Renesas H8SX/1650, Руководство по оборудованию

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Section 2 CPU
Rev.2.00 Jun. 28, 2007 Page 27 of 666
REJ09B0311-0200
Bit Bit Name
Initial
Value R/W
Description
5 H 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.
4 U Undefined R/W User Bit
Can be written and read by software using the LDC,
STC, ANDC, ORC, and XORC instructions.
3 N Undefined R/W Negative Flag
Stores the value of the most significant bit (regarded as
sign bit) of data.
2 Z Undefined R/W Zero Flag
Set to 1 to indicate zero data, and cleared to 0 to
indicate non-zero data.
1 V Undefined R/W Overflow Flag
Set to 1 when an arithmetic overflow occurs, and
cleared to 0 otherwise.
0 C Undefined R/W Carry Flag
Set to 1 when a carry occurs, and cleared to 0
otherwise. A carry flag indicates the following:
•
A carry by an add instruction
•
A borrow by a subtract instruction
•
A carry by a shift or rotate instruction
The carry flag is also used as a bit accumulator by bit
manipulation instructions.