R01UH0823EJ0100 Rev.1.00
Page 73 of 1823
Jul 31, 2019
RX23W Group
2. CPU
2.2.2.5
Processor Status Word (PSW)
Note 1. In user mode, writing to the IPL[3:0], PM, U, and I bits by an MVTC or a POPC instruction is ignored. Writing to the IPL[3:0] bits
by an MVTIPL instruction generates a privileged instruction exception.
Note 2. In supervisor mode, writing to the PM bit by an MVTC or a POPC instruction is ignored, but writing to the other bits is possible.
Note 3. Switching from supervisor mode to user mode requires execution of an RTE instruction after having set the
PSW.PM bit
saved
on the stack to 1 or executing an RTFI instruction after having set the
BPSW.PM bit
to 1.
The processor status word (PSW) indicates the results of instruction execution or the state of the CPU.
b31
b30
b29
b28
b27
b26
b25
b24
b23
b22
b21
b20
b19
b18
b17
b16
—
—
—
—
IPL[3:0]
—
—
—
PM
—
—
U
I
Value after reset:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
b15
b14
b13
b12
b11
b10
b9
b8
b7
b6
b5
b4
b3
b2
b1
b0
—
—
—
—
—
—
—
—
—
—
—
—
O
S
Z
C
Value after reset:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
Symbol
Bit Name
Description
R/W
b0
Carry Flag
0: No carry has occurred.
1: A carry has occurred.
R/W
b1
Zero Flag
0: Result is non-zero.
1: Result is 0.
R/W
b2
Sign Flag
0: Result is a positive value or 0.
1: Result is a negative value.
R/W
b3
Overflow Flag
0: No overflow has occurred.
1: An overflow has occurred.
R/W
b15 to b4
—
Reserved
These bits are read as 0. The write value should be 0.
R/W
b16
Interrupt Enable
0: Interrupt disabled.
1: Interrupt enabled.
R/W
b17
Stack Pointer Select
0: Interrupt stack pointer (ISP) is selected.
1: User stack pointer (USP) is selected.
R/W
b19, b18
—
Reserved
These bits are read as 0. The write value should be 0.
R/W
b20
Processor Mode Select
0: Supervisor mode is selected.
1: User mode is selected.
R/W
b23 to b21 —
Reserved
These bits are read as 0. The write value should be 0.
R/W
b27 to b24 IPL[3:0]*
Processor Interrupt Priority Level
b27
b24
0 0 0 0: Priority level 0 (lowest)
0 0 0 1: Priority level 1
0 0 1 0: Priority level 2
0 0 1 1: Priority level 3
0 1 0 0: Priority level 4
0 1 0 1: Priority level 5
0 1 1 0: Priority level 6
0 1 1 1: Priority level 7
1 0 0 0: Priority level 8
1 0 0 1: Priority level 9
1 0 1 0: Priority level 10
1 0 1 1: Priority level 11
1 1 0 0: Priority level 12
1 1 0 1: Priority level 13
1 1 1 0: Priority level 14
1 1 1 1: Priority level 15 (highest)
R/W
b31 to b28 —
Reserved
These bits are read as 0. The write value should be 0.
R/W