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rust-raspberrypi-OS-tutorials/.0A_pcscreenfont
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Andre Richter e6ab38f228 Hide tuts not implemented in Rust yet
2018-03-31 20:06:27 +02:00
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delays.c Hide tuts not implemented in Rust yet 2018-03-31 20:06:27 +02:00
delays.h Hide tuts not implemented in Rust yet 2018-03-31 20:06:27 +02:00
font.psf Hide tuts not implemented in Rust yet 2018-03-31 20:06:27 +02:00
gpio.h Hide tuts not implemented in Rust yet 2018-03-31 20:06:27 +02:00
kernel8.img Hide tuts not implemented in Rust yet 2018-03-31 20:06:27 +02:00
lfb.c Hide tuts not implemented in Rust yet 2018-03-31 20:06:27 +02:00
lfb.h Hide tuts not implemented in Rust yet 2018-03-31 20:06:27 +02:00
link.ld Hide tuts not implemented in Rust yet 2018-03-31 20:06:27 +02:00
main.c Hide tuts not implemented in Rust yet 2018-03-31 20:06:27 +02:00
Makefile Hide tuts not implemented in Rust yet 2018-03-31 20:06:27 +02:00
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OLVASSEL.md Hide tuts not implemented in Rust yet 2018-03-31 20:06:27 +02:00
README.md Hide tuts not implemented in Rust yet 2018-03-31 20:06:27 +02:00
start.S Hide tuts not implemented in Rust yet 2018-03-31 20:06:27 +02:00
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uart.h Hide tuts not implemented in Rust yet 2018-03-31 20:06:27 +02:00

README.md

Tutorial 0A - PC Screen Font

Drawing pixmaps is fun, but definitely there's a need to display characters as well. Basicaly fonts are nothing more than bitmaps for each character. For this tutorial I choosed PC Screen Font format, the same Linux Console uses.

Lfb.h, lfb.c

lfb_init() sets up resolution, depth, and color channel order. Also queries framebuffer's address.

lfb_print(x,y,s) displays a string on screen.

Font.psf

The font file. Use any file from /usr/share/kbd/consolefonts. Unicode table is not supported. Translating characters to glyph index using that table (instead of one-to-one relation) is a homework for you. This font is generated from the original IBM PC VGA 8x16 Font ROM, and includes 127 glyphs.

Makefile

I've added a new object file, generated from the psf. It's a good example of how to include and reference a binary file in C. I've used the following command to find out the label:

$ aarch64-elf-readelf -s font.o
        ... output removed for clearity ...
     2: 0000000000000820     0 NOTYPE  GLOBAL DEFAULT    1 _binary_font_psf_end
     3: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT    1 _binary_font_psf_start
     4: 0000000000000820     0 NOTYPE  GLOBAL DEFAULT  ABS _binary_font_psf_size

Main

Very simple. We set the resolution and display the string.