Mirai's Miscellaneous Misadventures

M47 / engines / fbdev.c

/* license: AGPLv3 or later */
/* copyright 2023 zamfofex */

#include <unistd.h>
#include <stdlib.h>
#include <termios.h>
#include <time.h>
#include <fcntl.h>
#include <stdint.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <linux/fb.h>
#include <linux/kd.h>
#include <linux/input.h>

#include <mimimi.h>

struct mimimi_fbdev
{
	unsigned char *buffer;
	int width, height;
	int x_offset, y_offset;
	int line_length;
	int bytes_per_pixel;
};

static struct termios mimimi_fbdev_tio;

static void mimimi_fbdev_exit(void)
{
	ioctl(0, KDSETMODE, KD_TEXT);
	tcsetattr(0, TCSANOW, &mimimi_fbdev_tio);
}

static void mimimi_fbdev_stamp(void *data, int x0, int y0, void *texture)
{
	static unsigned char rch[] = {0x11, 0x44, 0x77, 0x99, 0xCC, 0xFF};
	static unsigned char gch[] = {0x11, 0x33, 0x55, 0x77, 0x99, 0xBB, 0xDD, 0xFF};
	static unsigned char bch[] = {0x22, 0x55, 0x88, 0xBB, 0xEE};
	
	struct mimimi_image *image;
	struct mimimi_fbdev *fbdev_data;
	int x, y;
	int offset_x, offset_y, offset;
	unsigned char color;
	unsigned char r, g, b;
	
	image = texture;
	fbdev_data = data;
	
	for (y = 0 ; y < image->height ; y++)
	for (x = 0 ; x < image->width ; x++)
	{
		if (y + y0 < 0) continue;
		if (x + x0 < 0) continue;
		
		if (y + y0 >= fbdev_data->height) continue;
		if (x + x0 >= fbdev_data->width) continue;
		
		offset_x = (x + x0 + fbdev_data->x_offset) * fbdev_data->bytes_per_pixel;
		offset_y = (y + y0 + fbdev_data->y_offset) * fbdev_data->line_length;
		
		offset = offset_x + offset_y;
		
		color = image->colors[x + y * image->width];
		if (color == 0) continue;
		
		if (fbdev_data->bytes_per_pixel == 4)
			fbdev_data->buffer[offset + 3] = 0xFF;
		
		if (color < 0x10)
		{
			fbdev_data->buffer[offset + 2] = color * 0x11;
			fbdev_data->buffer[offset + 1] = color * 0x11;
			fbdev_data->buffer[offset + 0] = color * 0x11;
			continue;
		}
		
		color -= 0x10;
		r = rch[(color / 40) % 6];
		g = gch[(color / 5) % 8];
		b = bch[(color / 1) % 5];
		
		fbdev_data->buffer[offset + 2] = r;
		fbdev_data->buffer[offset + 1] = g;
		fbdev_data->buffer[offset + 0] = b;
	}
}

static void *mimimi_fbdev_texture(void *data, struct mimimi_image *image)
{
	(void) data;
	return image;
}

static void mimimi_fbdev_invalidate(void *data, void *texture)
{
	(void) data;
	(void) texture;
}

int mimimi_fbdev(void (*start)(void *chapter, struct mimimi_engine *engine), void (*tick)(void *chapter, unsigned char left, unsigned char right), unsigned long int chapter_size)
{
	static char *file_names[] =
	{
		"/dev/input/event0", "/dev/input/event1", "/dev/input/event2", "/dev/input/event3",
		"/dev/input/event4", "/dev/input/event5", "/dev/input/event6", "/dev/input/event7",
		"/dev/input/event8", "/dev/input/event9", "/dev/input/event10", "/dev/input/event11",
		"/dev/input/event12", "/dev/input/event13", "/dev/input/event14", "/dev/input/event15",
		"/dev/input/event16", "/dev/input/event17", "/dev/input/event18", "/dev/input/event19",
		"/dev/input/event20", "/dev/input/event21", "/dev/input/event22", "/dev/input/event23",
		"/dev/input/event24", "/dev/input/event25", "/dev/input/event26", "/dev/input/event27",
		"/dev/input/event28", "/dev/input/event29", "/dev/input/event30", "/dev/input/event31",
	};
	
	void *chapter;
	int fd, in_fd;
	struct fb_fix_screeninfo finfo;
	struct fb_var_screeninfo vinfo;
	void *aux;
	unsigned char *buffer;
	int bytes_per_pixel;
	unsigned int width, height;
	struct mimimi_engine engine;
	struct mimimi_fbdev data;
	int in_count;
	int in[32];
	struct timeval past, tv;
	struct timespec ts;
	long int delay;
	unsigned long int usec;
	int i;
	int nfds;
	int available;
	struct input_event event;
	ssize_t size, r;
	unsigned char left, right;
	fd_set fds;
	tcflag_t flag;
	
