HD6433713 datasheet(30/324 Pages) RENESAS

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Bit 7—Interrupt Mask Bit (I): When this bit is set to 1, interrupts are masked. This bit is set to 1

automatically at the start of exception handling. The interrupt mask bit may be read and written

by software. For further details, see 3.2.2, Interrupts.

Bit 6—User Bit (U): Can be written and read by software (using the LDC, STC, ANDC, ORC,

and XORC instructions).

Bit 5—Half-Carry Flag (H): 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 is cleared to 0

otherwise.

The H flag is used implicitly by the DAA and DAS instructions.

When the ADD.W, SUB.W, or CMP.W instruction is executed, the H flag is set to 1 if there is a

carry or borrow at bit 11, and is cleared to 0 otherwise.

Bit 4—User Bit (U): Can be written and read by software (using the LDC, STC, ANDC, ORC,

and XORC instructions).

Bit 3—Negative Flag (N): Indicates the most significant bit (sign bit) of the result of an

instruction.

Bit 2—Zero Flag (Z): Set to 1 to indicate zero data, and cleared to 0 to indicate non-zero data.

Bit 1—Overflow Flag (V): Set to 1 when an arithmetic overflow occurs, and cleared to 0 at other

times.

Bit 0—Carry Flag (C): Set to 1 when a carry occurs, and cleared to 0 otherwise. Used by:

•

Add instructions, to indicate a carry

•

Subtract instructions, to indicate a borrow

•

Shift and rotate instructions, to store the value shifted out of the end bit

The carry flag is also used as a bit accumulator by bit manipulation instructions.

Some instructions leave some or all of the flag bits unchanged. The LDC, STC, ANDC, ORC, and

XORC instructions enable the CPU to load and store the CCR, and to set or clear selected bits by

logic operations. The N, Z, V, and C flags are used as branching conditions for conditional

branching (Bcc) instructions.

Refer to the H8/300L Series Programming Manual for the action of each instruction on the flag

bits.

HD6433713 Datasheet(PDF) 30 Page - Renesas Technology Corp