在AVR-G ++中對元素的未定義引用

Question

我想用cpp中的幾個其他類編譯一個簡單的項目。 不幸的是，當使用avr-g++.exe -o stepper.elf src/add_functions.o src/ASF/common/services/hugemem/avr8/avr8_hugemem.o src/ASF/common/services/sleepmgr/xmega/sleepmgr.o src/ASF/common/services/spi/xmega_spi/spi_master.o src/ASF/xmega/drivers/dma/dma.o src/ASF/xmega/drivers/spi/spi.o src/gpio_control.o src/spi_control.o src/usart_control.o src/ASF/common/boards/user_board/init.o src/ASF/common/services/clock/xmega/sysclk.o src/ASF/common/services/ioport/xmega/ioport_compat.o src/ASF/common/services/serial/usart_serial.o src/ASF/xmega/drivers/cpu/ccp.o src/ASF/xmega/drivers/usart/usart.o src/main.o -Wl,-Map="stepper.map" -Wl,--start-group -Wl,-lm -Wl,--end-group -Wl,--gc-sections -mmcu=atxmega16a4調用avr-g++.exe -o stepper.elf src/add_functions.o src/ASF/common/services/hugemem/avr8/avr8_hugemem.o src/ASF/common/services/sleepmgr/xmega/sleepmgr.o src/ASF/common/services/spi/xmega_spi/spi_master.o src/ASF/xmega/drivers/dma/dma.o src/ASF/xmega/drivers/spi/spi.o src/gpio_control.o src/spi_control.o src/usart_control.o src/ASF/common/boards/user_board/init.o src/ASF/common/services/clock/xmega/sysclk.o src/ASF/common/services/ioport/xmega/ioport_compat.o src/ASF/common/services/serial/usart_serial.o src/ASF/xmega/drivers/cpu/ccp.o src/ASF/xmega/drivers/usart/usart.o src/main.o -Wl,-Map="stepper.map" -Wl,--start-group -Wl,-lm -Wl,--end-group -Wl,--gc-sections -mmcu=atxmega16a4適用於以下代碼：

#include <asf.h>
#include <string.h>
#include "usart.h"

class usart_controller
{
//variables
public:
protected:
private:
    static usart_rs232_options_t USART_options;
    USART_t *usart;
//functions
public:
    usart_controller(USART_t *usart, uint32_t baudrate, USART_CHSIZE_t charlength, USART_PMODE_t paritybyte, bool stopbit);
    ~usart_controller();
    void send_data(uint32_t *data32, size_t data32_size);
    uint8_t * rec_data();
protected:
private:
    usart_controller( const usart_controller &c );
    usart_controller& operator=( const usart_controller &c );

}; //usart_controller


#include "usart_control.h"


// default constructor
usart_controller::usart_controller(USART_t *usart, uint32_t baudrate, USART_CHSIZE_t charlength, USART_PMODE_t paritybyte, bool stopbit)
{
    this->USART_options.baudrate = baudrate;
    //this->USART_SERIAL_OPTIONS.charlength = charlength;
    //this->USART_SERIAL_OPTIONS.paritytype = paritybyte;
    //this->USART_SERIAL_OPTIONS.stopbits = stopbit;
    this->usart = usart;
    //usart_init_rs232(usart, &(this->USART_SERIAL_OPTIONS));
} //usart_controller

// default destructor
usart_controller::~usart_controller()
{
} //~usart_controller

void usart_controller::send_data(uint32_t * data32, size_t data32_size)
{
    size_t data_size = 4 * data32_size;
    uint8_t *data = new uint8_t[data32_size * 4];
    for(unsigned int i = 0; i < data32_size; i++)
    {
        for(int j = 0; j < 4; j++)
        {
            data[i*j+j] = (data32[i] << (j*8));
        }
    }
    usart_serial_write_packet(this->usart, data, data_size * sizeof(uint8_t));
    delete[] data;
}

uint8_t * usart_controller::rec_data()
{
    uint8_t * data = new uint8_t[32];
    usart_serial_read_packet(this->usart, data, 32*sizeof(uint8_t));
    return data;
}

我收到usart_controller::USART_options'" for the command this-> USART_options.baudrate = baudrate;”的錯誤“錯誤：對usart_controller::USART_options'" for the command未定義引用”。 當我單獨編譯它時，一切都很好，並且我得到了一個有效的目標文件。 稍后嘗試鏈接時，出現上面顯示的錯誤。 為什么？ 我錯過了什么？ 我已經鏈接了我需要的一切。

Answer 1

在c ++中，僅在類中聲明靜態數據成員是不夠的。 還必須在某處定義它來為其分配內存。 如果添加

usart_rs232_options_t usart_controller::USART_options;

在源文件中的某個位置（例如，在類定義之后），它將被很好地鏈接:)

PS：Atmel嗎？ 玩得開心，小心那個小魔鬼！ :)