	chapter = malloc(chapter_size);
	if (chapter == NULL) return 1;
	
	fd = open("/dev/fb0", O_RDWR);
	if (fd < 0) return 1;
	if (ioctl(fd, FBIOGET_FSCREENINFO, &finfo) < 0) return 1;
	if (ioctl(fd, FBIOGET_VSCREENINFO, &vinfo) < 0) return 1;
	
	aux = malloc(finfo.smem_len);
	if (aux == NULL) return 1;
	
	buffer = mmap(NULL, finfo.smem_len, PROT_WRITE, MAP_SHARED, fd, 0);
	if ((intptr_t) buffer == -1) return 1;
	
	bytes_per_pixel = vinfo.bits_per_pixel / 8;
	if (bytes_per_pixel != 4 && bytes_per_pixel != 3) return 1;
	
	width = 512;
	height = 256;
	
	if (vinfo.xres < width) width = vinfo.xres;
	if (vinfo.yres < height) height = vinfo.yres;
	
	tcgetattr(0, &mimimi_fbdev_tio);
	flag = mimimi_fbdev_tio.c_lflag;
	mimimi_fbdev_tio.c_lflag &= ~ICANON & ~ECHO;
	
	/* ioctl(0, KDSETMODE, KD_GRAPHICS); */
	tcsetattr(0, TCSANOW, &mimimi_fbdev_tio);
	mimimi_fbdev_tio.c_lflag = flag;
	
	atexit(&mimimi_fbdev_exit);
	
	data.buffer = aux;
	data.width = width;
	data.height = height;
	data.x_offset = vinfo.xoffset;
	data.y_offset = vinfo.yoffset;
	data.line_length = finfo.line_length;
	data.bytes_per_pixel = bytes_per_pixel;
	
	engine.data = &data;
	engine.stamp = &mimimi_fbdev_stamp;
	engine.texture = &mimimi_fbdev_texture;
	engine.invalidate = &mimimi_fbdev_invalidate;
	engine.size.width = width;
	engine.size.height = height;
	
	for (in_count = 0 ; in_count < 32 ; in_count++)
	{
		in_fd = open(file_names[in_count], O_RDONLY);
		if (in_fd < 0) break;
		in[in_count] = in_fd;
	}
	
	left = 0;
	right = 0;
	
	past.tv_sec = 0;
	past.tv_usec = 0;
	
	(*start)(chapter, &engine);
	
	for (;;)
	{
		clock_gettime(CLOCK_MONOTONIC, &ts);
		tv.tv_sec = ts.tv_sec;
		tv.tv_usec = ts.tv_nsec / 1000;
		
		delay =
			(tv.tv_sec - past.tv_sec) * 1000000 +
			(tv.tv_usec - past.tv_usec);
		
		if (delay < 0) delay = 0;
		
		past.tv_sec = tv.tv_sec;
		past.tv_usec = tv.tv_usec;
		
		usec = 0;
		if (delay < 33333) usec = 33333 - delay;
		
		tv.tv_sec = usec / 1000000;
		tv.tv_usec = usec % 1000000;
		
		nfds = 0;
		FD_ZERO(&fds);
		for (i = 0 ; i < in_count ; i++)
		{
			if (nfds < in[i]) nfds = in[i];
			FD_SET(in[i], &fds);
		}
		
		for (;;)
		{
			available = select(nfds, &fds, NULL, NULL, &tv);
			if (available == -1) return 1;
			if (available == 0) break;
			
			tv.tv_sec = 0;
			tv.tv_usec = 0;
			
			for (i = 0 ; i < in_count ; i++)
			{
				in_fd = in[i];
				if (FD_ISSET(in_fd, &fds) == 0) continue;
				
				size = sizeof event;
				r = read(in_fd, &event, size);
				if (r < size) return 1;
				
				if (event.type != EV_KEY) continue;
				if (event.value == 2) continue;
				
				switch (event.code)
				{
				case KEY_LEFT:
				case KEY_A:
					left = event.value;
					break;
				case KEY_RIGHT:
				case KEY_D:
					right = event.value;
					break;
				case KEY_Q:
					if (event.value == 0) return 0;
					break;
				}
			}
		}
		
		(*tick)(chapter, left, right);
		memcpy(buffer, aux, finfo.smem_len);
	}
}