dsp56800e Freescale Semiconductor, Inc, dsp56800e Datasheet - Page 600

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

RTID
Operation:
X:(SP) → SR
SP – 1→ SP
SR[14:10],X:(SP) → PC
SP – 1→ SP
Execute instructions in next 3 delay slots
Description: Return to normal execution at the end of an interrupt service routine, but execute the instructions in the
Example:
Explanation of Example:
Restrictions:
Condition Codes Affected:
A-256
SP
next 3 words of the instruction before returning. The return restores the status register (SR) and pro-
gram counter (PC) from the software stack. The previous PC is lost, and execution resumes at the ad-
dress that is indicated by the (restored) PC. Bits 10 through 14 of the SR contain the upper 5 bits of the
original PC at the time of the interrupt.
OTHERCODE
The RTID instruction pulls the 16-bit PC and the 16-bit SR from the stack and updates the system SP.
Program execution continues at $04754C (PC bits 16–20 are obtained from bits 10–14 of the restored
status register). The example shows a level 1 interrupt source.
Refer to Section 10.4, “Pipeline Dependencies and Interlocks,” on page 10-26.
Refer to Section 4.3.2, “Delayed Instruction Restrictions,” on page 4-14.
All set according to value removed from stack
Before Execution
X:$0101
X:$0100
LF
15
SR
P4
14
RTID
BFTSTH
NOP
...
000101
13
P3
Delayed Return from Interrupt
P2
12
754C
1108
0214
MR
DSP56800E Core Reference Manual
P1
11
#$8001,A1
P0
10
I1
9
Assembler Syntax:
RTID
I0
8
SZ
7
6
L
; return from ISR
; first 2 delay slots
; last delay slot (unused)
SP
5
E
After Execution
X:$0101
X:$0100
U
4
CCR
SR
N
3
0000FF
2
Z
754C
1108
1108
Freescale Semiconductor
V
1
C
0
RTID