Currently the following Windows API functions are implemented:
CloseHandle
CreateDirectory
CreateFile
DeleteFile
FileTimeToLocalFileTime
FileTimeToSystemTime
FindClose
FindFirstFile
FindNextFile
GetFileSize
GetFileSizeEx
GetFileTime
GetLastError
ReadFile
RemoveDirectory
SetEndOfFile
SetFilePointer
SetFileTime
SetLastError
SetLastErrorEx
WriteFile

Installation:

Copy libwin32/release/SDK/#? all SDK:

Usage:

gcc blah1.o blah2.o ... -o blah-exe -lwin32 -lauto

Changes:

0.2 (19-Apr-2011)
 - Completely rewritten from scratch and simplified (currently only file
   related functions are implemented)
 - SetFilePointer should now work the same as on Windows (i.e. allows seeking
   beyond end of file)
 - Some additional functions like filetime conversion and creating/deleting
   directories are now implemented

0.1 (5-Mar-2008)
 - First released version

 PERMSSN    UID  GID    PACKED    SIZE  RATIO METHOD CRC     STAMP          NAME
---------- ----------- ------- ------- ------ ---------- ------------ -------------
drwxrwxrwt  1003/513         0       0 ****** -lhd- 0000 Apr 18 13:28 libwin32/
drwxrwxrwt  1003/513         0       0 ****** -lhd- 0000 Apr 20 03:20 libwin32/release/
drwxrwxrwt  1003/513         0       0 ****** -lhd- 0000 Apr 19 05:30 libwin32/release/SDK/
drwxrwxrwt  1003/513         0       0 ****** -lhd- 0000 Apr 19 05:30 libwin32/release/SDK/local/
drwxrwxrwt  1003/513         0       0 ****** -lhd- 0000 Apr 19 05:30 libwin32/release/SDK/local/newlib/
drwxrwxrwt  1003/513         0       0 ****** -lhd- 0000 Apr 20 03:29 libwin32/release/SDK/local/newlib/include/
drwxrwxrwx  1003/513         0       0 ****** -lhd- 0000 Apr 20 02:55 libwin32/release/SDK/local/newlib/include/w32api/
-rwxrwxrwx  1003/513      2420    7177  33.7% -lh7- 23c0 Apr 20 02:55 libwin32/release/SDK/local/newlib/include/w32api/windows.h
-rwxrwxrwx  1003/513      3207   14052  22.8% -lh7- b675 Apr 18 16:53 libwin32/release/SDK/local/newlib/include/w32api/winerror.h
-rwxrwxrwx  1003/513       731    1399  52.3% -lh7- cc67 Apr 19 05:43 libwin32/release/SDK/local/newlib/include/windows.h
drwxrwxrwt  1003/513         0       0 ****** -lhd- 0000 Apr 20 03:29 libwin32/release/SDK/local/newlib/lib/
-rw-r--r--  1003/513      6058   25746  23.5% -lh7- dcb2 Apr 20 03:02 libwin32/release/SDK/local/newlib/lib/libwin32.a
-rwxrwxrwx  1003/513       572    1105  51.8% -lh7- 3f38 Apr 20 03:20 libwin32/release/libwin32.readme
drwxrwxrwt  1003/513         0       0 ****** -lhd- 0000 Apr 20 03:29 libwin32/src/
-rwxrwxrwx  1003/513       455     995  45.7% -lh7- 38d9 Apr 20 02:55 libwin32/src/Makefile
-rwxrwxrwx  1003/513       890    1703  52.3% -lh7- 7cec Apr 19 04:59 libwin32/src/closehandle.c
-rwxrwxrwx  1003/513       901    1694  53.2% -lh7- d16b Apr 20 02:49 libwin32/src/createdirectory.c
