源码
移植时主要只修改Tube_Num数量、位选函数Tube_Choose()和单个数码管写入函数Singe_Tube_Write()即可。

数码管基础知识见【51单片机快速入门指南】2.1:数码管显示数字、小数 (科学计数法)
stdint.h内容见【51单片机快速入门指南】一、基础知识和工程创建

Tube.c

#include <REGX52.H>
#include "intrins.h"
#include "stdint.h"
#include "Tube.h"

#define Tube_Port P0

#define Tube_Num  8

sbit Tube_A0 = P2^2;
sbit Tube_A1 = P2^3;
sbit Tube_A2 = P2^4;

//位选
void Tube_Choose(uint8_t num)
{
    Tube_A0 = (num & 1);
    Tube_A1 = (num & 2) >> 1;
    Tube_A2 = (num & 4) >> 2;
}

//显示的延时 400us @11.0592MHz
void LED_Tube_Delay()
{
    unsigned char i;

    _nop_();
    i = 181;
    while (--i);
}

//单个数码管写入数据
void Singe_Tube_Write(uint8_t Data)
{
    Tube_Port = Data;
}

code uint8_t Error_Codes[]=
{
    Tube_Code_E,
    Tube_Code_r,
    Tube_Code_r,
    Tube_Code_o,
    Tube_Code_r
};

int32_t Pow10(int32_t Pow)
{
    int32_t output = 1;
    while (Pow--)
        output *= 10;
    return output;
}

code uint8_t Tube_Codes_0ToF[] =
{
    Tube_Code_0,
    Tube_Code_1,
    Tube_Code_2,
    Tube_Code_3,
    Tube_Code_4,
    Tube_Code_5,
    Tube_Code_6,
    Tube_Code_7,
    Tube_Code_8,
    Tube_Code_9,
    Tube_Code_A,
    Tube_Code_b,
    Tube_Code_C,
    Tube_Code_d,
    Tube_Code_E,
    Tube_Code_F
};

//显示整数
void Display_Int(int32_t Num)
{
    int8_t i = 0;
    uint8_t DisplayNum = 0;
    char Tube_Double_Buffer[Tube_Num] = {0};
    uint8_t Sign_Flag = 0;
    if(Num >= Pow10(Tube_Num) - 1 || Num <= -(Pow10(Tube_Num - 1) - 1))                                    
    {
        for(i = Tube_Num - 1; i >= 0; --i)
        {
            Singe_Tube_Write(Tube_Code_NULL);                    //消隐
            Tube_Choose(i);
            if(Tube_Num - 1 - i < sizeof(Error_Codes))
                Singe_Tube_Write(Error_Codes[Tube_Num - 1 - i]);            //显示
            else
                Singe_Tube_Write(Tube_Code_NULL);
            LED_Tube_Delay();
        }
        return;
    }
    else
    {
        if(Num < 0)
        {
            Sign_Flag = 1;
            Num = -Num;
        }
        for(i = 0; i < Tube_Num; ++i)
        {
            DisplayNum = Num % 10;
            if(Num == 0 && i != 0)
            {
                if(Sign_Flag)
                {
                    Tube_Double_Buffer[i] = Tube_Code_Negative_Sign;    //负号
                    Sign_Flag = 0;
                }
                else
                    Tube_Double_Buffer[i] = Tube_Code_NULL;
            }
            else
                Tube_Double_Buffer[i] = Tube_Codes_0ToF[DisplayNum];
            Num /= 10;
        }

        for(i = 0; i < Tube_Num; ++i)
        {
            Singe_Tube_Write(Tube_Code_NULL);                    //消隐
            Tube_Choose(i);
            Singe_Tube_Write(Tube_Double_Buffer[i]);            //显示
            LED_Tube_Delay();
        }
        return;
    }
}

