关于数据压缩中位运算求助！

2013-03-18 12:00:56 120 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

智能车实战——极速越野组GPS与惯导融合定位导航全解析本文深入解析了智能车极速越野组中GPS与惯导模块的融合定位导航技术。通过对比GPS的全局定位与惯导的高频姿态感知，详细阐述了如何利用MM32SPN27主控，将两者数据融合以实现精准、实时的车辆控制。内容涵盖硬件选型、软件数据处理、PID控制及系统调试等实战环节，为智能车开发者提供了一套完整的解决方案。阅读详情

在阅读过程中中有下面的
***********************************************************************************
bit_rot_left（）函数说明：
void bit_rot_left(unsigned char *bits, int size, int count );
Return Value None.
Description Rotates the buffer bits, containing size bits, to the left count
bits. After the operation, the leftmostcount bits become the count rightmost bits
in the buffer, and all other bits are shifted accordingly.
Complexity O (n β), where n is the number of bits rotated to the left and β is
the number of bits in the buffer.

函数接口实现 C语言
void bit_rot_left(unsigned char *bits, int size, int count) {
int fbit,
lbit,
i,
j;
/*****************************************************************************
* *
* Rotate the buffer to the left the specified number of bits. *
* *
*****************************************************************************/
if (size > 0) {
for (j = 0; j < count; j++) {
for (i = 0; i <= ((size - 1) / 8); i++) {
/********************************************************************
* *
* Get the bit about to be shifted off the current byte. *
* *
********************************************************************/
lbit = bit_get(&bits[i], 0);
if (i == 0) {
/*****************************************************************
* *
* Save the bit shifted off the first byte for later. *
* *
*****************************************************************/
fbit = lbit;
}
else {
/*****************************************************************
* *
* Set the rightmost bit of the previous byte to the leftmost *
* bit about to be shifted off the current byte. *
* *
*****************************************************************/
bit_set(&bits[i - 1], 7, lbit);
}
/********************************************************************
* *
* Shift the current byte to the left. *
* *
********************************************************************/
bits[i] = bits[i] << 1;
}
/***********************************************************************
* *
* Set the rightmost bit of the buffer to the bit shifted off the *
* first byte. *
* *
***********************************************************************/
bit_set(bits, size - 1, fbit);
}
}
return;
}
int bit_get(const unsigned char *bits, int pos) {
unsigned char mask;
int i;
/*****************************************************************************
* *
* Set a mask for the bit to get. *
* *
*****************************************************************************/
mask = 0x80;
for (i = 0; i < (pos % 8); i++)
mask = mask >> 1;
/*****************************************************************************
* *
* Get the bit. *
* *
*****************************************************************************/
return (((mask & bits[(int)(pos / 8)]) == mask) ? 1 : 0);
}

void bit_set(unsigned char *bits, int pos, int state) {
unsigned char mask;
int i;
/*****************************************************************************
* *
* Set a mask for the bit to set. *
* *
*****************************************************************************/
mask = 0x80;
for (i = 0; i < (pos % 8); i++)
mask = mask >> 1;
/*****************************************************************************
* *
* Set the bit. *
* *
*****************************************************************************/
if (state)
bits[pos / 8] = bits[pos / 8] | mask;
else
bits[pos / 8] = bits[pos / 8] & (~mask);
return;
}

问题是这个代码实在是理解不了～求讲解，或者留下QQ，晚上聊～～

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