; ---------------------------------------------------------------------------
; spi send/receive routine - block, with CS
; low addr in A, high addr in Y, count in X

.proc _spi_txrx_block: near
			sta $fe
			sty $ff
			ldy #0
			lda #$fe				; lower cs0
			sta SPI0_BASE+SPICSR
ssb_twt:	lda SPI0_BASE+SPISR		; get tx status on first pass
			and #$10				; test trdy
			beq	ssb_twt				; loop until ready
ssb_lp:		lda ($fe),y				; get tx byte
			sta SPI0_BASE+SPITXDR	; send tx
ssb_rwt:	lda SPI0_BASE+SPISR		; get rx status
			and #$08				; test rrdy
			beq	ssb_rwt				; loop until ready
			lda SPI0_BASE+SPIRXDR	; get rx
			sta ($fe),y				; save rx byte
			iny
			dex
			bne ssb_lp				; back to tx - assume ready
			lda #$ff				; raise cs0
			sta SPI0_BASE+SPICSR
			rts
.endproc