C question - floating point initialization

Status
Not open for further replies.

LBdgWgt

Member level 5
Joined
Mar 6, 2006
Messages
83
Helped
5
Reputation
10
Reaction score
0
Trophy points
1,286
Activity points
2,066
Hello,

For example i have this type of union data:

typedef union {
unsigned long int my_long;
float my_float;
double my_double;
unsigned int my_word[2];
unsigned char my_byte[4];
} mydata;

how can i initialize a variable declared in mydata type with floating point value?
I am writing a code for HCS12 using ICC12
this code line doesn't work when i chek in the .lst file

mydata data1 = {1.25};

results in:

0404 _data::
0404 00000001 .word 0,1

is this the problem of the compiler or...?
thanks for any answer.
 

You would have to have a constant data variables in order to be able to initialize them.

Yuo need a const union in rom
 

actually this data will be implemented inside EEPROM (not Flash program memory), so i want to generate a floating point initialization value.

so what should i do?
 

If you put a value in the float variable in your union, all the variables in the union would get the same value.

You need a rom struct

const rom struct {
unsigned long int my_long;
float my_float;
double my_double;
unsigned int my_word[2];
unsigned char my_byte[4];
} mydata;

initialize all the variables to what you want.
bu you won't be able to change them in the code run time, they would be constant

Added after 5 minutes:

even a better way:

declare your structure first:

struct mydataStruct
{
unsigned long int my_long;
float my_float;
double my_double;
unsigned int my_word[2];
unsigned char my_byte[4];
}

then...

initialise it:

const rom struct mydataStruct mydata[5] = { put values here separated by a comma };
 

To initialize a variable declared in mydata type with floating point value you must use this:

mydata data1.my_float = 1.25;

Regards, svicent
 

svicent said:
To initialize a variable declared in mydata type with floating point value you must use this:

mydata data1.my_float = 1.25;

Regards, svicent
Click to expand...


That is not an initialization.
That is a statement.
 

In "The C programming language", you can read:

"A union may only be initialized with a value of the type of its first member. "

This code line works OK

mydata data1 = {1.25};

if you define:

typedef union {
float my_float;
unsigned long int my_long;
double my_double;
unsigned int my_word[2];
unsigned char my_byte[4];
} mydata;

Regards, svicent
 

    LBdgWgt

    Points: 2
    Helpful Answer Positive Rating
Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…