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/**
* crt-calibrator – Calibration utility for CRT monitors
* Copyright © 2014 Mattias Andrée (maandree@member.fsf.org)
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "framebuffer.h"
#include <unistd.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <stropts.h>
#include <linux/fb.h>
#include <errno.h>
/**
* The psuedodevice pathname pattern used to access a framebuffer
*/
#ifndef FB_DEVICE_PATTERN
# define FB_DEVICE_PATTERN "/dev/fb%lu"
#endif
/**
* The number of elements to allocates to a buffer for a framebuffer device pathname
*/
#define FB_DEVICE_MAX_LEN (sizeof(FB_DEVICE_PATTERN) / sizeof(char) + 3 * sizeof(size_t))
/**
* Figure out how many framebuffers there are on the system
*
* @return The number of framebuffers on the system
*/
size_t fb_count(void)
{
char buf[FB_DEVICE_MAX_LEN];
size_t count = 0;
for (;; count++)
{
sprintf(buf, FB_DEVICE_PATTERN, count);
if (access(buf, F_OK) < 0)
return count;
}
}
/**
* Open a framebuffer
*
* @param index The index of the framebuffer to open
* @param fb Framebuffer information to fill in
* @return Zero on success, -1 on error
*/
int fb_open(size_t index, framebuffer_t* restrict fb)
{
char buf[FB_DEVICE_MAX_LEN];
struct fb_fix_screeninfo fix_info;
struct fb_var_screeninfo var_info;
int old_errno;
fb->fd = -1;
fb->mem = MAP_FAILED;
sprintf(buf, FB_DEVICE_PATTERN, index);
fb->fd = open(buf, O_RDWR);
if (fb->fd == -1)
goto fail;
if (ioctl(fb->fd, FBIOGET_FSCREENINFO, &fix_info) ||
ioctl(fb->fd, FBIOGET_VSCREENINFO, &var_info))
goto fail;
fb->mem = mmap(NULL, fix_info.smem_len, PROT_WRITE, MAP_SHARED, fb->fd, 0);
if (fb->mem == MAP_FAILED)
goto fail;
fb->mem += var_info.xoffset * (var_info.bits_per_pixel / 8);
fb->mem += var_info.yoffset * fix_info.line_length;
fb->width = var_info.xres;
fb->height = var_info.yres;
fb->bytes_per_pixel = var_info.bits_per_pixel / 8;
fb->line_length = fix_info.line_length;
return 0;
fail:
old_errno = errno;
fb_close(fb);
errno = old_errno;
return -1;
}
/**
* Close a framebuffer
*
* @param fb The framebuffer information
*/
void fb_close(framebuffer_t* restrict fb)
{
if (fb->fd != -1)
close(fb->fd), fb->fd = -1;
}
/**
* Construct an sRGB colour in 32-bit XRGB encoding to
* use when specifying colours
*
* @param red The red component from [0, 255] sRGB
* @param green The green component from [0, 255] sRGB
* @param blue The blue component from [0, 255] sRGB
* @return The colour as one 32-bit integer
*/
uint32_t fb_colour(int red, int green, int blue)
{
uint32_t rc = 0;
rc |= red, rc <<= 8;
rc |= green, rc <<= 8;
rc |= blue;
return rc;
}
/**
* Print a filled in rectangle to a framebuffer
*
* @param fb The framebuffer
* @param colour The colour to use when drawing the rectangle
* @param x The starting pixel on the X axis for the rectangle
* @param y The starting pixel on the Y axis for the rectangle
* @param width The width of the rectangle, in pixels
* @param height The height of the rectangle, in pixels
*/
void fb_fill_rectangle(framebuffer_t* restrict fb, uint32_t colour,
uint32_t x, uint32_t y, uint32_t width, uint32_t height)
{
int8_t* mem = fb->mem + y * fb->line_length;
size_t x1 = x * fb->bytes_per_pixel;
size_t x2 = (x + width) * fb->bytes_per_pixel;
size_t y2 = y + height;
size_t x_, y_;
for (y_ = y; y_ != y2; y_++, mem += fb->line_length)
for (x_ = x1; x_ != x2; x_ += fb->bytes_per_pixel)
{
int8_t* pixel = mem + x_;
*(uint32_t*)pixel = colour;
}
}
/**
* Draw a horizontal line segment on a framebuffer
*
* @param fb The framebuffer
* @param colour The colour to use when drawing the rectangle
* @param x The starting pixel on the X axis for the line segment
* @param y The starting pixel on the Y axis for the line segment
* @param length The length of the line segment, in pixels
*/
void fb_draw_horizontal_line(framebuffer_t* restrict fb, uint32_t colour,
uint32_t x, uint32_t y, uint32_t length)
{
int8_t* mem = fb->mem + y * fb->line_length;
size_t x1 = x * fb->bytes_per_pixel;
size_t x2 = (x + length) * fb->bytes_per_pixel;
size_t x_;
for (x_ = x1; x_ != x2; x_ += fb->bytes_per_pixel)
{
int8_t* pixel = mem + x_;
*(uint32_t*)pixel = colour;
}
}
/**
* Draw a vertical line segment on a framebuffer
*
* @param fb The framebuffer
* @param colour The colour to use when drawing the rectangle
* @param x The starting pixel on the X axis for the line segment
* @param y The starting pixel on the Y axis for the line segment
* @param length The length of the line segment, in pixels
*/
void fb_draw_vertical_line(framebuffer_t* restrict fb, uint32_t colour,
uint32_t x, uint32_t y, uint32_t length)
{
int8_t* mem = fb->mem + y * fb->line_length + x * fb->bytes_per_pixel;
size_t y2 = y + length;
size_t y_;
for (y_ = y; y_ != y2; y_++, mem += fb->line_length)
*(uint32_t*)mem = colour;
}
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