1. #include <stdio.h>
    2. typedef unsigned char byte;
    3. typedef byte BIT8;
    4. typedef unsigned char * MEMCUR;
    5. int isEndianMode();
    6. void memory_layout(MEMCUR start, int len){
    7.     char *binStr[16] = {
    8.         "0000","0001",
    9.         "0010","0011",
    10.         "0100","0101",
    11.         "0110","0111",
    12.         "1000","1001",
    13.         "1010","1011",
    14.         "1100","1101",
    15.         "1110","1111"
    16.     };
    17.     if(!len) len=sizeof(MEMCUR*);
    18.     MEMCUR cur = start;
    19.     int iter;
    20.     int AL,AH;
    22.     if(!isEndianMode()){
    23.         cur = start+3;
    24.         for(iter = 0; iter < len;iter++,cur--){
    25.             AL = *cur & 0b00001111;
    26.             AH = *cur >> 4; 
    27.             printf("%p %s %s %.2X\n",cur,binStr[AH], binStr[AL], *cur);
    28.         }
    29.     }else{
    30.         for(iter = 0; iter < len;iter++,cur++){
    31.             AL = *cur & 0b00001111;
    32.             AH = *cur >> 4; 
    33.             printf("%p %s %s %.2X\n",cur,binStr[AH], binStr[AL], *cur);
    34.         }
    35.     }
    37. }
    40. int isEndianMode(){
    41.   unsigned char *cursor;            //单字节的游标指针
    42.   unsigned short num = 0xff00;      //储存两个字节的数
    43.   cursor = (unsigned char *)&num;   //进行类型转换
    44.   if (*cursor < *(cursor + 1))      //如果高地址值更大
    45.     return 0;
    46.   else return 1;
    47. }
    48. /*
    49. value = sign * exp * frac
    50. V = (-1)^s * M * 2^E
    51. E = e - bias
    52. bias = 127(m32)
    53. bias = 1023(m64)
    54. e bias E 2^E f m value
    55. NaN not a number
    56. inf infinte
    57. */
    58. int main(){
    59.     int te = 0xABCDEF12;
    60.     memory_layout((MEMCUR)&te,4);
    61.     float x = -1;
    62.     printf("sizeof x in m64 is %d\n", sizeof(x));
    63.     printf("%f\n",x);
    64.     printf("%p\n",&x);
    65.     memory_layout((MEMCUR)&x,4);
    66.     x = 1;
    67.     printf("---------\n");
    68.     memory_layout((MEMCUR)&x,4);
    69.     printf("%f\n",x);
    70.     x = 0.5;
    71.     printf("---------\n");
    72.     memory_layout((MEMCUR)&x,4);
    73.     printf("%f\n",x);
    74.     x = 0.25;
    75.     printf("---------\n");
    76.     memory_layout((MEMCUR)&x,4);
    77.     printf("%f\n",x);
    78.     return 0;
    79. }
    80. /*
    82. 0011 1111 3F
    83. 1110 0000 E0
    84. 0001 0101 15
    85. 0001 0111 17
    88. 1011 1111 BF
    89. 1110 0000 E0
    90. 0001 0101 15
    91. 0001 0111 17
    93. */