debug.z80

print_debug_keymatrix:
                ; render the keyboard matrix
                ld hl, 0
                ld (hl), 255
                inc hl
                ld (hl), 0
                inc hl
                ld (hl), 255
                inc h
                ld l,0

                ld de, keyb_buffer
                ld c,9
    @outer_loop:
                ld b,8
                ld a,(de)
    @inner_loop:
                rrca
                jr c, @key_detected
    @key_not_detected:
                ld (hl), 0
                jr @next
    @key_detected:
                ld (hl), 255
    @next:
                inc hl
                ld (hl), 0
                inc hl
                djnz @-inner_loop
                inc de
                inc h
                ld l,0
                dec c
                jr nz, @-outer_loop

    @keys_and_latches:
                inc h
                inc h
                ld l,0
                ld a, (controller_flags_dirs)
                ld b,4
    @inner_loop:
                rrca
                jr c, @+key_detected
    @key_not_detected:
                ld (hl), 17*1
                jr @+next
    @key_detected:
                ld (hl), 17*3
    @next:
                inc hl
                ld (hl), 0
                inc hl
                djnz @-inner_loop
                ret

debug_wait_for_a_bit:
                ; useful to insert a reasonably size delay, good for setting
                ; breakpoints in simice
                ld c, 0
    @loop1:
                ld b, 0
    @loop2:
                nop
                nop
                nop
                nop
                nop
                nop
                nop
                nop
                djnz @-loop2
                dec c
                jr nz, @-loop1
                ret


fatal:
                ; this is like our version of assert. called when something
                ; has gone horribly wrong, during a DEBUG build
                ld a, c
                inc c
                and 0x17
                out (BORDER), a
                nop
                jp fatal