Usermode - Removed axwin2 (completly defunct)

[tpg/acess2.git] / Notes / SIF.txt

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+=== Simple Image Format ===
+
+U16    Magic   0x51F0  - This determines the endianness of the file
+U16    Flags
+       > 0-2: Compression (0: Uncompressed, 1: RLE, 2: zlib, 3: RLE-Channel)
+       > 3-5: Format (0: ARGB, 1: RGB
+U16    Width
+U16    Height
+<DATA>
+
+
+=== Compression Formats ===
+0 - Uncompressed
+       The file data is a linear sequence of Width * Height 32-bit ARGB
+       words (in file endianness, determined by the magic)
+
+1 - RLE-4
+       7-bit length followed by a 32-bit value that is repeated `n` times
+       (if bit 7 of the length byte is set, the next `n` 32-bit words are
+       verbatim)
+
+2 - zlib
+       The image data is a zlib stream of 32-bit xRGB words
+
+3 - RLE-Channel
+       The data is the alpha values, followed by red, then green, then blue
+       encoded as RLE with a 7-bit length and a verbatim flag (same as mode
+       1, except with 8-bit values instead of 32-bit)