AT697F_14 datasheet(21/176 Pages) ATMEL

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AT697F

7703E–AERO–08/11

Traps and Interrupts

Overview

The AT697F supports two types of traps:

•

synchronous traps

•

asynchronous traps also called interrupts.

Synchronous traps are caused by the hardware responding to a particular instruction.

They occur during the instruction that caused them. Asynchronous traps occur when an

external event interrupts the processor. They are not related to any particular instruction

and occur between the execution of instructions.

A trap is a vectored transfer of control to the supervisor through a special trap table that

contains the first four instructions of each trap handler. The trap base address (TBR) of

the table is established by the supervisor and the displacement, within the table, is

determined by the trap type.

A trap causes the current window pointer to advance to the next register window and the

hardware to write the program counters (PC & nPC) into two registers of the new

window.

Synchronous Traps

The AT697F follows the general SPARC trap model. The table below shows the imple-

mented traps and their individual priority.

Table 4. Trap Overview

Trap

Trap Type

Priority

Description

reset

n/a(1)

Power-on reset

write_error

0x2B

Write buffer error

instruction_access_exception

0x01

Error during instruction fetch

Edac uncorrectable error during instruction

fetch

illegal_instruction

0x02

UNIMP or other un-implemented

instruction

privileged_instruction

0x03

Execution of privileged instruction in user

mode

fp_disabled

0x04

FP instruction while FPU disabled

cp_disabled

0x24

Co-processor instruction while co-

processor disabled

watchpoint_detected

0x0B

Instruction or data watchpoint match

window_overflow

0x05

SAVE into invalid window

window_underflow

0x06

RESTORE into invalid window

register_hardware_error

0x20

mem_address_not_aligned

0x07

Memory access to un-aligned address

fp_exception

0x08

FPU exception

data_access_exception

0x09

Access error during load or store

instruction

tag overflow

0x0A

Tagged arithmetic overflow

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