User guide

GUI Reference
ISS Settings Tab (Run/Debug Dialog Box)
You open this tab by clicking the ISS Settings tab on the Run/Debug dialog box for
Nios II Instruction Set Simulator configurations.
The ISS Settings tab allows you to configure settings specific to the Nios II instruction set
simulator (ISS). Most settings on this tab are grouped by category.
Trace Options
The following options control how much trace information the ISS reports.
Enable Tracing—Enables tracing the instruction-by-instruction execution of the
processor in simulation. The trace information output depends on the remaining trace
options.
Information—Outputs information about the system and debugging process.
Disassembly—Outputs the program counter, assembly instructions, and values of
affected registers.
Registers—Outputs the processor registers. Registers include the program counter
(PC), r0, at(r1), r2-r23, et, bt, gp, sp, fp, ea, ba, ra, status,
estatus, bstatus, ienable, and ipending.
Warning—Outputs ISS warnings encountered while simulating.
Instruction Count —Outputs the instruction number of the currently executing
instruction. This option only has an effect if the Disassembly or Registers options
are on.
Send trace output to file—When on, the ISS writes trace output to the specified file.
o Trace File—Specifies where to save trace data. This uses the application
project directory if you do not specify a different location.
Start tracing from —Specifies the trace entry-point function. The choices are:
main(), alt_main() or the program entry point. This setting defaults to main(), which
allows you to ignore any pre-main() activity. Note that from the program entry point
to the start of main() or alt_main(), as many as several hundred thousand
instructions occur.
Host Communications Devices
The following options control where the ISS directs the stdio, stdout, and stderr character
streams.
Use default host communication devices—When on, the ISS uses the
communication devices specified in the Nios II system library project. You can turn
this setting off to manually select the host communication device for stdio, stdout, and
stderr. The ISS settings for stdio, stdout, and stderr override the system library
project settings.
stdout— Specifies the communication device for stdout.
stderr— Specifies the communication device for stderr.
stdin— Specifies the communication device for stdin.
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