Nios® V Processor Software Developer Handbook

ID 743810
Date 10/06/2025
Public
Document Table of Contents

7.7.6.5. Custom Logging Messages

You can add custom messages that are sent to the Altera® FPGA logging device. To define a custom message, include the header file alt_log_printf.h in your C source file as follows:

#include "sys/alt_log_printf.h"

Then use the following macro function:

ALT_LOG_PRINTF(const char *format, ...)

This C preprocessor macro invokes a pared-down version of printf(). The format argument supports most printf() options. It supports %c, %d, %I, %o, %s, %u, %x, and %X, as well as some precision and spacing modifiers, such as %-9.3o. It does not support floating point formats, such as %f or %g. This function is not compiled if Altera FPGA logging is not enabled.

If you want your custom logging message to be controlled by Altera FPGA logging preprocessor options, use the appropriate Altera FPGA logging option preprocessor flags from the Logging Levels table or the Altera FPGA Logging Options and Option Modifiers table.

Implementing Logging Options with Custom Logging Messages

/* The following example prints "Level 2 logging message" if
logging is set to level 2 or higher */
#if ( ALT_LOG_FLAGS >= 2 )
ALT_LOG_PRINTF ( "Level 2 logging message" );
#endif
/* The following example prints "Boot logging message" if boot logging
is turned on */
#if ( ALT_LOG_BOOT_ON_FLAG_SETTING == 1)
ALT_LOG_PRINTF ( "Boot logging message" );
#endif