/*`
    fbv  --  simple image viewer for the linux framebuffer
    Copyright (C) 2000  Tomasz Sterna
    Copyright (C) 2003  Mateusz Golicz

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <asm/types.h>
#include <string.h>
#include <errno.h>
#include <linux/fb.h>

#include "fbv.h"

/* Public Use Functions:
 *
 * extern void fb_display(unsigned char *rgbbuff,
 *     int x_size, int y_size,
 *     int x_pan, int y_pan,
 *     int x_offs, int y_offs);
 *
 * extern void getCurrentRes(int *x,int *y);
 *
 */

unsigned short red[256], green[256], blue[256];
struct fb_cmap map332 = {0, 256, red, green, blue, NULL};
unsigned short red_b[256], green_b[256], blue_b[256];
struct fb_cmap map_back = {0, 256, red_b, green_b, blue_b, NULL};


int openFB(const char *name);
void closeFB(int fh);
void getVarScreenInfo(int fh, struct fb_var_screeninfo *var);
void setVarScreenInfo(int fh, struct fb_var_screeninfo *var);
void getFixScreenInfo(int fh, struct fb_fix_screeninfo *fix);
void set332map(int fh);
void* convertRGB2FB(int fh, unsigned char *rgbbuff, unsigned long count, int bpp, int *cpp);
void blit2FB(int fh, void *fbbuff, unsigned char *alpha,
	unsigned int pic_xs, unsigned int pic_ys,
	unsigned int scr_xs, unsigned int scr_ys,
	unsigned int xp, unsigned int yp,
	unsigned int xoffs, unsigned int yoffs,
	int cpp);

void fb_display(unsigned char *rgbbuff, unsigned char * alpha, int x_size, int y_size, int x_pan, int y_pan, int x_offs, int y_offs)
{
	printf("function : %s\n", __func__);
	printf("\tparalist : x_size=%d, y_size=%d, x_pan=%d, y_pan=%d, x_offs=%d, y_offs=%d\n", x_size, y_size, x_pan, y_pan, x_offs, y_offs);

    struct fb_var_screeninfo var;
    struct fb_fix_screeninfo fix;
    unsigned short *fbbuff = NULL;
    int fh = -1, bp = 0;
    unsigned long x_stride;
    
    /* get the framebuffer device handle */
    fh = openFB(NULL);
    
    /* read current video mode */
    getVarScreenInfo(fh, &var);	// framebuffer可变信息
    getFixScreenInfo(fh, &fix);	// framebuffer固定信息
    
    // framebuffer每行能表示的像素点数
    x_stride = (fix.line_length * 8) / var.bits_per_pixel;
   
    /* correct panning */
    // 平移量如果会使图像跑出framebuffer能够显示的区域，则不平移
    if(x_pan > x_size - x_stride) x_pan = 0;
    if(y_pan > y_size - var.yres) y_pan = 0;
    /* correct offset */
    if(x_offs + x_size > x_stride) x_offs = 0;
    if(y_offs + y_size > var.yres) y_offs = 0;
    
    /* blit buffer 2 fb */
    fbbuff = convertRGB2FB(fh, rgbbuff, x_size * y_size, var.bits_per_pixel, &bp);
#if 0
    blit2FB(fh, fbbuff, alpha, x_size, y_size, x_stride, var.yres, x_pan, y_pan, x_offs, y_offs, bp);
#else
    blit2FB(fh, fbbuff, alpha, x_size, y_size, x_stride, var.yres_virtual, x_pan, y_pan, x_offs, y_offs + var.yoffset, bp);
#endif
    free(fbbuff);
   
