h8s-2161b Renesas Electronics Corporation., h8s-2161b Datasheet - Page 90

• Manufacturer Part Number: h8s-2161b
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

Section 2 CPU
Bit
7
6
5
4
3
2
1
0
Rev. 3.00 Mar 21, 2006 page 36 of 788
REJ09B0300-0300
Bit Name
I
UI
H
U
N
Z
V
C
Initial Value
1
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Description
Interrupt Mask Bit
Masks interrupts when set to 1. NMI is accepted
regardless of the I bit setting. The I bit is set to 1 at the
start of an exception-handling sequence. For details, refer
to section 5, Interrupt Controller.
User Bit or Interrupt Mask Bit
Can be written to and read from by software using the
LDC, STC, ANDC, ORC, and XORC instructions.
Half-Carry Flag
When the ADD.B, ADDX.B, SUB.B, SUBX.B, CMP.B or
NEG.B instruction is executed, this flag is set to 1 if there
is a carry or borrow at bit 3, and cleared to 0 otherwise.
When the ADD.W, SUB.W, CMP.W, or NEG.W
instruction is executed, the H flag is set to 1 if there is a
carry or borrow at bit 11, and cleared to 0 otherwise.
When the ADD.L, SUB.L, CMP.L, or NEG.L instruction is
executed, the H flag is set to 1 if there is a carry or
borrow at bit 27, and cleared to 0 otherwise.
User Bit
Can be written to and read from by software using the
LDC, STC, ANDC, ORC, and XORC instructions.
Negative Flag
Stores the value of the most significant bit of data as a
sign bit.
Zero Flag
Set to 1 to indicate zero data, and cleared to 0 to indicate
non-zero data.
Overflow Flag
Set to 1 when an arithmetic overflow occurs, and cleared
to 0 otherwise.
Carry Flag
Set to 1 when a carry occurs, and cleared to 0 otherwise.
Used by
The carry flag is also used as a bit accumulator by bit
manipulation instructions.
Add instructions, to indicate a carry
Subtract instructions, to indicate a borrow
Shift and rotate instructions, to indicate a carry