请高手指点，STM32F205ZG编码器，定义的变量unsigned int 是16位的下面程序void position(void)转成32位的。不懂！！

寂寞的单车

先谢谢各位大侠了。。

#include "Encinput.h"

/* Struct Define ------------------------------------------------------------*/

NVIC_InitTypeDef NVIC_InitStructure;

TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;

/*************************************

typedef unsigned int DWORD;

typedef unsigned short int WORD;

typedef unsigned char BYTE;

typedef signed int SDWORD;

typedef signed short int SWORD;

typedef signed char SBYTE;
**************************************/

BYTE FloorQuantity = 3;

DWORD floorhigh = 19600;    //

WORD Vanequarter = 163;    //

DWORD floorstate;               //

/* Variable Define -----------------------------------------------------------*/

BYTE F_EncodeDir;

DWORD GetCounter;

DWORD GetCounterNew;

DWORD GetCounterOld;

BYTE F_GetCounter;

DWORD Location = LocationBottom;

BYTE F_Location; //      typedef unsigned char BYTE;

void encoder(void)

{

TIM_ICInitTypeDef  TIMICInitStructure;

/* TIM4 clock enable */

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);

/* GPIOA clock enable */

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12 | GPIO_Pin_13;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

GPIO_Init(GPIOD, &GPIO_InitStructure);

GPIO_PinAFConfig(GPIOD, GPIO_PinSource12, GPIO_AF_TIM4);

GPIO_PinAFConfig(GPIOD, GPIO_PinSource13, GPIO_AF_TIM4);

NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init(&NVIC_InitStructure);

TIM_TimeBaseInitStructure.TIM_Prescaler = 0x0; //No precaling

TIM_TimeBaseInitStructure.TIM_Period = 65535;

TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV4;

TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;

TIM_TimeBaseInit(TIM4 , &TIM_TimeBaseInitStructure);

F_EncodeDir = 1;

GPI12E_T3CON_T3UD(F_EncodeDir); //GPT12E_T3UD(p.posdir);/*ser incremental encoder direction*/

TIMICInitStructure.TIM_ICFilter = 6;

TIM_ICInit(TIM4 ,&TIMICInitStructure);

TIM_ClearFlag(TIM4 ,TIM_FLAG_Update);

TIM_SetCounter(TIM4 ,Location); /* time 4 count register */ //设置TIMx计数器寄存器值

TIM_Cmd(TIM4 ,ENABLE);

GetCounter = TIM_GetCounter(TIM4);                       //获得TIMx计数器的值

}

/*******************************************************************************

* Function Name : position

* Description   : output position signal

* Input         : None

* Output         : None

* Return         : None

*******************************************************************************/

void position(void)

{

/* Count encoder ----------------------------------------------------------*/

if(GetCounter != TIM_GetCounter(TIM4))

{

GetCounter = TIM_GetCounter(TIM4);

}

GetCounterNew = GetCounter; //读取当前位置   

GetCounterOld = Location & 0xFFFF;                        //???????

if(GetCounterNew > GetCounterOld)                             //???????

{

if(GetCounterNew - GetCounterOld > 0x8000)       //???????

{

Location -= 0x00010000;                            //???????

}

}

else                                                                         //???????

{

if(GetCounterOld - GetCounterNew > 0x8000)      //???????

{

Location += 0x00010000;                         //???????

}

}

Location &= 0xFFFF0000;                                          //???????

Location |= GetCounterNew;                                    //???????

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