16% safe fast link protocol for Axe

p_GetByte:
    .db __GetByteEnd-$-1
    di
    in  a,(0)
    cp  2           ;Check to see if sender is ready
    ccf
    sbc hl,hl
    ret c           ;If not, then return
    out (0),a           ;Otherwise, relay a confirmation
    ex  (sp),hl         ;Wait for confirmation to be read
    ex  (sp),hl         ;Store received byte in l
    inc l           ;Done signal will be when bit 0 of l is shifted out
    ld  a,h
    out (0),a           ;Reset the port to receive data
__GetByteLoop:
    in  a,(0)           ;Check if a new bit has been sent
    srl a
    jr  z,__GetByteLoop
    rl  l           ;Shift the new bit in and check if done
    jr  nc,__GetByteLoop    ;Keep looping if we haven't got all the bits
    ret             ;Otherwise, we're done
__GetByteEnd:

p_SendByte:
    .db __SendByteEnd-$-1
    di              ;Byte to send in e
    ld  bc,$0803        ;Bit counter in b, bit mask in c
    ld  a,2
    out (0),a           ;Indicate we are ready to send
__SendByteTimeout:
    dec hl          ;Wait for confirmation until hl is decreased to 0
    ld  a,h
    or  l
    jr  z,__SendByteDone
    in  a,(0)           ;Check for confirmation
    and c
    jr  nz,__SendByteTimeout    ;Keep looping till we get it
__SendByteLoop:
    sla e           ;Rotate bits left
    ld  a,c
    out (0),a           ;Send bit separation signal
    sbc a,2
    out (0),a           ;Send the bit shifted out
    djnz    __SendByteLoop      ;Loop if there are more bits to send
    xor a
__SendByteDone:
    out (0),a           ;Reset the port
    ret             ;We're done
__SendByteEnd: