Author Topic: Weird error: sprintf  (Read 6621 times)

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Offline Vogtinator

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Weird error: sprintf
« on: December 24, 2012, 12:11:58 pm »
I was just fiddling with some sine and cosine tables and needed some debugging.
But the output was always "0.00000". I tried to execute
Code: [Select]
float oneandahalf = 1.5f;
double twoandahalf = 2.5;
int one = 1;
char str[60];
sprintf(str, "1.5: %f 2.5: %f 1: %d", oneandahalf, twoandahalf, one);
show_msgbox(str, str);
It compiles fine, result:

Dafuq is going on there :o
Same result with nspire_emu.

Offline epic7

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Re: Weird error: sprintf
« Reply #1 on: December 24, 2012, 12:40:58 pm »
Lolwut? O.O
I was trying to debug float values too, and was also getting a similar wierd problem D:

Offline Ranman

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Re: Weird error: sprintf
« Reply #2 on: December 24, 2012, 12:52:34 pm »
See if this works:

sprintf(str, "1.5: %f 2.5: %f 1: %d", 1.5, 2.5, 1);

It may at the very least narrow down the bug.
« Last Edit: December 24, 2012, 12:53:35 pm by Ranman »
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Offline Vogtinator

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Re: Weird error: sprintf
« Reply #3 on: December 24, 2012, 01:05:00 pm »
Nope, no change.

Code: [Select]
sprintf(str, "1: %d 2.5: %f 1.5: %f", 1, 2.5f, 1.5);prints: "1: 1 1.5: 0.000000 2.5: 0.000000".
Seems to be some kind of issue with va_list's and aligning, doesn't it?
« Last Edit: December 24, 2012, 01:06:03 pm by Vogtinator »

Offline Ranman

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Re: Weird error: sprintf
« Reply #4 on: December 24, 2012, 01:13:19 pm »
Nope, no change.

Code: [Select]
sprintf(str, "1: %d 2.5: %f 1.5: %f", 1, 2.5f, 1.5);prints: "1: 1 1.5: 0.000000 2.5: 0.000000".
Seems to be some kind of issue with va_list's and aligning, doesn't it?

Yeah... looks like something is wrong with sprintf itself or some type of alignment issue.

You should report the bug and give the examples that you posted here.
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Offline Vogtinator

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Re: Weird error: sprintf
« Reply #5 on: December 24, 2012, 01:20:57 pm »
http://www.unsads.com/projects/nsptools/register
Can't register..
Do I have to mail him?

Offline Lionel Debroux

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Re: Weird error: sprintf
« Reply #6 on: December 24, 2012, 02:37:57 pm »
Maybe GCC and Nucleus / TI's code use different formats for floating-point values ?
(at least, TI's Lua and C do)
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Offline calc84maniac

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Re: Weird error: sprintf
« Reply #7 on: December 24, 2012, 03:12:55 pm »
You're passing a double to a %f specifier, that's a problem don't you think? Make it %lf for the double.
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Offline Vogtinator

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Re: Weird error: sprintf
« Reply #8 on: December 24, 2012, 04:39:21 pm »
Tried that, doesn't work.
But it shouldn't confuse va_list.

Code: [Select]
sprintf(str, "%d, %f, %lf", 1, 1.5f, 2.5);Should be fine I think.

Quote
Maybe GCC and Nucleus / TI's code use different formats for floating-point values ?
Is sprintf a syscall? Isn't it included in newlib?

Edit:
Gcc thinks "1.5f" is a double..
« Last Edit: December 24, 2012, 05:03:03 pm by Vogtinator »

Offline lkj

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Re: Weird error: sprintf
« Reply #9 on: December 24, 2012, 05:17:10 pm »
Quote
Maybe GCC and Nucleus / TI's code use different formats for floating-point values ?
Is sprintf a syscall? Isn't it included in newlib?
sprintf is a syscall, yes. Ndless almost only uses syscalls and AFAIK doesn't use Newlib.
« Last Edit: December 24, 2012, 05:17:45 pm by lkj »

Offline Vogtinator

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Re: Weird error: sprintf
« Reply #10 on: December 24, 2012, 05:26:53 pm »
Quote
sprintf is a syscall, yes. Ndless almost only uses syscalls and AFAIK doesn't use Newlib.
http://hackspire.unsads.com/wiki/index.php/C_and_assembly_development_introduction_on_Linux
But it gets build and gcc links against it.
« Last Edit: December 24, 2012, 05:27:12 pm by Vogtinator »

Offline lkj

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Re: Weird error: sprintf
« Reply #11 on: December 24, 2012, 06:05:21 pm »
http://hackspire.unsads.com/wiki/index.php/Syscalls says Newlib is used for exit() and here it says it's also used for floating point (because there's no FPU). But most other parts of newlib don't work with Ndless.
« Last Edit: December 24, 2012, 06:05:35 pm by lkj »

Offline Vogtinator

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Re: Weird error: sprintf
« Reply #12 on: December 24, 2012, 06:09:15 pm »
Wouldn't it be better to provide it directly with newlib?
It would be faster and there will be no such problems anymore.
Only disadvantage would be the increasing size of the binary.

Edit: Workaround: Use http://stackoverflow.com/questions/2302969/how-to-implement-char-ftoafloat-num-without-sprintf-library-function-i.
The third answer works perfectly with floats, too.
« Last Edit: December 25, 2012, 08:35:37 am by Vogtinator »