Crate snes_bitplanes

This is documentation for the snes-bitplanes crate.

The Super NES includes stores its graphics in bitplanes, a packed format in which the bits representing a specific pixel are spread across multiple bytes in the same bit position.

For example, 2-bit-per-pixel data stored as bitplanes might have the byte representation: rust 00101110 // 0, bitplane 1 01100101 // 1, bitplane 2 11101001 // 2, bitplane 1 10010101 // 3, bitplane 2 // ... 00010101 // 14, bitplane 1 00101110 // 15, bitplane 2 The initial decoded values are 00, 10, 11, 00, 01, 11, 01, 10.

The Super NES is little-endian, so the leftmost bits represent the earliest decoded bytes. Also note that the second bitplane is the more significant bit in the output.

In total, 2bpp data will inflate to 4 times its original size (because Bitplanes iterators yield bytes themselves, even though the values are generally smaller).

Usage

let bitplanes_data = vec![0u8; 128]; // Extremely boring data
let decoded: Vec<Tile> = Bitplanes::new(&bitplanes_data).collect();
for px in decoded[0].chunks(8) {
    // the Tile struct wraps a 64-byte array, and has a similar API
}

Currently only 4-bits-per-pixel (16 color) bitplanes are decodable with this crate. More color depths will be added later.

Thanks

This crate would not be possible without the research of others, notably * FDwR (Frank Dwayne) /snesgfx.txt 1998 * Qwertie (David Piepgrass) /snesdoc.html 1998

Structs

Bitplanes	An iterator over 4-bits-per-pixel bitplanes.
Tile	Tile is a tuple struct wrapping an 8x8 byte array: conceptually a tile of SNES graphics.