    /* close device */
    closeFB(fh);
}

void getCurrentRes(int *x, int *y)
{
    struct fb_var_screeninfo var;
    int fh = -1;
    fh = openFB(NULL);
    getVarScreenInfo(fh, &var);
    *x = var.xres;
    *y = var.yres;
    closeFB(fh);
}

int openFB(const char *name)
{
    int fh;
    char *dev;

    if(name == NULL){
	dev = getenv("FRAMEBUFFER");
	if(dev) name = dev;
	else name = DEFAULT_FRAMEBUFFER;
    }
    
    if ((fh = open(name, O_RDWR)) == -1){
        fprintf(stderr, "open %s: %s\n", name, strerror(errno));
        exit(1);
    }
    return fh;
}

void closeFB(int fh)
{
    close(fh);
}

int clearFB(const char *name)
{
	printf("function : %s\n", __func__);
	printf("\tparalist : name=%s\n", name);

	int fh = -1;
	unsigned char *fb = NULL;
	struct fb_fix_screeninfo fix;

	if(-1 != (fh = openFB(name))){
		getFixScreenInfo(fh, &fix);
		printf("fix.smem_len=%u\n", fix.smem_len);
		if(MAP_FAILED == (fb = mmap(NULL, fix.smem_len, PROT_WRITE, MAP_SHARED, fh, 0))){
			perror("mmap");
			closeFB(fh);
			return -1;
		}
	}

	// clear FB
	memset(fb, 0, fix.smem_len);

	munmap(fb, fix.smem_len);
	closeFB(fh);

	return 0;
}

void getVarScreenInfo(int fh, struct fb_var_screeninfo *var)
{
    if (ioctl(fh, FBIOGET_VSCREENINFO, var)){
        fprintf(stderr, "ioctl FBIOGET_VSCREENINFO: %s\n", strerror(errno));
        exit(1);
    }
}

void setVarScreenInfo(int fh, struct fb_var_screeninfo *var)
{
    if (ioctl(fh, FBIOPUT_VSCREENINFO, var)){
        fprintf(stderr, "ioctl FBIOPUT_VSCREENINFO: %s\n", strerror(errno));
	exit(1);
    }
}

void getFixScreenInfo(int fh, struct fb_fix_screeninfo *fix)
{
    if (ioctl(fh, FBIOGET_FSCREENINFO, fix)){
        fprintf(stderr, "ioctl FBIOGET_FSCREENINFO: %s\n", strerror(errno));
	exit(1);
    }
}

void make332map(struct fb_cmap *map)
{
	int rs, gs, bs, i;
	int r = 8, g = 8, b = 4;

	map->red = red;
	map->green = green;
	map->blue = blue;

	rs = 256 / (r - 1);
	gs = 256 / (g - 1);
	bs = 256 / (b - 1);
	
	for (i = 0; i < 256; i++) {
		map->red[i]   = (rs * ((i / (g * b)) % r)) * 255;
		map->green[i] = (gs * ((i / b) % g)) * 255;
		map->blue[i]  = (bs * ((i) % b)) * 255;
	}
}

void set8map(int fh, struct fb_cmap *map)
{
    if (ioctl(fh, FBIOPUTCMAP, map) < 0) {
        fprintf(stderr, "Error putting colormap");
        exit(1);
    }
}

void get8map(int fh, struct fb_cmap *map)
{
    if (ioctl(fh, FBIOGETCMAP, map) < 0) {
        fprintf(stderr, "Error getting colormap");
        exit(1);
    }
}

void set332map(int fh)
{
    make332map(&map332);
    set8map(fh, &map332);
}

void blit2FB(int fh, void *fbbuff, unsigned char *alpha,
	unsigned int pic_xs, unsigned int pic_ys,
	unsigned int scr_xs, unsigned int scr_ys,
	unsigned int xp, unsigned int yp,
	unsigned int xoffs, unsigned int yoffs,
	int cpp)
{
    int i, xc, yc;
	unsigned char *fb;
	
	unsigned char *fbptr;
	unsigned char *imptr;
	
    xc = (pic_xs > scr_xs) ? scr_xs : pic_xs;
    yc = (pic_ys > scr_ys) ? scr_ys : pic_ys;
    
	fb = mmap(NULL, scr_xs * scr_ys * cpp, PROT_WRITE | PROT_READ, MAP_SHARED, fh, 0);
	
	if(fb == MAP_FAILED)
	{
		perror("mmap");
		return;
	}

	if(cpp == 1)
	{
		// 对于色深为8位或8位以下的设备,在进行绘图操作前还需要设置合适的调色板
	    get8map(fh, &map_back);
	    set332map(fh);
	}

	fbptr = fb     + (yoffs * scr_xs + xoffs) * cpp;
	imptr = fbbuff + (yp	* pic_xs + xp) * cpp;
	
