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RX63T and s(n)printf with float or double
RX63T and s(n)printf with float or double
Hi,
Hi Everybody,
since a few days I´m trying to get a LCD running on my RX63T. Works fine for any type of variable but not for “float” or “double”. In this case the controller runs to nowhere.
Piece of my code:
extern int8_t Buffer[];
extern uint32_t value; // = 0xABCDEF
extern double pi; // = 3.141592
lcd_ddram_addr(FIRST_LINE,POS_0);
lcd_putc(‘0’);
lcd_putc(‘x’);
snprintf(Buffer,sizeof(Buffer),”%X”,value);
write_lcd(lcd_data, Buffer);
lcd_ddram_addr(SECOND_LINE,POS_0);
snprintf(Buffer,sizeof(Buffer),”%i”,value);
write_lcd(lcd_data, Buffer);
/*
lcd_ddram_addr(THIRD_LINE,POS_0);
snprintf(Buffer,sizeof(Buffer),”%0.6f”,pi);
write_lcd(lcd_data, Buffer);
*/
I´m working with e2 studio (Version: 5.1.0.022) and GNURX v16.01(ELF), so I hope that anybody can explain to me what I´m doign wrong.
Thank you in advance
Alex
Hello Alex,
Thank you for reaching GNU Support Team. We have tried to snprintf some values based on your code and succeeded.
First of all, we would like you to explain a little bit what does “runs to nowhere” mean.
Then we would like to comment the code excerpt you have sent.
1. sizeof(Buffer); //will result in error, as sizeof is compile-time evaluated, and Buffer being defined in another module(extern), there is no way to know the size of an incomplete type; you can explicitly define it as “extern int8_t Buffer[32];” instead
2. Please note, you can avoid consecutive calls of the same function (e.g. “lcd_putc(‘0’); lcd_putc(‘x’);”) by
a) allocating sufficient space in the Buffer variable and
b) printing the proper contents in the same Buffer variable, e.g. snprintf(Buffer, sizeof(Buffer), “0x%X”, value)
So, in order for a prompt and to the point answer, we would like to ask you to send your project to us for analysis.
—
Thank you,
Grigore Dobra,
The GNU Tools Team
-
AlexS. -
Hello Grigore,
Thanks a lot for your trouble.I have had changed from “newlib” to “optimized” and from “snprintf” to “sprintf” (without the sizeof(Buffer) argument) after that changes it runs perfectly.
With “runs to nowhere” I would like to say that the controller stops ecxecuting the code and does nothing anymore.1. What will be the expression of the error ? Because if I use “newlib” with snprintf(Buffer,sizeof(Buffer),”%X”,value); it works fine, for variable other than float or double.
2. Meanwhile I know, but later in project the complete LCD will be deleted, because in the moment it is just for testing and/or checking the calculated values.
Thank you, best regards
Alex -
Hello Alex,
We have made some tests in order to observe the behaviour reported by you but to no extent. Snprintf-ing or Sprintf-ing those values according to the correct format specifiers(format specifier matches variable type) works correctly. Anyway, using an “%x” format for float or double, for example won’t print the desired value, but its hexadecimal representation, that is 0x3f800000 for 1.0f. Moreover, this could shift other arguments because the size difference(4 bytes vs 8 bytes – int vs double), resulting in them to be displayed incorrectly.
As for your LCD being cleared, that cannot be because of snprintf/sprintf unless these functions output lots of spaces in the buffer instead of the desired values.
So we would like to ask you again to send in your project in order to have it analysed.
–-
Thank you,
Grigore Dobra,
The GNU Tools Team
