; Creates a new task to be run
; inputs:   de = pointer to filename
; outputs:  a  = status value
NewThread:
    call SafeInterruptDI
    push af
    push de
        call LoadExecutableToRAM
        if(SUCCESS)
            jr nz,_ ; failed to load
        call GetNextFreeThread
        if(OPEN_THREAD_SPACE)
            jr nz,_ ; no space for new threads to go
        ld (hl),STATE_STARTED
        inc hl      ; load the thread's state
        ld (hl),e
        inc hl
        ld (hl),d
        inc hl      ; load the exacutable address
        ex de,hl
        add hl,bc
        ex de,hl
        ld (hl),e
        inc hl
        ld (hl),d
        inc hl      ; load the stack address
    pop de
    ld (hl),e
    inc hl
    ld (hl),d       ; load the pointer to the filename into the thread entry
    pop af
    call SafeInterruptEI
    ld a,SUCCESS
    ret
_   pop de
    ld b,a
    pop af
    call SafeInterruptEI
    ld a,b
    ret

SafeInterruptDI:
    xor a       ;Set nc (interrupts)
    push af     ;Check interrupts
    pop af
    ld a,i      ;pe if interrupt
    di
        ret pe      ;Return if interrupts on
    dec sp      ;Otherwise, robust test
    dec sp
    pop af
    or a        ;Set nc (interrupts)
        ret nz      ;Return if interrupts on
    scf         ;Set c (no interrupts)
    ret         ;Return
; safely returns interrupts
; inputs    af = state flags
SafeInterruptEI:
    ret c
    ei
    ret