Texas Instruments TMS320C67X/C67X+ DSP manual 2. Interrupt Service Fetch Packet

Overview

5.1.2.1Interrupt Service Fetch Packet (ISFP)

An ISFP is a fetch packet used to service an interrupt. Figure 5−2 shows an ISFP that contains an interrupt service routine small enough to fit in a single fetch packet (FP). To branch back to the main program, the FP contains a branch to the interrupt return pointer instruction (B IRP). This is followed by a NOP 5 instruction to allow the branch target to reach the execution stage of the pipeline.

Note:

If the NOP 5 was not in the routine, the CPU would execute the next five execute packets that are associated with the next ISFP.

Figure 5−2. Interrupt Service Fetch Packet

ISFP for INT6

0C0h	Instr1
0C4h
	Instr2
0C8h
	Instr3
0CCh
	Instr4
0D0h
	Instr5
0D4h
	Instr6
0D8h
	B IRP
0DCh
	NOP 5

The interrupt service

routine for INT6 is short enough to be contained in a single fetch packet.

000h

020h

040h

060h

080h

0A0h

0C0h

0E0h

100h

120h

140h

160h

180h

1A0h

1C0h

1E0h

Interrupt service table

(IST)

RESET ISFP

NMI ISFP

Reserved

Reserved

INT4 ISFP

INT5 ISFP

INT6 ISFP

INT7 ISFP

INT8 ISFP

INT9 ISFP

INT10 ISFP

INT11 ISFP

INT12 ISFP

INT13 ISFP

INT14 ISFP

INT15 ISFP

Program memory

SPRU733 Interrupts 5-7