dsp56800e Freescale Semiconductor, Inc, dsp56800e Datasheet - Page 251

• Manufacturer Part Number: dsp56800e
• Description: 16-bit Digital Signal Controller Core
• Manufacturer: Freescale Semiconductor, Inc

The FISR holds copies of the status register’s LF, I1, I0, SZ, L, E, U, N, Z, V, and C bits as well as the
operating mode register’s NL bit. The SPL bit holds a copy of the LSB of the stack pointer (SP), which
allows the stack pointer to be restored to its original value after interrupt processing is complete. See
Section 9.3.2.2, “Fast Interrupt Processing,” on page 9-6 for more information on fast interrupt processing
and on the use of the FISR register. This register is not affected by processor reset.
FISR
Freescale Semiconductor
Undefined
Bits 15–13
SPL
Bit 12
LF
Bit 11
NL
Bit 10
I1–I0
Bits 9–8
SZ
Bit 7
L
Bit 6
E
Bit 5
U
Bit 4
N
Bit 3
Z
Bit 2
V
Bit 1
C
Bit 0
TYPE
Name
BIT 15
Undefined
Stack Pointer LSB—Contains a copy of the
LSB of the SP register
Loop Flag—Contains a copy of the LF bit in the
status register
Nested Looping—Contains a copy of the NL bit
in the operating mode register
Interrupt Mask—Contains a copy of the I1 and
I0 bits in the status register
Size—Contains a copy of the SZ bit in the status
register
Limit—Contains a copy of the L bit in the status
register
Extension in Use—Contains a copy of the E bit
in the status register
Unnormalized—Contains a copy of the U bit in
the status register
Negative—Contains a copy of the N bit in the
status register
Zero—Contains a copy of the Z bit in the status
register
Overflow—Contains a copy of the V bit in the
status register
Carry—Contains a copy of the C bit in the status
register
14
13
SPL
12
rw
Description
Fast Interrupt Status Register
11
LF
rw
Table 8-4. FISR Bit Descriptions
NL
10
rw
Program Controller
rw
I1
9
rw
I0
8
SZ
rw
7
Value in stack pointer on interrupt.
Value in status register on interrupt.
Value in operating mode register on interrupt.
Value in status register on interrupt.
Value in status register on interrupt.
Value in status register on interrupt.
Value in status register on interrupt.
Value in status register on interrupt.
Value in status register on interrupt.
Value in status register on interrupt.
Value in status register on interrupt.
Value in status register on interrupt.
These bits are undefined and should be ignored.
Program Controller Programming Model
rw
6
L
rw
E
5
rw
U
4
Settings
rw
N
3
rw
2
Z
rw
V
1
BIT 0
8-13
rw
C