Lib64bit_t stTmp1; mul64bitHalf(lDx, lDx, &stTmp1); sint mul64bitHalf( int32 NumA, int32 NumB, Lib64bit_t *Answer ) { extend32bitTo64bit( Answer, NumA ); if( mul64bitFull( Answer, NumB ) < 0 ) return FAILURE; return SUCCESS; } void extend32bitTo64bit(Lib64bit_t *Destination,int32 Source)//六十四位存了0和数据 { Destination->High = 0; Destination->Low = Source; if( 0 > Source ){ Destination->High = -1; } } sint mul64bitFull( Lib64bit_t *dest, int32 mul ) { sint Result = 0; LARGE_INTEGER liWork; L64BTtoLI(liWork,dest); liWork.QuadPart *= mul; // Overflow check if( liWork.QuadPart < 0 ) { if(( dest->High > 0 && mul > 0 ) || ( dest->High < 0 && mul < 0 )) { liWork.QuadPart = LONGLONG_NUM(0x7fffffffffffffff); Result = -1; } } else { if(( dest->High < 0 && mul > 0 ) || ( dest->High > 0 && mul < 0 )) { liWork.QuadPart = (LONGLONG)LONGLONG_NUM(0x8000000000000000); Result = -1; } } LItoL64BT(dest,liWork); return Result; }解释一下这段代码
时间: 2024-04-23 19:25:33 浏览: 9
这段代码是 C 语言代码,主要实现了一些对 64 位整数的操作。具体来说,它定义了一个名为 `Lib64bit_t` 的结构体类型,并在其中存储了一个 64 位的整数。结构体中包含了两个成员变量,一个是高 32 位,一个是低 32 位。
接下来是 `mul64bitHalf` 函数,它接受两个 32 位整数作为输入,并将它们相乘的结果存储到一个 `Lib64bit_t` 类型的变量 `stTmp1` 中的低 32 位。
`extend32bitTo64bit` 函数将一个 32 位整数扩展为一个 64 位整数并存储到 `Lib64bit_t` 类型的变量中。如果源数字是负数,则高 32 位设置为 -1,否则为 0。
`mul64bitFull` 函数实现两个 64 位整数的乘法,并将结果存储在第一个参数中。如果结果溢出,则将 `dest` 设置为最大或最小值,并返回 -1。如果没有溢出,则返回 0。
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给下面代码加上注释int GeoLib::CalcDetailDistancePointToPoint( uint32 *Distance, const GeoLocation_t *LocationA, const GeoLocation_t *LocationB ) { if(Distance == NULL || LocationA == NULL || LocationB == NULL) return FAILURE; int32 lAverageLat = (LocationA->latitude + LocationB->latitude)/2; uint32 lDx = 0; uint32 lDy =0; convertLongitudeDifferenceToDetailedMeter(&lDx,abs(LocationA->longitude-LocationB->longitude), lAverageLat); convertLatitudeDifferenceToDetailedMeter(&lDy,abs(LocationA->latitude-LocationB->latitude), lAverageLat); Lib64bit_t stTmp1; Lib64bit_t stTmp2; mul64bitHalf(lDx, lDx, &stTmp1); mul64bitHalf(lDy, lDy, &stTmp2); Lib_iAdd64(&stTmp1, &stTmp2); *Distance = Lib_calcSqrtOf64bit(stTmp1.High, stTmp1.Low); return SUCCESS; }
/*
* 函数名:CalcDetailDistancePointToPoint
* 功能:计算两个地理位置之间的距离
* 参数:
* Distance:返回距离,单位为米
* LocationA:地理位置A,包括经度和纬度
* LocationB:地理位置B,包括经度和纬度
* 返回值:
* SUCCESS:计算成功
* FAILURE:参数错误,计算失败
*/
int GeoLib::CalcDetailDistancePointToPoint( uint32 *Distance, const GeoLocation_t *LocationA, const GeoLocation_t *LocationB ) {
if(Distance == NULL || LocationA == NULL || LocationB == NULL)
return FAILURE;
// 计算平均纬度
int32 lAverageLat = (LocationA->latitude + LocationB->latitude)/2;
// 计算经度差
uint32 lDx = 0;
convertLongitudeDifferenceToDetailedMeter(&lDx,abs(LocationA->longitude-LocationB->longitude), lAverageLat);
// 计算纬度差
uint32 lDy =0;
convertLatitudeDifferenceToDetailedMeter(&lDy,abs(LocationA->latitude-LocationB->latitude), lAverageLat);
// 计算距离的平方
Lib64bit_t stTmp1;
Lib64bit_t stTmp2;
mul64bitHalf(lDx, lDx, &stTmp1);
mul64bitHalf(lDy, lDy, &stTmp2);
Lib_iAdd64(&stTmp1, &stTmp2);
// 计算距离的平方根
*Distance = Lib_calcSqrtOf64bit(stTmp1.High, stTmp1.Low);
return SUCCESS;
}
int GeoLib::CalcDetailDistancePointToPoint( uint32 *Distance, const GeoLocation_t *LocationA, const GeoLocation_t *LocationB )//计算两点之间细节数据 { if(Distance == NULL || LocationA == NULL || LocationB == NULL) return FAILURE; int32 lAverageLat = (LocationA->latitude + LocationB->latitude)/2; uint32 lDx = 0; uint32 lDy =0; convertLongitudeDifferenceToDetailedMeter(&lDx,abs(LocationA->longitude-LocationB->longitude), lAverageLat);//计算两个地理位置的经度和纬度差的绝对值 convertLatitudeDifferenceToDetailedMeter(&lDy,abs(LocationA->latitude-LocationB->latitude), lAverageLat); Lib64bit_t stTmp1; Lib64bit_t stTmp2; mul64bitHalf(lDx, lDx, &stTmp1);//算平方,改写成64位 mul64bitHalf(lDy, lDy, &stTmp2); Lib_iAdd64(&stTmp1, &stTmp2);//算和 *Distance = Lib_calcSqrtOf64bit(stTmp1.High, stTmp1.Low);//开平方 return SUCCESS; }
这是一个计算地理坐标点之间距离的函数,使用的是勾股定理。其中,convertLongitudeDifferenceToDetailedMeter和convertLatitudeDifferenceToDetailedMeter函数用于将经纬度差转换成实际距离(单位为米),mul64bitHalf和Lib_iAdd64函数用于对实际距离进行计算。最后,将计算出的距离开平方得到最终结果(单位为米)。需要注意的是,该函数的输入参数为指向GeoLocation_t类型的指针,包含了地理位置的经度和纬度信息,返回值为成功或失败状态。