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update Thread_switch for preemption

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Christoph Urlacher
2022-07-04 21:23:31 +02:00
parent 6ad1d9e525
commit 1cac6b3a58
1 changed files with 37 additions and 11 deletions
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48
c_os/kernel/threads/Thread.asm
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@ -86,28 +86,54 @@ Thread_switch:
; *
; * Hier muss Code eingefuegt werden
; *
;; Make eax point to beginning of regs_now in memory
mov eax, [esp + 0x4]
;; Save current coroutine registers
mov [eax + ebx_offset], ebx
;; == High address ==
;; *REGS_THEN
;; *REGS_NOW
;; RET ADDR
;; SP --> EAX
;; == Low address ==
push eax ; backup eax before using it as index
mov eax, [esp + 0x8]
pushf ; store eflags
pop ebx
mov [eax + efl_offset], ebx
add esp, 0x4 ; store the original esp
mov [eax + esp_offset], esp
sub esp, 0x4
mov [eax + ebx_offset], ebx ; store other regs
mov [eax + esi_offset], esi
mov [eax + edi_offset], edi
mov [eax + ebp_offset], ebp
mov [eax + esp_offset], esp
mov [eax + ecx_offset], ecx
mov [eax + edx_offset], edx
;; Make eax point to beginning of regs_then in memory
pop ebx ; store eax
mov [eax + eax_offset], ebx
;; Load next coroutine registers ============================================================
mov eax, [esp + 0x8]
;; Load next coroutine registers
mov ebx, [eax + ebx_offset]
mov ebx, [eax + efl_offset] ; restore eflags
push ebx ; could be pushed directly from address but i didn't want to specify wordsize
popf
mov ebx, [eax + ebx_offset] ; restore other regs
mov esi, [eax + esi_offset]
mov edi, [eax + edi_offset]
mov ebp, [eax + ebp_offset]
mov esp, [eax + esp_offset]
mov ecx, [eax + ecx_offset]
mov edx, [eax + edx_offset]
;; Stackpointer now points to kickoff address, ret jumps there
;; NOTE: The stackpointer only points to kickoff if the next coroutine was just initialized.
mov eax, [eax + eax_offset] ; restore eax
;; Enable interrupts again
sti
;; NOTE: The stackpointer points to kickoff if the next coroutine was just initialized.
;; Otherwise it just points somewhere in the next coroutines stack
ret