1 /** 2 *文件：bit.h 3 *目的: 实现bitmap数据结构 4 *作者：杜小波 5 *联系方式：code2living@gmail.com 6 **/ 7 8 #ifndef _BIT_H_ 9 #define _BIT_H_ 10 11 /** 12 *存储bitmap的结构体 13 *存储的顺序从左至右 14 **/ 15 struct _Bits; 16 typedef struct _Bits *bits; 17 18 /** 19 *获得bitmap 20 *@length bitmap的长度 21 *@return 所有位都初始化为0的bitmap 22 */ 23 bits bit_new(unsigned int length); 24 25 /** 26 *销毁一个bitmap 27 **/ 28 void bit_destroy(bits bit); 29 30 /** 31 *获得y一个bitmap的长度 32 *@bit 需要获得长度的bitmap 33 *@return bit的长度 34 **/ 35 unsigned int bit_length(bits bit); 36 37 /** 38 *设置bitmap中相应位置的值 39 *@bit 待设置的bitmap 40 *@pos 需要设置的位置 41 **/ 42 void bit_set(bits bit, unsigned int pos, unsigned char value); 43 44 /** 45 *设置bitmap中相应位置的值 46 *@bit 待获取的bitmap 47 *@pos 获取的位置 48 **/ 49 char bit_get(bits bit, unsigned int pos); 50 51 #endif /*_BITS_H_*/
#include "bit.h" #include <stdio.h> #include <stdlib.h> #include <string.h> struct _Bits { char *bits; unsigned int length; }; bits bit_new(unsigned int length) { bits new_bits = (bits)malloc(sizeof(struct _Bits)); if (new_bits == NULL) return NULL; int char_nums = sizeof(char) * (length >> 3) + 1; new_bits->bits = (char *)malloc(char_nums); if (new_bits == NULL) { free(new_bits); return NULL; } memset(new_bits->bits, 0, char_nums); new_bits->length = length; return new_bits; } void bit_destroy(bits bit) { free(bit->bits); free(bit); } unsigned int bit_length(bits bit) { return bit->length; } void bit_set(bits bit, unsigned int pos, unsigned char value) { unsigned char mask = 0x80 >> (pos & 0x7); if (value) { bit->bits[pos>>3] |= mask; } else { bit->bits[pos>>3] &= ~mask; } } char bit_get(bits bit, unsigned int pos) { unsigned char mask = 0x80 >> (pos & 0x7); return (mask & bit->bits[pos>>3]) == mask ? 1 : 0; }
1 #include <stdio.h> 2 #include "bit.h" 3 #define LEN 15 4 int main(void) 5 { 6 bits bit = bit_new(LEN); 7 8 printf("length: %u\n", bit_length(bit)); 9 10 unsigned int test_value = 0x735D; 11 unsigned char value; 12 int i; 13 for (i = LEN - 1; i >= 0; i--) { 14 value = test_value & 1; 15 bit_set(bit, i, value); 16 test_value >>= 1; 17 } 18 19 for (i = 0; i < LEN; i++) { 20 printf("%d", bit_get(bit, i)); 21 } 22 printf("\n"); 23 24 bit_destroy(bit); 25 26 return 0; 27 }
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