ZX Spectrum tape pulses measure

tape_port.asm

;
;	Tape bit lengths
;


	org 0x8000
	
	di
	ld sp, stack
	
restart:	
	ld ix, values ; start loading address

	call wait_for_start
loop:	
	call get_bit_length
	ld (ix + 0), e
	inc ix
	ld a, ixh
	or a
	jr z, stop
	jr loop
stop:
	halt ; watch'em at 0x9000
	jp restart
	
wait_for_start: 
	xor a
	in a, (0xFE) ; initial read
	and 0x40
	ld d, a	

get_bit_length: ; 
	ld e, 0	
loop_bit:
	ld c, a
	inc e				 	
	in a, (0xFE)		 
	and 0x40			 
	cp d		
	jr z, loop_bit		 
	ld d, a	
	ret
	
	defs 32
stack:
	
	org 0x9000
values:
	
END 0x8000