This is a real-time solver for 2D transient heat conduction with isothermal boundary conditions in less than 1kB of program space. It is intended to be visualized on an LED board with an equivalent number of LEDs in the x and y directory. It was developed by Vector Space as an entry for the 2017, 1kB Hackaday Challenge.
The following output generated by running make in the avr/src directory shows that when compiled with avr-gcc version 4.9.2 the binary size of the program falls less than or equal to 1kB. 1024 bytes exactly!
avr-gcc --version
avr-gcc (GCC) 4.9.2
Copyright (C) 2014 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
avr-gcc -mmcu=atmega328p -std=gnu99 -Os -ffunction-sections -fdata-sections -Wl,--gc-sections -Wl,-Map=conduction.map -flto -mrelax -lm -nostartfiles -g3 -DNO_VECTORS -DF_CPU=16000000 -I startup/common main.c spi.c adc.c rgb_matrix.c colormap.c conduction.c timer.c interpolate.c startup/crt1/gcrt1.S -o conduction
avr-size conduction
text data bss dec hex filename
1024 0 1600 2624 a40 conduction
avr-objcopy -O ihex -R .eeprom conduction conduction.hex