H8SSLASH2218 datasheet(90/750 Pages) RENESAS

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Section 2 CPU

Rev.6.00 Jun. 03, 2008 Page 42 of 698

REJ09B0074-0600

2.4.4

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.

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

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

(Bcc) instructions.

Bit

Bit Name

Initial Value

R/W Description

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

by hardware at the start of an exception-handling

sequence. For details, refer to section 5, Interrupt

Controller.

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R/W User Bit or Interrupt Mask Bit

Can be written and read by software using the LDC, STC,

ANDC, ORC, and XORC instructions. This bit cannot be

used as an interrupt mask bit in this LSI.

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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.

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R/W User Bit

Can be written and read by software using the LDC, STC,

ANDC, ORC, and XORC instructions.

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R/W Negative Flag

Stores the value of the most significant bit of data as a sign

bit.

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R/W Zero Flag

Set to 1 to indicate zero data, and cleared to 0 to indicate

non-zero data.

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