2008년 03월 19일
2008년 1학기 시스템 프로그래밍 - Little Endian vs. Big Endian
2008년 1학기 시스템 프로그래밍 과제
2. Little Endian vs. Big Endian
Write a C program to test
whether it is running on a big endian or little endian architecture.
union을 이용하여 Endian의 영향을 받는 long int와
그렇지 않은 string으로 확인하였습니다.
코드
/*
* Check_Machine_Endian (Little Endian vs. Big Endian)
*
* This function check the machine's Endian.
*
* - Argument
* void
*
* - Return
* void
*
*
* I use union.
* union is shared memory in its variables.
* Therefore I set unsigned long int variable and array of char variables that size is same unsigned long int.
* and I set number 1 at unsigned long int variable.
* So If this machine use Little Endian, then 1 is in lowest address in unsigned long int.
* Hence array of char's fisrt element is set 1.
* But If this machine use Big Endian, then 1 is in highest address in unsigned long int.
* Hence array of char's first element is set 0.
* If both 0 and 1 are not, then I don't know.
*
*
* <- low address high ->
* Big Endian
* 00 | 00 | 00 | 01
*
* Little Endian
* 01 | 00 | 00 | 00
*
*
* Made by Bak JinYeong, 2008.03.13*/
void Check_Machine_Endian(void)
{
typedef union
{
unsigned long int word_size_int; // unsigned long int : machine word size
unsigned char word_size_char_arr[sizeof(long int)]; // char(1byte) array that size is size of long int. Therefore It is same size of variable i.
} word_size_int_char_u; // union name is word_size_int_char_u
word_size_int_char_u int_char_union; // make the variable int_char_union. int_char_union's type is word_size_int_char_u
int_char_union.word_size_int = 1; // set value 1 at sord_size_int in int_char_union
if(1 == int_char_union.word_size_char_arr[0]) // if this machine use Little Endian,
{
printf("This machine is Little Endian\n"); // then 1 is in lowest address in unsigned long int.
}
else if(0 == int_char_union.word_size_char_arr[0]) // if this machine use Big Endian,
{
printf("This machine is Big Endian\n"); // then 1 is in highest address in unsigned long int.
}
else
{
printf("I don't know, what Endian this machine use.\n"); // I don't know what Endian
}
}
# by | 2008/03/19 20:09 | in Lesson | 트랙백 | 핑백(1) | 덧글(0)
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