509 lines
8.5 KiB
Z80 Assembly
509 lines
8.5 KiB
Z80 Assembly
.global tasking_init
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tasking_init:
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ld bc, (next_pid)
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push bc
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pop de
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inc de
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ld (next_pid), de
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push bc
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call allocate_process
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push bc
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pop ix
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pop bc
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push bc
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ld (ix+2), 0x3
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ld (ix+3), 0xF
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ld (ix+4), 0x0
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ld (ix+9), c
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ld (ix+10), b
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push ix
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pop iy
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ld bc, 11
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add iy, bc
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ld c, 0
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task_init_pmap_set_loop:
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call get_frame
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ld (iy+0), b
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ld (iy+1), d
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ld (iy+2), e
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inc iy
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inc iy
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inc iy
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inc c
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cp 12
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jp nz, task_init_pmap_set_loop
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pop bc
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jp schedule_process
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.global new_process
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; Creates a new process
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; Entry point in HL, page mapping pointer in IY
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new_process:
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ld bc, (next_pid)
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push bc
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pop de
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inc de
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ld (next_pid), de
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push bc
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push hl
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call allocate_process
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pop hl
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push bc
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pop ix
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pop bc
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push bc
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ld (ix+9), c
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ld (ix+10), b
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ld bc, 0
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ld (ix+5), c
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ld (ix+6), b
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/* ld (ix+7), e */
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/* ld (ix+8), d */
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pop bc
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push hl
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push bc
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push iy
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pop hl
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push ix
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pop iy
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ld de, 11
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add iy, de
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ld b, 12
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new_p_pmap_set_loop:
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ld a, (hl)
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ld (iy+0), a
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inc hl
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ld a, (hl)
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ld (iy+1), a
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inc hl
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ld a, (hl)
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ld (iy+2), a
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inc hl
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inc iy
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inc iy
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inc iy
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djnz new_p_pmap_set_loop
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new_p_sp_set:
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push ix
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call get_free_frame
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new_p_after_gff:
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pop ix
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pop de
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push bc
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push de
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pop bc
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push hl
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push de
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call get_process_ptr
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new_p_after_gpp:
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pop de
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push bc
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pop ix
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pop hl
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pop bc
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ld (ix+2), c
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ld (ix+3), l
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ld (ix+4), h
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ld (ix+0), 0xEA
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ld (ix+1), 0xFF
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ld b, c
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ld c, 0xE
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push de
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push hl
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pop de
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push ix
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call set_frame
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pop ix
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new_p_ep_set:
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pop bc
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pop hl
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ld (0xEFFE), hl
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; Schedules the process with the pid in BC
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schedule_process:
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ld hl, (ready_to_run_head)
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ld a, h
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cp 0
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jp nz, block1
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ld a, l
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cp 0
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jp nz, block1
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jp end1
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block1:
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push bc
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push hl
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pop bc
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call get_process_ptr
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push bc
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pop iy
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pop bc
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push bc
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/* ld (iy+7), c */
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/* ld (iy+8), b */
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call get_process_ptr
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push bc
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pop ix
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pop bc
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ld (ix+5), l
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ld (ix+6), h
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ld (ready_to_run_head), bc
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ret
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end1:
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ld hl, (current_process)
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ld a, h
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cp 0
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jp nz, block2
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ld a, l
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cp 0
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jp nz, block2
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jp block3
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block2:
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ld (ready_to_run_head), bc
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ret
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block3:
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ld (current_process), bc
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ret
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.global yield
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yield:
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push ix
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ld ix, (ready_to_run_head)
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ld a, ixh
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cp 0
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jp nz, end3
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ld a, ixl
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cp 0
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jp nz, end3
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pop ix
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ret
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end3:
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pop ix
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; Save old process context
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push af
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push bc
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push de
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push hl
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exx
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ex af, af'
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push af
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push bc
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push de
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push hl
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exx
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ex af, af'
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push ix
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push iy
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ld bc, (current_process)
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call get_process_ptr
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push bc
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pop ix
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ld de, 11
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add ix, de
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call pmap_set
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ld bc, (current_process)
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call get_process_ptr
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push bc
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pop iy
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ld hl, 0
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add hl, sp
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ld (iy+0), l
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ld (iy+1), h
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yield_list_manip:
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; Get next process into ix, unlink it from the
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; ready to run list, and link the current process in
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; Logic:
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; next_process = ready_to_run_head -> pid
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; if (current_process->pid == 1) {
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; ready_to_run_head = 0
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; } else {
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; current_process->next = ready_to_run_head->next
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; ready_to_run_head = current_process
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; }
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; current_process = next_process
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ld ix, (ready_to_run_head)
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push ix
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pop bc
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call get_process_ptr
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ylm_gpp_done:
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push bc
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pop ix
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ld e, (ix+9)
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ld d, (ix+10)
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ld l, (ix+5)
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ld h, (ix+6)
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push hl
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push de
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push ix
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ld bc, (current_process)
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call get_process_ptr
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ylm_gpp2_done:
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pop ix
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pop de
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pop hl
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push bc
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pop iy
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ld a, (iy + 9)
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cp 1
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jp nz, else4
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xor a
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ld (ready_to_run_head), a
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ld (ready_to_run_head+1), a
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jp end4
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else4:
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ld (iy+5), l
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ld (iy+6), h