//显示小数
void Display_Double(double Num)
{
    int8_t i = 0;
    int8_t j = 0;
    uint8_t DisplayNum = 0;
    int32_t Int; 
    int8_t Int_Flag;
    double Double;
    char Tube_Double_Buffer[Tube_Num] = {0};
    if(Num >= Pow10(Tube_Num) - 1 || Num <= -(Pow10(Tube_Num - 1) - 1))                                    
    {
        for(i = Tube_Num - 1; i >= 0; --i)
        {
            Singe_Tube_Write(Tube_Code_NULL);                    //消隐
            Tube_Choose(i);
            if(Tube_Num - 1 - i < sizeof(Error_Codes))
                Singe_Tube_Write(Error_Codes[Tube_Num - 1 - i]);            //显示
            else
                Singe_Tube_Write(Tube_Code_NULL);
            LED_Tube_Delay();
        }
        return;
    }
    else
    {
        if(Num < 0)
        {
            Tube_Double_Buffer[Tube_Num - 1] = Tube_Code_Negative_Sign;    //负号
            Num = -Num;
        }
        Int = (int32_t)Num;
        Double = Num - Int;
        for (j = 0; Int >= Pow10(j); ++j);
        for(i = Tube_Num - 1 - (Tube_Double_Buffer[Tube_Num - 1] == Tube_Code_Negative_Sign), Int_Flag = 1; i >= 0; --i)
        {    
            if(Int_Flag)
                if(Int)
                    for(; j; --j, --i)
                    {
                        Tube_Double_Buffer[i] = Tube_Codes_0ToF[Int / Pow10(j - 1)];
                        Int %= Pow10(j - 1);
                        if (j == 1)
                        {
                            --j;
                            Tube_Double_Buffer[i--] |= Tube_Code_Dot;
                            Int_Flag = 0;
                            break;
                        }
                    }
                else
                {
                    Tube_Double_Buffer[i--] = Tube_Codes_0ToF[0] | Tube_Code_Dot;
                    Int_Flag = 0;
                }
            Double *= 10;
            Tube_Double_Buffer[i] = (uint8_t)(Double + (i == 0) * 0.5);        //末位四舍五入
            Double -= (int)Tube_Double_Buffer[i];
            Tube_Double_Buffer[i] = Tube_Codes_0ToF[Tube_Double_Buffer[i]];
        }
        for(i = 0; i < Tube_Num; ++i)
        {
            Singe_Tube_Write(Tube_Code_NULL);                    //消隐
            Tube_Choose(i);
            Singe_Tube_Write(Tube_Double_Buffer[i]);            //显示
            LED_Tube_Delay();
        }
        return;
    }
}

//显示数字
void Display_Num(double Num)
{
    if(Num == (int32_t)Num)
        Display_Int((int32_t)Num);
    else
        Display_Double(Num);
    return;
}

Tube.h

#ifndef TUBE_H_
#define TUBE_H_

#define Tube_Code_NULL 0x00

#define Tube_Code_0 0x3f
#define Tube_Code_1 0x06
#define Tube_Code_2 0x5b
#define Tube_Code_3 0x4f
#define Tube_Code_4 0x66
#define Tube_Code_5 0x6d
#define Tube_Code_6 0x7d
#define Tube_Code_7 0x07
#define Tube_Code_8 0x7f
#define Tube_Code_9 0x6f

#define Tube_Code_A 0x77
#define Tube_Code_b 0x7c
#define Tube_Code_C 0x39
#define Tube_Code_c 0x58
#define Tube_Code_d 0x5e
#define Tube_Code_E 0x79
#define Tube_Code_F 0x71
#define Tube_Code_G 0x3d
#define Tube_Code_H 0x76
#define Tube_Code_I 0x30
#define Tube_Code_i 0x10
#define Tube_Code_J 0x0e
#define Tube_Code_K    0x7a
#define Tube_Code_L 0x38
#define Tube_Code_M 0x55
#define Tube_Code_n    0x54
#define Tube_Code_o 0x5c
#define Tube_Code_P 0x73
#define Tube_Code_q 0x67
#define Tube_Code_r 0x50
#define Tube_Code_S 0x64
#define Tube_Code_t 0x78
#define Tube_Code_U    0x3e
#define Tube_Code_u 0x1c
#define Tube_Code_v 0x62
#define Tube_Code_W 0x6a
#define Tube_Code_X 0x36
#define Tube_Code_y 0x6e
#define Tube_Code_Z 0x49