	if(alpha)
	{
	 	unsigned char * alphaptr;
		int from, to, x;
		
		alphaptr = alpha + (yp	* pic_xs + xp);
		
		for(i = 0; i < yc; i++, fbptr += scr_xs * cpp, imptr += pic_xs * cpp, alphaptr += pic_xs)
		{
			for(x = 0; x<xc; x++)
			{
				int v;
				
				from = to = -1;
				for(v = x; v<xc; v++)
				{
					if(from == -1)
					{
						if(alphaptr[v] > 0x80) from = v;
					}
					else
					{
						if(alphaptr[v] < 0x80)
						{
							to = v;
							break;
						}
					}
				}
				if(from == -1)
					break;
					
				if(to == -1) to = xc;
				
				memcpy(fbptr + (from * cpp), imptr + (from * cpp), (to - from - 1) * cpp);
				x += to - from - 1;
			}
		}
	}
	else
	    for(i = 0; i < yc; i++, fbptr += scr_xs * cpp, imptr += pic_xs * cpp)
			memcpy(fbptr, imptr, xc * cpp);
		
	if(cpp == 1)
	    set8map(fh, &map_back);
	
	munmap(fb, scr_xs * scr_ys * cpp);
}

inline static unsigned char make8color(unsigned char r, unsigned char g, unsigned char b)
{
    return (
	(((r >> 5) & 7) << 5) |
	(((g >> 5) & 7) << 2) |
	 ((b >> 6) & 3)       );
}

inline static unsigned short make15color(unsigned char r, unsigned char g, unsigned char b)
{
    return (
	(((r >> 3) & 31) << 10) |
	(((g >> 3) & 31) << 5)  |
	 ((b >> 3) & 31)        );
}

inline static unsigned short make16color(unsigned char r, unsigned char g, unsigned char b)
{
    return (
	(((r >> 3) & 31) << 11) |
	(((g >> 2) & 63) << 5)  |
	 ((b >> 3) & 31)        );
}

void* convertRGB2FB(int fh, unsigned char *rgbbuff, unsigned long count, int bpp, int *cpp)
{
    unsigned long i;
    void *fbbuff = NULL;
	u_int8_t  *c_fbbuff;
    u_int16_t *s_fbbuff;
    u_int32_t *i_fbbuff;

    // 像素位深度
    switch(bpp)
    {
	case 8:
	    *cpp = 1;
	    c_fbbuff = (unsigned char *) malloc(count * sizeof(unsigned char));
	    for(i = 0; i < count; i++)
	    	c_fbbuff[i] = make8color(rgbbuff[i*3], rgbbuff[i*3+1], rgbbuff[i*3+2]);
	    fbbuff = (void *) c_fbbuff;
	    break;
	case 15:
	    *cpp = 2;
	    s_fbbuff = (unsigned short *) malloc(count * sizeof(unsigned short));
	    for(i = 0; i < count ; i++)
	    	s_fbbuff[i] = make15color(rgbbuff[i*3], rgbbuff[i*3+1], rgbbuff[i*3+2]);
	    fbbuff = (void *) s_fbbuff;
	    break;
	case 16:
	    *cpp = 2;
	    s_fbbuff = (unsigned short *) malloc(count * sizeof(unsigned short));
	    for(i = 0; i < count ; i++)
	    	s_fbbuff[i] = make16color(rgbbuff[i*3], rgbbuff[i*3+1], rgbbuff[i*3+2]);
	    fbbuff = (void *) s_fbbuff;
	    break;
	case 24:
	case 32:
	    *cpp = 4;
	    i_fbbuff = (unsigned int *) malloc(count * sizeof(unsigned int));
	    for(i = 0; i < count ; i++)
	    	i_fbbuff[i] =	((rgbbuff[i*3] << 16) & 0xFF0000)	|
	    					((rgbbuff[i*3+1] << 8) & 0xFF00)	|
	    					(rgbbuff[i*3+2] & 0xFF);
	    fbbuff = (void *) i_fbbuff;
	    break;
	default:
	    fprintf(stderr, "Unsupported video mode! You've got: %dbpp\n", bpp);
	    exit(1);
    }
    return fbbuff;
}