On Wed, Aug 26, 2009 at 4:02 PM, Randi Botse<nightdecoder@xxxxxxxxx> wrote: > Hi, I'm beginner C programmer, i have a problem, i want to store some > information in a integer, a integer will be 32 bit on my machine, i > want to have as follow: > > 6 bit (information 1) MSB > 4 bit (information 2) > 8 bit (information 3) > 5 bit (information 4) > 9 bit (information 5) LSB > > For example i set the informations as follow (in decimal): > > information 1 = 43 or 101011 > information 2 = 11 or 1011 > information 3 = 120 or 1111000 > information 3 = 30 or 11110 > information 4 = 418 or 110100010 > > if i join all informations i should get a 32 bit integer valued > 2935782212 or 01010111011111100011110110100010, then my problem is how > to retrieve these informations on bit operation? i want to know what's > the value of information-2 or information-3, etc directly. And, is > there any good way to join these informations to be an 32 bit integer? > > at this time i convert the 32bit integer into binary string, process > it's with array segment to get all informations then convert them to > integer, > to build the 32bit integer, i join all information value into binary > string (yes, 32 bit of char ;p) join all of them then convert to > integer. > > I know my way is sucks and too far away from COOL thing ;p, i think > there are cool way to do this!. > > Thanks before! > -- > To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > A quick, dirty way of doing it without structs: #include <stdio.h> void store_in_int( unsigned int *target, unsigned int offset, size_t field_sz, unsigned int value ) { unsigned int mask = ((1<<(field_sz))-1)<<offset; /* Clear field */ *target |= mask; *target ^= mask; /* Load field */ *target |= value<<offset; } unsigned int retrieve_from_int( unsigned int target, unsigned int offset, size_t field_sz ) { unsigned int mask = ((1<<(field_sz))-1); return (target>>offset)&mask; } int main ( void ) { unsigned int info=0; store_in_int(&info, 0, 6, 43); store_in_int(&info, 6, 4, 11); store_in_int(&info,10, 8,120); store_in_int(&info,18, 5, 30); store_in_int(&info,23, 9,418); printf("info1: %u\n",retrieve_from_int( info, 0, 6 )); printf("info2: %u\n",retrieve_from_int( info, 6, 4 )); printf("info3: %u\n",retrieve_from_int( info,10, 8 )); printf("info4: %u\n",retrieve_from_int( info,18, 5 )); printf("info5: %u\n",retrieve_from_int( info,23, 9 )); return 0; } -- To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
