Zilog Z8F0130 - Manual (Page 21)

eZ8
™
CPU Core
User Manual
UM012820-0810 Architectural Overview
6
Interrupts, the Software Trap (TRAP) instruction, and Illegal Instruction
Traps all write value of the Flags Register to the stack. Executing an Inter-
rupt Return (IRET) instruction restores the value saved on the stack into
the Flags Register.
Carry Flag
The Carry flag (C) is 1 when the result of an arithmetic operation gener-
ates a carry out or a borrow into the most significant bit (Bit 7) of the data.
Otherwise, the Carry flag is 0. Some bit rotate or shift instructions also
affect the Carry flag. There are three instructions available for directly
changing the value of the Carry Flag:
•
Complement Carry Flag (CCF)
•
Reset Carry Flag (RCF)
•
Set Carry Flag (SCF)
Figure 2. Flags Register
C Z S V D H F2 F1 Flags Register
Bit
0
Bit
7
Half Carry Flag
Decimal Adjust Flag
Overflow Flag
Sign Flag
Zero Flag
Carry Flag
User Flags