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ColdFire Core
MCF5272 ColdFire
®
Integrated Microprocessor User’s Manual, Rev. 3
2-6
Freescale Semiconductor
from the reset exception vector, address 0x0000. The same register is used for user and supervisor modes,
and may be used for word and longword operations.
A subroutine call saves the program counter (PC) on the stack and the return restores the PC from the stack.
The PC and the status register (SR) are saved on the stack during exception and interrupt processing. The
return from exception instruction restores SR and PC values from the stack.
2.2.1.4
Program Counter (PC)
The PC holds the address of the executing instruction. For sequential instructions, the processor
automatically increments the PC. When program flow changes, the PC is updated with the target
instruction. For some instructions, the PC specifies the base address for PC-relative operand addressing
modes.
2.2.1.5
Condition Code Register (CCR)
, occupies SR[7–0], as shown in
. CCR[4–0] are indicator flags based on
results generated by arithmetic operations.
7
6
5
4
3
2
1
0
Field
—
X
N
Z
V
C
Reset
000
Undefined
R/W
R
R/W
R/W
R/W
R/W
R/W
Figure 2-4. Condition Code Register (CCR)
Table 2-1. CCR Field Descriptions
Bits
Name
Description
7–5
—
Reserved, should be cleared.
4
X
Extend condition code bit. Assigned the value of the carry bit for arithmetic operations; otherwise not
affected or set to a specified result. Also used as an input operand for multiple-precision arithmetic.
3
N
Negative condition code bit. Set if the msb of the result is set; otherwise cleared.
2
Z
Zero condition code bit. Set if the result equals zero; otherwise cleared.
1
V
Overflow condition code bit. Set if an arithmetic overflow occurs, implying that the result cannot be
represented in the operand size; otherwise cleared.
0
C
Carry condition code bit. Set if a carry-out of the data operand msb occurs for an addition or if a borrow
occurs in a subtraction; otherwise cleared.