-rwxrwxrwx  1003/513      1367    3469  39.4% -lh7- ee34 Apr 19 12:03 libwin32/src/createfile.c
-rwxrwxrwx  1003/513       973    1872  52.0% -lh7- 35c3 Apr 20 01:07 libwin32/src/datestamptofiletime.c
-rwxrwxrwx  1003/513       841    1598  52.6% -lh7- b071 Apr 20 02:54 libwin32/src/deletefile.c
-rwxrwxrwx  1003/513       977    2184  44.7% -lh7- a891 Apr 20 03:02 libwin32/src/dostow32error.c
-rwxrwxrwx  1003/513       976    1854  52.6% -lh7- 9f48 Apr 20 01:08 libwin32/src/filetimetodatestamp.c
-rwxrwxrwx  1003/513       946    1870  50.6% -lh7- 51f8 Apr 20 01:07 libwin32/src/filetimetolocalfiletime.c
-rwxrwxrwx  1003/513      1269    2837  44.7% -lh7- 8064 Apr 20 01:52 libwin32/src/filetimetosystemtime.c
-rwxrwxrwx  1003/513      1560    4302  36.3% -lh7- 9579 Apr 19 23:11 libwin32/src/findfirstfile.c
-rwxrwxrwx  1003/513       980    1976  49.6% -lh7- b46d Apr 19 12:03 libwin32/src/getfilesize.c
-rwxrwxrwx  1003/513       946    1812  52.2% -lh7- a26e Apr 19 12:03 libwin32/src/getfilesizeex.c
-rwxrwxrwx  1003/513      1108    2272  48.8% -lh7- 4558 Apr 20 02:40 libwin32/src/getfiletime.c
-rwxrwxrwx  1003/513       833    1694  49.2% -lh7- 9179 Apr 18 15:39 libwin32/src/getlasterror.c
drwxrwxrwt  1003/513         0       0 ****** -lhd- 0000 Apr 19 05:43 libwin32/src/include/
drwxrwxrwt  1003/513         0       0 ****** -lhd- 0000 Apr 20 02:55 libwin32/src/include/w32api/
-rwxrwxrwx  1003/513      2420    7177  33.7% -lh7- 23c0 Apr 20 02:55 libwin32/src/include/w32api/windows.h
-rwxrwxrwx  1003/513      3207   14052  22.8% -lh7- b675 Apr 18 16:53 libwin32/src/include/w32api/winerror.h
-rwxrwxrwx  1003/513       731    1399  52.3% -lh7- cc67 Apr 19 05:43 libwin32/src/include/windows.h
-rwxrwxrwx  1003/513      1086    2335  46.5% -lh7- 84dd Apr 19 12:03 libwin32/src/readfile.c
-rwxrwxrwx  1003/513       852    1603  53.2% -lh7- ff6c Apr 20 02:51 libwin32/src/removedirectory.c
-rwxrwxrwx  1003/513       981    2099  46.7% -lh7- eec8 Apr 19 12:03 libwin32/src/setendoffile.c
-rwxrwxrwx  1003/513      1202    2908  41.3% -lh7- bcc9 Apr 19 04:45 libwin32/src/setfilepointer.c
-rwxrwxrwx  1003/513      1044    2030  51.4% -lh7- 4312 Apr 20 02:43 libwin32/src/setfiletime.c
drwxrwxrwt  1003/513         0       0 ****** -lhd- 0000 Apr 20 03:29 libwin32/src/tests/
-rwxrwxrwx  1003/513      1323    2722  48.6% -lh7- 33d1 Apr 20 02:06 libwin32/src/tests/listfiles.c
-rwxrwxrwx  1003/513      1030    1973  52.2% -lh7- b52e Apr 19 07:00 libwin32/src/tests/mkfile.c
-rwxrwxrwx  1003/513      1068    2263  47.2% -lh7- 9f17 Apr 20 01:20 libwin32/src/w32private.h
-rwxrwxrwx  1003/513      1120    2439  45.9% -lh7- ad7d Apr 19 12:03 libwin32/src/writefile.c
---------- ----------- ------- ------- ------ ---------- ------------ -------------
 Total        44 files   44074  124611  35.4%            Apr 20 22:00