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=={{header|ARM Assembly}}==
This is ana exampleslightly ofdifferent take on the age-old XOR technique to flip the colors of a monochrome graphic. While the Game Boy Advance uses 16 bits per pixel, we'll canuse simplya applymonochrome thebitmap XORfont, priorwhere each bit that's a 1 is an instruction to unpackingfill in a pixel and each bit that's a 0 is an instruction to leave it blank. By flipping the textbits of the font itself, we can create the "inverse video" graphicseffect. The bitmapARM's font<code>EOR</code> andinstruction printcan't routinesbe createdused byto Keithwrite ofto [http:/memory directly; you would have to load from memory into a register first, apply the <code>EOR</wwwcode> operation with the desired value, and write back.chibiakumas.com ChibiAkumas]Our method of flipping the bits of the font will save time.
The Game Boy Advance's video memory is very simple, a two-dimensional array of 16-bit values ranging from memory locations <code>0x06000000</code> to <code>0x06012BFF</code> represents each pixel of the screen. Write a 15-bit hex color value to an element of the array to turn the corresponding pixel to that color value.
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