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ld bc, (current_process)
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ld (ready_to_run_head), bc
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end4:
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ld (current_process), de
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yield_sp_page_set:
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push ix
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ld de, 11
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add ix, de
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call pmap_load
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ysps_pl_done:
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pop ix
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; Load next process context
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ld b, (ix+2)
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ld c, 0xF
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ld e, (ix+3)
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ld d, (ix+4)
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ld iy, vmem_mapping_card
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ld (iy+0xF), b
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ld iy, vmem_mapping_bank_low
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ld (iy+0xF), e
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ld iy, vmem_mapping_bank_high
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ld (iy+0xF), d
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ld a, e
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out (c), a
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ld a, c
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or 0x20
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ld c, a
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ld a, d
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or 0x80
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out (c), a
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ld bc, (current_process)
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call get_process_ptr
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push bc
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pop ix
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yield_sp_load:
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ld l, (ix+0)
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ld h, (ix+1)
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ld sp, hl
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pop iy
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pop ix
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pop hl
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pop de
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pop bc
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pop af
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exx
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ex af, af'
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pop hl
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pop de
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pop bc
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pop af
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ret
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ready_to_run_head: .ds.b 2
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current_process: .ds.b 2
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next_pid: .dc.w 1
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process_allocation_bitmap: .ds.b 128
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process_heap_pages: .ds.b 48
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; Given a pid BC, return the pointer to the process or 0 if it's nonexistent, mapping the right page in if necessary
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; Clobbers A, BC, DE, HL, and IX
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get_process_ptr:
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push bc
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ld a, c
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and 0x7
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sla a
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sla a
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sla a
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or 0xC7
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ld (set_ins+1), a
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; Shift bc right 3 times to get the byte number in c
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srl b
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rr c
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srl b
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rr c
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srl b
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rr c
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ld hl, process_allocation_bitmap
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add hl, bc
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ld a, (hl)
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set_ins: set 0, a
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ld (hl), a
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pop bc
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push bc
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; Shift bc right 6 times to get the page number in c
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push bc
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pop hl
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xor a
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add hl, hl
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rla
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add hl, hl
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rla
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ld l, h
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ld h, a
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push hl
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pop bc
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; Multiply the page number by 3 to get the start offset in the table
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add hl, bc
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add hl, bc
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push hl
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pop bc
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ld hl, process_heap_pages
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add hl, bc
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ld a, (hl)
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cp 0
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jp z, not_allocated
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ld c, 0xE
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ld b, (hl)
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inc hl
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ld e, (hl)
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inc hl
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ld d, (hl)
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call set_frame
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pop bc
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ld a, c
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and 0x3F
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ld c, a
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ld b, 0
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; Shift BC right 6 bits (BC=BC*64)
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push bc
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pop hl
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xor a
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srl h
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rr l
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rra
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srl h
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rr l
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rra
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ld h, l
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ld l, a
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push hl
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pop bc
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ld a, b
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add a, 0xE0
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ld b, a
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ret
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not_allocated:
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pop bc
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ld bc, 0
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ret
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; Given a pid BC, allocate the space for that process and return a pointer to it in BC
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; Clobbers A, DE, HL, and IX
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allocate_process:
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push bc
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ld a, c
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and 0x7
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sla a
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sla a
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sla a
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or 0xC7
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ld (set_ins_2+1), a
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; Shift bc right 3 times to get the byte number in c
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srl b
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rr c
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srl b
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rr c
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srl b
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rr c
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ld hl, process_allocation_bitmap
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add hl, bc
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ld a, (hl)
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set_ins_2: set 0, a
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ld (hl), a
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pop bc
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push bc
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; Shift bc right 6 times to get the page number in c
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push bc
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pop hl
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xor a
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add hl, hl
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rla
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add hl, hl
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rla
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ld l, h
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ld h, a
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push hl
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pop bc
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; Multiply the page number by 3 to get the start offset in the table
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add hl, bc
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add hl, bc
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push hl
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pop bc
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ld hl, process_heap_pages
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add hl, bc
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ld a, (hl)
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cp 0
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jp nz, return_ptr
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push hl
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call get_free_frame
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pop de
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ld a, c
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ld (de), a
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inc de
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ld a, l
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ld (de), a
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inc de
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ld a, h
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ld (de), a
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dec de
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dec de
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push de
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pop hl
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return_ptr:
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ld c, 0xE
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ld b, (hl)
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inc hl
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ld e, (hl)
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inc hl
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ld d, (hl)
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call set_frame
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pop bc
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ld a, c
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and 0x3F
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ld c, a
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ld b, 0
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; Shift BC left 6 bits (BC=BC*64)
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xor a
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srl b
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rr c
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rra
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srl b
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rr c
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rra
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ld b, c
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ld c, a
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ld a, b
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add a, 0xE0
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ld b, a
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ret
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; Given a pid in BC, free the processes memory
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; Clobber A, BC, and HL
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free_process:
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ld a, c
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and 0x7
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sla a
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sla a
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sla a
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or 0x87
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ld (res_ins+1), a
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; Shift bc right 3 times to get the byte number in c
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srl b
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rr c
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srl b
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rr c
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srl b
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rr c
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ld hl, process_allocation_bitmap
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add hl, bc
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ld a, (hl)
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res_ins: res 0, a
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ld (hl), a
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ret
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