Crack Art

• Company: Detlef Röttger & Jan Borchers
• Extensions: .ca1, .ca2, .ca3

Crack Art was an image drawing program for the Atari ST. Here are the m68k assembly compression and decompression routines, provided by the original program.

16-bit words are stored in big-endian order.

File format

typedef crackart_file {
 uint16_t magic;                /* "CA" */
 uint8_t compressed;            /* 0 = no compression, 1 = compressed */
 uint8_t resolution;            /* 0 = low (320x200x16), 1 = medium (640x200x4), 2 = high (640x400x2) */
 uint16_t palette[palsize];     /* palsize = 16 (low res), 4 (med res) or 0 (high res) */
 uint8_t data[]
} crackart_file;

If the file is uncompressed, sizeof(data) == 32000 bytes of raw video memory.

Uncompressed data format

The image data is stored in a planar format.