Technical Support

ARMCC: PRINTF OUTPUTS 0.000000 FOR FLOAT VARIABLES

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Information in this article applies to:

• RealView C Compiler Version 3
• RTX Real-Time Operating System

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QUESTION

I am using the RTX Kernel in my project. When I use printf (or a derivative such as sprintf, snprintf) in my source code together with float number, the only 0.000000 is printed.

What can be wrong?

ANSWER

This problem is caused by a mis-aligned stack (R13) register at the start of the task. It is important that the stack is 8-byte aligned.

Most likely you have an older version of the RTX_CONFIG.C file. Make sure that include a current version of the RTX_CONFIG.C file in your project.

Another reason for this problem might be that you have used the function os_tsk_create_user_ex or os_sys_init_user with an stack that is not 8-byte aligned.

MORE INFORMATION

• Refer to os_tsk_create_user in the RL-ARM User's Guide.
• Refer to os_tsk_create_user_ex in the RL-ARM User's Guide.
• Refer to os_sys_init_user in the RL-ARM User's Guide.

FORUM THREADS

The following Discussion Forum threads may provide information related to this topic.

• ARM RTX snprintf() floating point task.

Last Reviewed: Tuesday, December 11, 2007

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