GNU Arm Embedded Toolchain

where is the source code for printf?

Asked by Doug Turnbow

I'm trying to debug an issue with printf() related to the heap.
If I have less than about 1k of heap declared, printf() seems to work fine, if I have more than 1k of heap it causes a variety of problems including resetting the processor.

I believe this is the call tree that my application is taking. Where would I find the source code to these functions?
printf()
_vfprintf_r()
__swsetup_r()
__smakebuf_r()
_isatty_r()
_isatty()
initialise_monitor_handles()

So I'm looking for the URL and filename that I would need to get in order to have this source code.

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Thomas Preud'homme
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Best Thomas Preud'homme (thomas-preudhomme) said : 		#1

Hi Doug,

You can find source code for these functions at [1] in files:

libc/stdio/vprintf.c
libc/stdio/swsetup.c
libc/stdio/makebuf.c
libc/posix/_isatty.c
libc/reent/isattyr.c

respectively.

[1] https://sourceware.org/viewvc/src/newlib/

Hope this helps you find the bug you are experiencing.

Best regards.

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Tony Liu (mrtoniliu) said : 		#2

Hi,

I would suggest you to look up these functions in the Newlib source code.
For example, you can find most of these functions located in the directory of <path to newlib source>/newlib/libc, e.g:
 "__swsetup_r()" in <path to newlib source>/libc/stdio/wsetup.c
 "initialise_monitor_handles()" in <path to newlib source>/newlib/libc/sys/arm/syscalls.c

Regards,
Tony

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Doug Turnbow (douglas-turnbow) said : 		#3

Thanks I'll take a look

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Doug Turnbow (douglas-turnbow) said : 		#4

Thanks Thomas Preud'homme, that solved my question.