_lshiftc:
; inputs: iy = ptr to src, hl = ptr to dest, a = shift count
; ouputs: none
; destroys: a, b, c, flags
; algorithm:
;		byte shift: shift by between 1 and 32 (inclusive) bytes by:
;			shift a to the right 3x (div 8), then and a with 30 to constrain to 30 or less
;		 	if a == 0, skip to the bit shift section
;			set the first a bytes of de to 0
;			copy 32 - a bytes from hl to de + a
;		bit shift: shift by between 1 and 7 (inclusive) bits by:
;			restore original a, then and with 7 to return a value mod 8
;			return if 0
;			shift the 32 bytes at hl to the left a times
	push af
		push hl
			push iy

				srl a
				srl a
				srl a

				or a
				jr z, .skip_byte_shift

				; add a to hl
				ld bc, 0
				ld c, a
				add hl, bc

				; sub 32 - a
				ld b, a
				ld a, 32					; set c to 32
				sub a, b

				ld b, a
.loop_xor_bytes:
				ld a, (iy)
				xor (hl)
				ld (hl), a
				inc iy
				inc hl
				djnz .loop_xor_bytes

.skip_byte_shift:
			pop iy
		pop hl			; dest into hl now
	pop af				; return original a
	and a, 7			; and a with 7 to get a % 8
	ret z
	ld b, a
	ld a, 1
.ishiftc:
	rlca
	djnz .ishiftc
	ld c, a
	ld b, 32
	xor a
.shift_bits:
	ld e, (iy)
	ld d, c
	mlt de
	add a, e
	xor (hl)
	ld (hl), a
	ld a, d
	inc hl
	djnz .shift_bits
	ret