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ljbeng
Joined: 10 Feb 2004
Posts: 205
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| Should be simple, convert 4 bytes to float32 |
 Posted: Tue Nov 03, 2009 5:23 pm |
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| With the pcwhd 4.096 and PIC24F, my float32 should be IEEE format, 4 bytes, correct? I have the 4 hex bytes in an eeprom and I need to convert the bytes to float. What is the command for this? Thanks. |
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FvM
Joined: 27 Aug 2008
Posts: 2337
Location: Germany
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| Posted: Tue Nov 03, 2009 5:29 pm |
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| It's no actual conversion, just a copy. You can use make32() built in function to combine the bytes. If I remember right, PCD is using IEEE float with reversed byte order. |
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ljbeng
Joined: 10 Feb 2004
Posts: 205
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| Posted: Wed Nov 04, 2009 8:46 am |
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Ok, I get it....
| Code: |
float readfile(int16 srval){
float rtval;
pathval[0] = read_ext_eeprom(srval);
pathval[1] = read_ext_eeprom(srval + 1);
pathval[2] = read_ext_eeprom(srval + 2);
pathval[3] = read_ext_eeprom(srval + 3);
pathv = make32(pathval[3],pathval[2],pathval[1],pathval[0]);
memcpy(&rtval,&pathv,4);
return rtval;
}
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FvM
Joined: 27 Aug 2008
Posts: 2337
Location: Germany
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| Posted: Wed Nov 04, 2009 9:34 am |
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Yes, basically correct, but:
| Code: | float readfile(int16 srval){
union {
float rtval;
int8 pathval[4];
}u;
u.pathval[0] = read_ext_eeprom(srval);
u.pathval[1] = read_ext_eeprom(srval + 1);
u.pathval[2] = read_ext_eeprom(srval + 2);
u.pathval[3] = read_ext_eeprom(srval + 3);
// Two copy actions can be saved
//pathv = make32(pathval[3],pathval[2],pathval[1],pathval[0]);
//memcpy(&rtval,&pathv,4);
return u.rtval;
} |
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