NEC 78K/0 Series User Manual
65
CHAPTER 5 EXPLANATION OF INSTRUCTIONS
User's Manual U12326EJ4V0UM
Subtract Word
SUBW
Word Data Subtraction
[Instruction format]
SUBW dst, src
[Operation]
dst, CY
← dst – src
[Operand]
Mnemonic
Operand(dst,src)
SUBW
AX, #word
[Flag]
Z
AC
CY
×
×
×
[Description]
•
The source operand (src) specified by the 2nd operand is subtracted from the destination operand (dst)
specified by the 1st operand and the result is stored in the destination operand (dst) and the CY flag.
The destination operand can be cleared to 0 by equalizing the source operand (src) and the destination
operand (dst).
•
If the subtraction shows that dst is 0, the Z flag is set (1). In all other cases, the Z flag is cleared (0).
•
If the subtraction generates a borrow out of bit 15, the CY flag is set (1). In all other cases, the CY flag is
cleared (0).
•
As a result of subtraction, the AC flag becomes undefined.
[Description example]
SUBW AX, #ABCDH; ABCDH is subtracted from the AX register contents and the result is stored in the AX
register.