HD6432351 datasheet(67/1025 Pages) RENESAS

67 / 1025 page

Section 2 CPU

Rev. 3.00 Sep 15, 2006 page 33 of 988

REJ09B0330-0300

Bits 2 to 0—Interrupt Mask Bits (I2 to I0): These bits designate the interrupt mask level (0 to

7). For details, refer to section 5, Interrupt Controller.

Operations can be performed on the EXR bits by the LDC, STC, ANDC, ORC, and XORC

instructions. All interrupts, including NMI, are disabled for three states after one of these

instructions is executed, except for STC.

(3) Condition-Code Register (CCR)

This 8-bit register contains internal CPU status information, including an interrupt mask bit (I) and

half-carry (H), negative (N), zero (Z), overflow (V), and carry (C) flags.

Bit 7—Interrupt Mask Bit (I): 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 by hardware at the start of an exception-

handling sequence. For details, refer to section 5, Interrupt Controller.

Bit 6—User Bit or Interrupt Mask Bit (UI): Can be written and read by software using the

LDC, STC, ANDC, ORC, and XORC instructions. With the H8S/2350 Group, this bit cannot be

used as an interrupt mask bit.

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 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.

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): Stores the value of the most significant bit (sign bit) of data.

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

HD6432351 датащи(PDF) 67 Page - Renesas Technology Corp