SONIX SN8P2624 - 2.1.1.3 Look-up Table Description

SN8P2624
8-Bit Micro-Controller
SONiX TECHNOLOGY CO., LTD Page 16 Version 0.3
2.1.1.3 LOOK-UP TABLE DESCRIPTION
In the ROM’s data lookup function, Y register is pointed to middle byte address (bit 8~bit 15) and Z register is pointed
to low byte address (bit 0~bit 7) of ROM. After MOVC instruction executed, the low-byte data will be stored in ACC and
high-byte data stored in R register.
¾ Example: To look up the ROM data located “TABLE1”.
B0MOV Y, #TABLE1$M ; To set lookup table1’s middle address
B0MOV Z, #TABLE1$L ; To set lookup table1’s low address.
MOVC ; To lookup data, R = 00H, ACC = 35H
; Increment the index address for next address.
INCMS Z ; Z+1
JMP @F ; Z is not overflow.
INCMS Y ; Z overflow (FFH Æ 00), Æ Y=Y+1
NOP ;
;
@@: MOVC ; To lookup data, R = 51H, ACC = 05H.
… ;
TABLE1: DW 0035H ; To define a word (16 bits) data.
DW 5105H
DW 2012H
…
 Note: The Y register will not increase automatically when Z register crosses boundary from 0xFF to
0x00. Therefore, user must take care such situation to avoid loop-up table errors. If Z register
overflows, Y register must be added one. The following INC_YZ macro shows a simple method
to process Y and Z registers automatically.
¾ Example: INC_YZ macro.
INC_YZ MACRO
INCMS Z ; Z+1
JMP @F ; Not overflow
INCMS Y ; Y+1
NOP ; Not overflow
@@:
ENDM