#define Tube_Code_Dot 0x80
#define Tube_Code_Negative_Sign 0x40

void Display_Int(int32_t Num);
void Display_Double(double Num);
void Display_Num(double Num);

#endif

main.c

#include <REGX52.H>
#include "intrins.h"
#include "stdint.h"
#include "Tube.h"

void main(void)
{    
    while(1)
    {
        Display_Num(-235);
    }        
}

效果
8位数码管


#define Tube_Port P0

#define Tube_Num  8

sbit Tube_A0 = P2^2;
sbit Tube_A1 = P2^3;
sbit Tube_A2 = P2^4;

//位选
void Tube_Choose(uint8_t num)
{
    Tube_A0 = (num & 1);
    Tube_A1 = (num & 2) >> 1;
    Tube_A2 = (num & 4) >> 2;
}

//显示的延时 400us @11.0592MHz
void LED_Tube_Delay()
{
    unsigned char i;

    _nop_();
    i = 181;
    while (--i);
}

//单个数码管写入数据
void Singe_Tube_Write(uint8_t Data)
{
    Tube_Port = Data;
}

正整数

while(1)
{
    Display_Num(23333);
}


负整数

while(1)
{
    Display_Num(-123456);
}


正小数

while(1)
{
    Display_Num(1.23456);
}


负小数

while(1)
{
    Display_Num(-45.678987);
}


6位数码管

#define Tube_Port P0

#define Tube_Num  6

sbit SEG_DLE = P2^6;
sbit SEG_WLE = P2^7;

//位选
void Tube_Choose(uint8_t num)
{
    SEG_DLE = 0;
    SEG_WLE = 1;
    Tube_Port = ~(0x20 >> num);
    SEG_WLE = 0;
}

//显示的延时 400us @11.0592MHz
void LED_Tube_Delay()
{
    unsigned char i;

    _nop_();
    i = 181;
    while (--i);
}

void Singe_Tube_Write(uint8_t Data)
{
    SEG_DLE = 1;
    SEG_WLE = 0;
    Tube_Port = Data;
    SEG_DLE = 0;
}

正整数

while(1)
{
    Display_Num(23333);
}


负整数

while(1)
{
    Display_Num(-12);
}


正小数

while(1)
{
    Display_Num(1.23456);
}


负小数

while(1)
{
    Display_Num(-45.678987);
}


4位数码管

#define Tube_Port P0

#define Tube_Num  4

sbit Tube_Y0 = P1^0;
sbit Tube_Y1 = P1^1;
sbit Tube_Y2 = P1^2;
sbit Tube_Y3 = P1^3;

//位选
void Tube_Choose(uint8_t num)
{
    switch(num)
    {
        case 0:
            Tube_Y0 = 1;
            Tube_Y1 = 0;
            Tube_Y2 = 0;
            Tube_Y3 = 0;
            break;
        case 1:
            Tube_Y0 = 0;
            Tube_Y1 = 1;
            Tube_Y2 = 0;
            Tube_Y3 = 0;
            break;
        case 2:
            Tube_Y0 = 0;
            Tube_Y1 = 0;
            Tube_Y2 = 1;
            Tube_Y3 = 0;
            break;
        case 3:
            Tube_Y0 = 0;
            Tube_Y1 = 0;
            Tube_Y2 = 0;
            Tube_Y3 = 1;
            break;
    }
}

//显示的延时 1ms @12MHz
void LED_Tube_Delay()
{
    unsigned char i, j;

    i = 2;
    j = 239;
    do
    {
        while (--j);
    } while (--i);
}

void Singe_Tube_Write(uint8_t Data)
{
    Tube_Port = Data;
}

正整数

while(1)
{
    Display_Num(233);
}


负整数

while(1)
{
    Display_Num(-12);
}


正小数

while(1)
{
    Display_Num(1.23456);
}


负小数

while(1)
{
    Display_Num(-45.678987);
}