91 lines
2.2 KiB
C
91 lines
2.2 KiB
C
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#include "screenbuffer.h"
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#include <unistd.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <string.h>
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#include <fcntl.h>
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#include <linux/fb.h>
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#include <sys/mman.h>
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#include <sys/ioctl.h>
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int fbfd = 0;
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struct fb_var_screeninfo orig_vinfo;
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struct fb_var_screeninfo vinfo;
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struct fb_fix_screeninfo finfo;
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long int screensize = 0;
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char *fbp = 0;
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int8_t init_frame_buffer(void)
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{
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// Open the file for reading and writing
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fbfd = open("/dev/fb0", O_RDWR);
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if (!fbfd) {
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printf("Error: cannot open framebuffer device.\n");
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return 0;
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}
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printf("The framebuffer device was opened successfully.\n");
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// Get variable screen information
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if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo)) {
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printf("Error reading variable information.\n");
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return 0;
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}
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printf("Original %dx%d, %dbpp\n", vinfo.xres, vinfo.yres,
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vinfo.bits_per_pixel );
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// Store for reset (copy vinfo to vinfo_orig)
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memcpy(&orig_vinfo, &vinfo, sizeof(struct fb_var_screeninfo));
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// Change variable info
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vinfo.bits_per_pixel = 24;
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if (ioctl(fbfd, FBIOPUT_VSCREENINFO, &vinfo)) {
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printf("Error setting variable information.\n");
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return 0;
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}
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// Get fixed screen information
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if (ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo)) {
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printf("Error reading fixed information.\n");
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return 0;
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}
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// map fb to user mem
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screensize = finfo.smem_len;
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fbp = (char*)mmap(0,
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screensize,
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PROT_READ | PROT_WRITE,
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MAP_SHARED,
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fbfd,
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0);
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if ((long)fbp == -1) {
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printf("Error: Failed to mmap.\n");
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return 0;
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}
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return 1;
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}
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void deinit_frame_buffer(void)
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{
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// cleanup
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munmap((void *)fbp, screensize);
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if (ioctl(fbfd, FBIOPUT_VSCREENINFO, &orig_vinfo)) {
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printf("Error re-setting variable information.\n");
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}
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close(fbfd);
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}
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void write_pixel_to_screen(uint16_t x, uint16_t y, uint16_t r, uint16_t g, uint16_t b, uint8_t a){
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unsigned int pix_offset;
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unsigned bpp = vinfo.bits_per_pixel / 8;
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if(x < vinfo.xres && y < vinfo.yres){
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pix_offset = bpp * x + y * finfo.line_length;
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fbp[pix_offset++] = r;
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fbp[pix_offset++] = g;
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fbp[pix_offset] = b;
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}
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}
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