extrn	.advptr, .inxm
;
; put byte c to buffer hl^.  No range checks
; a,f
.bput::	push h	! push d ! push b
	inx h	! inx h;		adv to size store
	mov c,m	! inx h ! mov b,m;	get size
	inx h	! inx h ! inx h;	point to ctr field
	call	.inxm ! inx h;		and decrement
	inx h	! inx h;		advance to write ptr
	mov e,m ! inx h ! mov d,m;	get read ptr
	push	d;			save, before advance
	call	.advptr;		advance modulo bc
	mov m,d	! dcx h ! mov m,e;	and save
	pop	d
	inx h	! inx h;		advance to buff base
	pop	b
	dad d	! mov m,c;		index and put char. clr cy.
	pop d	! pop h
	ret