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kickstart_task.a65
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; Return the next free task ID
; XXX - Task ID $FF is hypervisor/operating system
; XXX - For now just lie, and always say task $00 is next.
; We should have a process allocation table that we consult.
; (actual suspended processes should be held on SD card in files)
task_get_next_taskid:
lda #$00
rts
task_set_c64_memorymap:
; set contents of CPU registers for exit from hypervisor mode
lda #$00
sta hypervisor_a
sta hypervisor_x
sta hypervisor_y
sta hypervisor_z
sta hypervisor_b
lda #$ff
sta hypervisor_spl
lda #$01
sta hypervisor_sph
lda #$F7 ; All flags except decimal mode
sta hypervisor_flags
lda #$00
sta hypervisor_maplolo
sta hypervisor_maplohi
sta hypervisor_maphilo
sta hypervisor_maphihi
sta hypervisor_maplomb
sta hypervisor_maphimb
lda #$3f
sta hypervisor_cpuport00
sta hypervisor_cpuport01
lda #$00
sta hypervisor_iomode ; C64 IO map
; XXX - disable C65 ROM maps
rts
task_set_pc_to_reset_vector:
; Set PC from $FFFC in ROM, i.e., $802FFFC
ldx #<reset_vector
ldy #>reset_vector
ldz #$02
lda #$00
jsr longpeek
lda kickstart_scratchbyte0
sta hypervisor_pcl
ldx #<reset_vector
inx
ldy #>reset_vector
ldz #$02
lda #$00
jsr longpeek
lda kickstart_scratchbyte0
sta hypervisor_pch
rts
; Set all page entries and current page number to all zeroes
; so that we don't think any page is loaded.
; XXX - Is all zeroes the best value here? Physical page 0 is $00000000, which
; is in chipram. It might be legitimate to try to map that. Perhaps we should set
; the pages to $FFFF instead (but that would reduce available VM space by 16KB).
; Physical page 0 is probably reasonable for now. We can revisit as required.
task_clear_pagetable:
lda #$00
ldx #<hypervisor_vm_currentpage_lo
tcp1: sta $d600,x
inx
cpx #[<hypervisor_vm_pagetable3_physicalpage_hi+1]
bne tcp1
rts
task_erase_processcontrolblock:
; Erase process control block
ldx #$00
txa
tabs1: sta currenttask_block,x
inx
bne tabs1
jsr task_clear_pagetable
; Mark all files as closed
jmp dos_clear_filedescriptors
task_new_processcontrolblock:
jsr task_erase_processcontrolblock
jsr task_get_next_taskid
sta currenttask_id
rts
; Initialise memory to indicate a new blank task.
; (actually, it will be a task preconfigured for C64/C65 mode)
task_asblankslate:
jsr task_new_processcontrolblock
jsr task_set_c64_memorymap
rts