Renesas H8/36912 Series User Manual page 45

Bit Bit Name
7 I
6 UI
5 H
4 U
3 N
2 Z
1 V
0 C
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Initial
Value R/W Description
1 R/W Interrupt Mask Bit
Masks interrupts other than NMI 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.
Undefined R/W User Bit
Can be written and read by software using the LDC, STC,
ANDC, ORC, and XORC instructions.
Undefined R/W 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.
Undefined R/W User Bit
Can be written and read by software using the LDC, STC,
ANDC, ORC, and XORC instructions.
Undefined R/W Negative Flag
Stores the value of the most significant bit of data as a
sign bit.
Undefined R/W Zero Flag
Set to 1 to indicate zero data, and cleared to 0 to indicate
non-zero data.
Undefined R/W Overflow Flag
Set to 1 when an arithmetic overflow occurs, and cleared
to 0 at other times.
Undefined R/W 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
Rev. 1.00, 11/03, page 17 of 376