frambuffer lcd.c

/**
*lcd.c
*/
#include <unistd.h>  
#include <stdio.h>  
#include <stdlib.h>  
#include <fcntl.h>  
#include <string.h>  
#include <linux/fb.h>  
#include <sys/mman.h>  
#include <sys/ioctl.h>  
#include <arpa/inet.h>  
#include "type.h"
#include "lcd.h"
 

lcd_t lcd;

s32 lcd_fb_init(void)
{
    //打开显示设备  
    lcd.fd = open("/dev/fb0", O_RDWR);  
    if (!lcd.fd)  
    {  
        printf("Error: open /dev/fb0
");  
        return -1;
    }  

    //get fix information
    if (ioctl(lcd.fd, FBIOGET_FSCREENINFO, &lcd.finfo))  
    {  
        printf("Error: get fix info");  
        return -1;
    }  

    //get variable information
    if (ioctl(lcd.fd, FBIOGET_VSCREENINFO, &lcd.vinfo))  
    {  
        printf("Error: get var info");  
        return -1;
    }  

    lcd.vinfo.bits_per_pixel = 16;
    //lcd screen byte size
    lcd.screensize = lcd.vinfo.xres * lcd.vinfo.bits_per_pixel / 8 + 
            lcd.vinfo.yres *lcd.vinfo.xres;

    //对象映射  
    lcd.fbp = (u8 *)mmap(0, lcd.screensize, PROT_READ | PROT_WRITE, MAP_SHARED, lcd.fd, 0);  
    if ((int)lcd.fbp == -1)  
    {  
        printf("Error: mmap
");  
        return -1;
    }  
}
void lcd_fb_release(void)
{
    /*释放缓冲区，关闭设备*/
    munmap(lcd.fbp, lcd.screensize);  
    close(lcd.fd);  
    return ;  
}

void lcd_fb_clear(void)
{
    memset(lcd.fbp, 0, lcd.screensize);
    return ;  
}

void lcd_fb_info(void)
{
    printf("xres: %d
", lcd.vinfo.xres);
    printf("yres: %d
", lcd.vinfo.yres);
    printf("screensize: %d
", lcd.screensize);
    printf("bits_per_pixel: %d
", lcd.vinfo.bits_per_pixel);
    return;
}


void lcd_fb_put_pixel(u16 x, u16 y, color_t color)
{ 
    u32 location;
    if (x > lcd.vinfo.xres - 1) x = lcd.vinfo.xres - 1;
    if (y > lcd.vinfo.yres - 1) y = lcd.vinfo.yres - 1;
    location = x * lcd.vinfo.bits_per_pixel / 8 + y * lcd.vinfo.xres;
    if (y%2) location -= (lcd.vinfo.yres + 80);/*if you know why? please tell me*/

    if (32 == lcd.vinfo.bits_per_pixel)
    {
        *((u8*) (lcd.fbp + location)) = color.r;
        *((u8*) (lcd.fbp + location + 1)) = color.g;
        *((u8*) (lcd.fbp + location + 2)) = color.b;
        *((u8*) (lcd.fbp + location + 3)) = 0;/*transplite, unused*/
    }
    else if (16 == lcd.vinfo.bits_per_pixel)
    {
        *((u16*)(lcd.fbp + location)) = (u16)(color.r << 11 | color.g << 5 |color.b );        
    }
    else 
    {
        ;//
    }
}

void lcd_fb_draw_line(u16 x1, u16 y1, u16 x2, u16 y2, color_t color)
{
    int i = 0;
    int d = 0;
    if (abs(y2 - y1) > abs(x2 - x1))
    {
        d = (y2 > y1) ? 1 : -1;
        for (i = y1; i != y2; i +=d)
        {
            lcd_fb_put_pixel(x1 + (i - y1) * (x2 - x1) / (y2 - y1), i, color);
        }
    }
    else 
    {
        d = (x2 > x1) ? 1 : -1;
        for (i = x1; i != x2; i+=d)
        {
            lcd_fb_put_pixel(i, y1 + (i - x1) * (y2 - y1) / (x2 - x1), color);
        }
    }
}