;;
;;
;; args:
;;   X: zero page offset
;;   Y: length
lcd_hex:        NOP i

        ;; top nib
_hex_loop:      LDA zp,x 0
                LSR A
                LSR A
                LSR A
                LSR A
                CMP # a
                BCS r :_hex_nib0_af
_hex_nib0_09:     CLC i
                  ADC # 30
                  BRA r :_hex_nib0_out
_hex_nib0_af:     CLC i
                  ADC # 37
_hex_nib0_out:    JSR a :lcd_w_rs1

        ;; bottom nib
                LDA zp,x 0
                AND # f
                CMP # a
                BCS r :_hex_nib1_af
_hex_nib1_09:     CLC i
                  ADC # 30
                  BRA r :_hex_nib1_out
_hex_nib1_af:     CLC i
                  ADC # 37
_hex_nib1_out:    JSR a :lcd_w_rs1

                DEX i
                DEY i
                BNE r :_hex_loop

                RTS s