.include "bios.inc"

.area   TAPELOAD (ABS)
.org    TAPE_LOADER_ROM_ADDRESS

COMP_PORT       =     0x18

WORK_BASE       =     0x0B000
LOAD_START      =     0x08000
LOAD_LIMIT_HI   =     0x0B0
STACK_TOP       =     0x0BFFF

OLD_SP          =     WORK_BASE+0x00

start:
        ld      (OLD_SP), sp
        ld      sp, #STACK_TOP

        di

poll_loop:

        ; Read from the hardware port COMP_PORT
        in      a, (COMP_PORT)
        out     (COMP_PORT), a
        
        ; Save the raw port status in register B
        ld      b, a

        ; Print a carriage return '\r' (ASCII 0x0D)
        ld      a, #0x0D
        call    BIOS_PUTC

        ; Restore the port status and isolate the relevant bit
        ; (Assuming bit 0 determines 0 or 1; adjust 'and' mask if it is a different bit)
        ld      a, b
        and     #0x01

        ; Convert the binary 0 or 1 into ASCII '0' (0x30) or '1' (0x31)
        add     a, #0x30
        
        ; Print the '0' or '1' character
        call    BIOS_PUTC

        ; Infinite loop: poll continuously
        jr      poll_loop

        ld      sp, (OLD_SP)
        ei
        ret