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readme for genwowit.exe
This tool generates two source files for wow32, wowit.c and wowit.h,from the input file wow.it. wow.it contains one pseudo-prototypefor each API we want to have an interpreted thunk for. The programconverts these psuedo-prototypes into interpreted thunk byte streamsin wowit.c's InstrSwamp byte array, and entries in wowit.c'sIntThunkTable which point to the API and the thunk instruction stream.The psuedo-prototypes can have two names separated by an equals sign,indicating the 16-bit API name on the left is thunked to the 32-bitAPI name on the right.
The bytecode instruction streams consist of 0 or more argument conversionopcodes, which don't have the high bit (0x80) set, followed by a returncode conversion opcode, which does have the high bit set.
genwowit tries to keep InstrSwamp as small as possible by pointingmultiple interpreted thunks at the same instruction stream when theyshare prototypes (args & retval types). See for example below howUpdateColors, StartPage, EndPage, and GetTextCharacterExtra alluse the first instruction stream because they all take a GDI handleand return an int.
Further, genwowit will point into the middle of an existing instructionstream if it contains the instruction stream it needs. For example seebelow how the wowit.c IntThunkTable GetRasterizerCaps entry points toInstrSwamp + 0xb, which is 3 bytes into the instruction stream forTextOut, because ignoring the first three TextOut args they have thesame prototype.
An example, here's a tiny wow.it and the wowit.h and wowit.c that result.
----- wow.it beginINT UpdateColors(HGDI);INT StartPage(HGDI);INT EndPage(HGDI);DWORD GetFontData(HGDI, DWORD, DWORD, PTR, DWORD);WORD GetRasterizerCaps(PTR, INT);WORD IsGDIObject=GetObjectType(HGDI);WORD GetTextAlign(HGDI);INT GetTextCharacterExtra(HGDI);INT SetTextCharacterExtra(HGDI, INT);DWORD GetTextColor(HGDI);INT GetTextFace(HGDI, INT, PTR);INT SetTextJustification(HGDI, INT, INT);WORD TextOut(HGDI, INT, INT, PTR, INT);----- wow.it end
here's the output genwowit produces on the console:
Generated wowit.h and wowit.c from wow.it13 thunks, 8 unique instruction streams, 29 instruction bytes, 5 max args.
And the files:
----- wowit.h begin//// wowit.h generated by genwowit.exe from wow.it, DO NOT EDIT.//
#include "intthunk.h"
#define MAX_IT_ARGS 5
#define IT_WORD ( (UCHAR) 0x0 )#define IT_INT ( (UCHAR) 0x1 )#define IT_DWORD ( (UCHAR) 0x2 )#define IT_LPDWORD ( (UCHAR) 0x3 )#define IT_PTR ( (UCHAR) 0x4 )#define IT_PTRORATOM ( (UCHAR) 0x5 )#define IT_HGDI ( (UCHAR) 0x6 )#define IT_HUSER ( (UCHAR) 0x7 )#define IT_COLOR ( (UCHAR) 0x8 )#define IT_HINST ( (UCHAR) 0x9 )#define IT_HICON ( (UCHAR) 0xa )#define IT_16ONLY ( (UCHAR) 0xb )#define IT_32ONLY ( (UCHAR) 0xc )
#define IT_RETMASK ( (UCHAR) 0x80 )#define IT_DWORDRET ( IT_RETMASK | (UCHAR) 0x0 )#define IT_WORDRET ( IT_RETMASK | (UCHAR) 0x1 )#define IT_INTRET ( IT_RETMASK | (UCHAR) 0x2 )#define IT_HGDIRET ( IT_RETMASK | (UCHAR) 0x3 )#define IT_HUSERRET ( IT_RETMASK | (UCHAR) 0x4 )#define IT_ZERORET ( IT_RETMASK | (UCHAR) 0x5 )#define IT_HICONRET ( IT_RETMASK | (UCHAR) 0x6 )#define IT_ONERET ( IT_RETMASK | (UCHAR) 0x7 )#define IT_HPRNDWPRET ( IT_RETMASK | (UCHAR) 0x8 )
#define ITID_UpdateColors 0#define ITID_StartPage 1#define ITID_EndPage 2#define ITID_GetFontData 3#define ITID_GetRasterizerCaps 4#define ITID_IsGDIObject 5#define ITID_GetTextAlign 6#define ITID_GetTextCharacterExtra 7#define ITID_SetTextCharacterExtra 8#define ITID_GetTextColor 9#define ITID_GetTextFace 10#define ITID_SetTextJustification 11#define ITID_TextOut 12
#define ITID_MAX 12----- wowit.h end
----- wowit.c begin//// wowit.c generated by genwowit.exe from wow.it, DO NOT EDIT.//
#include "precomp.h"#pragma hdrstop#define WOWIT_C#include "wowit.h"
CONST BYTE InstrSwamp[] = { /* 0 0x0 */ IT_HGDI, IT_INTRET, /* 1 0x2 */ IT_HGDI, IT_DWORD, IT_DWORD, IT_PTR, IT_DWORD, IT_DWORDRET, /* 2 0x8 */ IT_HGDI, IT_INT, IT_INT, IT_PTR, IT_INT, IT_WORDRET, /* 3 0xe */ IT_HGDI, IT_WORDRET, /* 4 0x10 */ IT_HGDI, IT_INT, IT_INTRET, /* 5 0x13 */ IT_HGDI, IT_DWORDRET, /* 6 0x15 */ IT_HGDI, IT_INT, IT_PTR, IT_INTRET, /* 7 0x19 */ IT_HGDI, IT_INT, IT_INT, IT_INTRET, };
INT_THUNK_TABLEENTRY IntThunkTable[] = { /* 0 */ { (FARPROC) UpdateColors, InstrSwamp + 0x0 }, /* 0 */ /* 1 */ { (FARPROC) StartPage, InstrSwamp + 0x0 }, /* 0 */ /* 2 */ { (FARPROC) EndPage, InstrSwamp + 0x0 }, /* 0 */ /* 3 */ { (FARPROC) GetFontData, InstrSwamp + 0x2 }, /* 1 */ /* 4 */ { (FARPROC) GetRasterizerCaps, InstrSwamp + 0xb }, /* 2 + 3 */ /* 5 */ { (FARPROC) GetObjectType, InstrSwamp + 0xe }, /* 3 */ /* 6 */ { (FARPROC) GetTextAlign, InstrSwamp + 0xe }, /* 3 */ /* 7 */ { (FARPROC) GetTextCharacterExtra, InstrSwamp + 0x0 }, /* 0 */ /* 8 */ { (FARPROC) SetTextCharacterExtra, InstrSwamp + 0x10 }, /* 4 */ /* 9 */ { (FARPROC) GetTextColor, InstrSwamp + 0x13 }, /* 5 */ /* 10 */ { (FARPROC) GetTextFace, InstrSwamp + 0x15 }, /* 6 */ /* 11 */ { (FARPROC) SetTextJustification, InstrSwamp + 0x19 }, /* 7 */ /* 12 */ { (FARPROC) TextOut, InstrSwamp + 0x8 }, /* 2 */ };----- wowit.c end
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