84 lines
3.5 KiB
Plaintext
84 lines
3.5 KiB
Plaintext
This is intend to be a document to help new developers get started.
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Existing developers should feel free to add there comments.
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SUBMITTING YOUR WORK:
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Submissions of code for inclussion into Wine should be sent to
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wine-new@amscons.com (Bob Amstadt). You MUST provide a suitable
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ChangeLog entry for any work that you submit. I prefer new code
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to be submitted as unified diffs (diff -u) off of the latest release.
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Releases are every Tuesday evening (approximately 17:00 PST or
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Wednesday 01:00 GMT).
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MEMORY AND SEGMENTS:
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NE (Win16) executables consist of multiple segments. The Wine loader
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loads each segment into a unique location the Wine processes memory
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and assigns a selector to that segment. To make address conversion
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simpler, Wine loads the segments in such a way that the segmented
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address (16:16) is stored in memory the same way as the 32-bit linear
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address. For example, the segmented address 1237:89AB can be at the
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address 0x123789AB in the Wine process space.
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This also implies that a Win16 program cannot access any arbitrary
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memory location. If a pointer needs to be returned to a Win16 program,
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then the memory block must be allocated using either GlobalAlloc()
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or HEAP_Alloc(). The HEAP_* functions are faster than the Global*
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functions but are only capable of managing a 64k memory block. The
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HEAP_* functions are used to implement local heaps. Wine should
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never call Local* functions. These functions are reserved for use
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by Win16 programs only!
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The following code fragment should be used to establish a new Wine
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local heap:
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#include "heap.h"
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#define MY_HEAP_SIZE 0x10000 /* Must be <= 64k */
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int MyHeapHandle;
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void *MyHeapBase;
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MDESC *MyHeap;
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...
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int InitMyHeap()
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{
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MyHeapHandle = GlobalAlloc(GMEM_FIXED, MY_HEAP_SIZE);
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if (MyHeapHandle == 0)
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return -1;
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MyHeapBase = GlobalLock(MyHeapHandle);
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HEAP_Init(&MyHeap, MyHeapBase, MY_HEAP_SIZE);
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return 0;
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}
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Memory blocks greater than 64 kilobytes in length must be allocated
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using GlobalAlloc(). Because of our special memory mapping, GlobalLock()
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cannot be used to obtain the address of a linearly accessible memory
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block that is greater than 64kB in length. Instead GlobalLinearLock()
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should be used. The inverse function GlobalLinearUnlock() must be
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called before the block can be freed with GlobalFree().
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API ENTRY POINTS:
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Because Win16 programs use a 16-bit stack and because they can only
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call 16:16 addressed functions, all API entry points must be at low
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address offsets and must have the arguments translated and moved to
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Wines 32-bit stack. This task is handled by the code in the "if1632"
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directory. To define a new API entry point handler you must place a
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new entry in the appropriate API specification file. These files are
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named *.spec. For example, the API specification file for the USER DLL
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is contained in the file user.spec. These entries are processed by
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the "build" program to create dll_*.s and dll_tab_*.c. The dll_*.s
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files contain the entry point code for each API call, and the dll_tab_*.s
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files contain tables used by relay.c to translate arguments and transfer
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control to the proper handler. The format of the *.spec files is
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documented in the file "tools/build-spec.txt".
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REGISTER FUNCTIONS:
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Some functions are defined as type "register" in the DLL specification files.
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Inorder to return values in the registers to the WIN16 program, the handler
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function must exit by calling ReturnFromRegisterFunc(). Look at the function
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DOS3Call() for an example of how this works.
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