simple osc framebuffer beginnings

osc_fb.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/fb.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <inttypes.h>
#include <math.h>
#include "lo/lo.h"

//liblo below
int done = 0;
void error(int num, const char *m, const char *path);
int quit_handler(const char *path, const char *types, lo_arg ** argv,
                 int argc, void *data, void *user_data);
int line_handler(const char *path, const char *types, lo_arg ** argv,
                int argc, void *data, void *user_data);
int circle_handler(const char *path, const char *types, lo_arg ** argv,
                int argc, void *data, void *user_data);
int box_handler(const char *path, const char *types, lo_arg ** argv,
                int argc, void *data, void *user_data);
//framebuffer below
//we're on a 320x240 16bpp rgb565 ili9341 display
int fbfd = 0;
struct fb_var_screeninfo vinfo;
struct fb_fix_screeninfo finfo;
long int screensize = 0;
char *fbp = 0;
int x = 0, y = 0;
long int location = 0;
int maxx, maxy;
void setPixel(int x, int y, uint16_t pixel)
{
    //uint16_t  pixel = (r << 11) | (g << 5) | b;
    uint32_t location = (x+vinfo.xoffset) * (vinfo.bits_per_pixel/8) +
                        (y/2+vinfo.yoffset) * finfo.line_length;
    *((uint16_t*)(fbp + location)) = pixel;
}

int main()
{
    fbfd = open("/dev/fb0", O_RDWR);
    ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo);
    ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo);
    printf("%dx%d, %dbpp\n", vinfo.xres, vinfo.yres, vinfo.bits_per_pixel);
    screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
    fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fbfd, 0);
    maxx = vinfo.xres-1;
    maxy = vinfo.yres-1;

    lo_server_thread st = lo_server_thread_new("7770", error);
    lo_server_thread_add_method(st, "/quit", "", quit_handler, NULL);
    lo_server_thread_add_method(st, "/line", "iiiiiii", line_handler, NULL);
    lo_server_thread_add_method(st, "/circle", "iiiiii", circle_handler, NULL);
    lo_server_thread_add_method(st, "/box", "iiiiiii", box_handler, NULL);
    lo_server_thread_start(st);
    while (!done) { usleep(1000); }
    lo_server_thread_free(st);
    munmap(fbp, screensize);
    return 0;
}

void error(int num, const char *msg, const char *path)
{
    printf("liblo server error %d in path %s: %s\n", num, path, msg);
    fflush(stdout);
}
void circle(int x, int y, int radius, uint16_t color)
{
    uint16_t theta = 1;
    while (theta < 360)
    {
        int curx = (int) x + radius*(cos(theta));
        int cury = (int) y + radius*(sin(theta));
        setPixel( curx, cury, color);
        theta += 1;
    }
}

void line(int x0, int y0, int x1, int y1, uint16_t color )
{ 
  int dx = abs(x1-x0), sx = x0<x1 ? 1 : -1;
  int dy = abs(y1-y0), sy = y0<y1 ? 1 : -1; 
  int err = (dx>dy ? dx : -dy)/2, e2;
  for(;;){
    setPixel(x0,y0,color);
    if (x0==x1 && y0==y1) break;
    e2 = err;
    if (e2 >-dx) { err -= dy; x0 += sx; }
    if (e2 < dy) { err += dx; y0 += sy; }
  }
}
int min(int num1, int num2) { return (num1 > num2 ) ? num2 : num1; }
int line_handler(const char *path, const char *types, lo_arg ** argv,
                int argc, void *data, void *user_data)
{
    int xstart = min(argv[0]->i, maxx);
    int ystart = min(argv[1]->i, maxy);
    int xend   = min(argv[2]->i, maxx);
    int yend   = min(argv[3]->i, maxy);
    uint8_t red   =  (uint8_t) min(argv[4]->i, 0xFF); //0 through 31
    uint8_t green =  (uint8_t) min(argv[5]->i, 0xFF); //0 through 63
    uint8_t blue  =  (uint8_t) min(argv[6]->i, 0xFF); //0 through 31
    uint16_t color = ((red << 11) & 0xF800 ) | ((green << 6) & 0x07E0) | (blue & 0x1F);
    line(xstart, ystart, xend, yend, color);
    return 0;
}

int circle_handler(const char *path, const char *types, lo_arg ** argv,
                int argc, void *data, void *user_data)
{
    int x = min(argv[0]->i, maxx);
    int y = min(argv[1]->i, maxy);
    int radius   = argv[2]->i;

    uint8_t red   =  (uint8_t) min(argv[3]->i, 0xFF); //0 through 31
    uint8_t green =  (uint8_t) min(argv[4]->i, 0xFF); //0 through 63
    uint8_t blue  =  (uint8_t) min(argv[5]->i, 0xFF); //0 through 31
    uint16_t color = ((red << 11) & 0xF800 ) | ((green << 6) & 0x07E0) | (blue & 0x1F);
    circle(x, y, radius, color);
    return 0;
}
int box_handler(const char *path, const char *types, lo_arg ** argv,
                int argc, void *data, void *user_data)
{
    int x = min(argv[0]->i, maxx);
    int y = min(argv[1]->i, maxy);
    int width = min(argv[2]->i, maxx);
    int height = min(argv[3]->i, maxy);
    uint8_t red   =  (uint8_t) min(argv[4]->i, 0xFF); //0 through 31
    uint8_t green =  (uint8_t) min(argv[5]->i, 0xFF); //0 through 63
    uint8_t blue  =  (uint8_t) min(argv[6]->i, 0xFF); //0 through 31
    uint16_t color = ((red << 11) & 0xF800 ) | ((green << 6) & 0x07E0) | (blue & 0x1F);
    line(x,y, min(x+width,  maxx), y, color);
    line(x,y,x, min(y+height, maxy), color);
    line(min(x+width, maxx), y, min(x+width, maxx), min(y+height, maxy), color);
    line(x,min(y+height, maxy), min(x+width, maxx), min(y+height, maxy), color);

}

int quit_handler(const char *path, const char *types, lo_arg ** argv,
                 int argc, void *data, void *user_data)
{
    done = 1;
    printf("quiting\n\n");
    fflush(stdout);
    return 0;
}
// gcc osc_fb.c -o f -llo -lm
/*
oscsend 127.0.0.1 7770 /line iiiiiii 0 0 319 240 31 15 0

oscsend 127.0.0.1 7770 /circle iiiiii 160 120 80 31 15 31

oscsend 127.0.0.1 7770 /box iiiiiii 80 80 40  20 31 15 31

*/