cutil-bit7.c

Linux环境下常用功能的实现

#include "cutil.h"

/**
 * cutil_bit7_from_bit8
 * @bit8: 要转换的英文字符串
 * @olen: 转换后的字符串长度
 *
 * 转换的BIT8到BIT7
 *
 * Returns: 新分配的空间
 */
char * cutil_bit7_from_bit8(char *bit8, int *olen)
{
	int i,j;
	char bitmap,next_bit,bit;
	int len = strlen(bit8);
	char *bit7 = (char *)calloc(len/8 * 7 + 2, sizeof(char));
	
	memset(bit7, 0, len/8 * 7 + 2);
	bitmap = 0x01;
	bit = 0;
	for( i = 0,j=0  ; i < len ; i ++,j++)
	{
		next_bit = bit8[i+1] & bitmap;
		bit7[j] = ( bit8[i] >> bit) | (next_bit << ( 7 - bit)); 
		bit ++;
		if(bit == 7)
		{
			bit = 0;
			bitmap = 0x01;
			i ++;
		}
		else
		{
			bitmap = (bitmap << 1) | 0x01;
		}
	}
	if(olen)
		*olen = j;
	return bit7;
}

/**
 * cutil_bit7_to_bit8
 * @bit7: 要转换的英文字符串
 * @olen: 转换后的字符串长度
 *
 * 转换的BIT7到BIT8
 *
 * Returns: 新分配的空间
 */
char * cutil_bit7_to_bit8(char *bit7, int *olen)
{
	int i ,j ;
	unsigned char bitmap,back_bit,old_bit,bit;
	int len = strlen(bit7);
	char *bit8 = (char *)calloc(len / 7 * 8 + 2, sizeof(char));

	memset(bit8, 0, len / 7 * 8 + 2);

	bitmap = 0x80;
	bit = 0 ;
	old_bit = 0;
	for( i = 0 ,j = 0 ; i < len ; i ++,j++)
	{
		back_bit = bit7[i] & bitmap;
		bit8[j] =  old_bit| ((bit7[i] & (~bitmap)) << bit);
		old_bit = back_bit >> (7 - bit);
		bit ++;
		if(bit == 7)
		{
			j ++;
			bit8[j] = old_bit;
			old_bit = 0;
			bitmap = 0x80;
			bit = 0;
		}
		else
		{
			bitmap = (bitmap >> 1 ) | 0x80;
		}
	}
	if(olen)
		*olen = j;
	return bit8;
}

/**
 * cutil_bit7_hex_str_from_bit8
 * @bit8: 要转换的英文字符串
 * @olen: 转换后的字符串长度
 *
 * 转换的BIT8到十六进制打印BIT7
 *
 * Returns: 新分配的空间
 */
char * cutil_bit7_hex_str_from_bit8(char *bit8, int * olen)
{
	char *s;
	int len;
	char *p;

	s = cutil_bit7_from_bit8(bit8, &len);
	p = cutil_string_to_hex(s, len, olen);
	free(s);
	return p;
}

/**
 * cutil_bit7_hex_str_to_bit8
 * @bit7_hex: 要转换的英文字符串
 * @olen: 转换后的字符串长度
 *
 * 转换的BIT8从十六进制打印BIT7
 *
 * Returns: 新分配的空间
 */
char * cutil_bit7_hex_str_to_bit8(char *bit7_hex, int * olen)
{
	char *s;
	char *p;

	s = cutil_string_from_hex(bit7_hex, NULL);
	p = cutil_bit7_to_bit8(s, olen);
	free(s);
	return p;
}