dsp56800e Freescale Semiconductor, Inc, dsp56800e Datasheet - Page 599

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

RTI
Operation:
X:(SP) → SR
SP – 1→ SP
SR[14:10],X:(SP) → PC
SP – 1→ SP
Description: Return to normal execution at the end of an interrupt service routine. The return restores the status reg-
Example:
Explanation of Example:
Restrictions:
Condition Codes Affected:
Instruction Fields:
Instruction Opcodes:
Timing:
Memory:
Freescale Semiconductor
RTI
Operation
RTI
SP
ister (SR) and program counter (PC) from the software stack. The previous PC is lost, and execution
resumes at the address 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.
RTI
The RTI 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.
All bits are set according to the value removed from the stack
8 oscillator clock cycles
1 program word
Before Execution
X:$0101
X:$0100
LF
15
Operands
SR
P4
14
000101
13
P3
P2
12
754C
1008
0219
MR
P1
11
; pull the SR and PC registers from the stack
Return from Interrupt
C
8
15
P0
1
10
Instruction Set Details
W
1
1
I1
9
Return from interrupt, restoring 21-bit PC and SR from the stack
1
Assembler Syntax:
RTI
I0
8
12
0
SZ
7
11
0
6
L
1
SP
5
E
After Execution
X:$0101
X:$0100
1
U
4
CCR
1
8
SR
Comments
N
3
7
0
0000FF
0
2
Z
754C
1008
1008
0
V
1
0
4
C
0
1
3
0
0
RTI
A-255
1
0