, or zero for none
; outputs:
; none
new_task:
; mark this task ID as used
bse [task_id_bitmap], r0
mov r6, r4 ; stack block pointer
mov r5, r3 ; code block pointer
mov r4, r2 ; stack pointer
mov r5, r3 ; memory block pointer
mov r3, r1 ; instruction pointer
mov r2, r0 ; task ID
@ -42,7 +44,7 @@ yield_task:
jmp yield_task_0
; switch to the next task without adding the current task back into the queue
; this will automatically free the task's code block
; this will automatically free the task's code and stack blocks
; inputs:
; none
; outputs:
@ -51,7 +53,10 @@ end_current_task:
mov r0, current_task ; get the current task struct
call task_load
bcl [task_id_bitmap], r2 ; mark this task ID as unused
mov r0, r5 ; memory block pointer
mov r0, r5 ; code block pointer
cmp r0, 0
ifnz call free_memory
mov r0, r6 ; stack block pointer
cmp r0, 0
ifnz call free_memory
end_current_task_no_mark_no_free:
@ -112,7 +117,9 @@ task_load:
add r0, 4
mov r4, [r0] ; stack pointer
add r0, 4
mov r5, [r0] ; memory block pointer
mov r5, [r0] ; code block pointer
add r0, 4
mov r6, [r0] ; stack block pointer
add r0, 4
ret
@ -123,7 +130,9 @@ task_store:
add r0, 4
mov [r0], r4 ; stack pointer
add r0, 4
mov [r0], r5 ; memory block pointer
mov [r0], r5 ; code block pointer
add r0, 4
mov [r0], r6 ; stack block pointer
add r0, 4
ret
@ -135,12 +144,13 @@ task_empty:
task_panic_str: data.str "Scheduler starved, task queue empty!" data.8 10 data.8 0
const TASK_SIZE: 16
const TASK_SIZE: 20
task_id_bitmap: data.32 0
current_task:
data.32 0 ; task ID
data.32 0 ; instruction pointer
data.32 0 ; stack pointer
data.32 0 ; memory block pointer
data.32 0 ; code block pointer
data.32 0 ; stack block pointer
task_queue_ptr: data.32 task_queue_bottom
task_queue_bottom: data.fill 0, 512 ; 32 tasks * 4 entries per task * 4 bytes per word = 512
task_queue_bottom: data.fill 0, 640 ; 32 tasks * 5 entries per task * 4 bytes per word = 640