desert.cx

Here is the algorithm and some C source code to determine if two convex polygons intersect.  Also includes a function to determine if two line segments are intersecting. (Free for any use)

• poly_poly_intersect.c

Here is the algorithm and C source code to determine if a circle and a line segment intersect. (Free for any use)

• lseg_circ_intersect.c

Here's a free implementation of the SHA1 hash algorithm. It is free for any use.

• sha1.h
• sha1.c
• sha1_test.c

This little piece of code calculates the 32 bit CRC of a buffer. It is free for any use.

• crc32.c

Here's a free implementation of AVL trees in C. These are free for any use.

• avltree.h
• avltree.c
• avltest.c

Here are some free linked lists for you. Doubly linked! These are free for any use.

• list.h
• list.c