#include <process.h>
#include <conio.h>
#include <stdio.h>
#include <fcntl.h>
#include <io.h>
#include <sys\types.h>
#include <sys\stat.h>

	//How I figured out where to patch the Shadow Warrior executable:
	//
	//   (Numbers are from the Shadow Warrior v1.2 shareware executable)
	//
	//Step 1: Look for this unique sequence of bytes in the EXE:
	//
	//         ;(Somewhere inside JS_ProcessEchoSpot function in jsector.c)
	//      C13A1:  66 3D C8 00            cmp ax, 200
	//      C13A5:  7E 05                  jle l1
	//      C13A7:  B8 C8 00 00 00         mov eax, 200
	//      C13AC:  66 3D 64 00        l1: cmp ax, 100
	//      C13B0:  7D 05                  jge l2
	//      C13B2:  B8 64 00 00 00         mov eax, 100
	//      C13B7:  98                 l2: cwde
	//      C13B8:  B3 01                  mov bl, 1
	//      C13BA:  E8 D9 9A FD FF         call COVER_SetReverb
	//      C13BF:  88 1C 24 89            mov [esp], bl
	//
	//   Try looking for "66 3D C8 00 7E 05" - it's unlikely to have duplicates
	//
	//Step 2: Find the target of the COVER_SetReverb call. You can identify the
	//    call statement because it will be the only byte nearby that's an E8.
	//    The 4 numbers after it make up the RELATIVE jump. Add this value to
	//    the position of the byte RIGHT AFTER the 5-byte call statement. Here's
	//    how you do the calculation for my example:
	//
	//      C13BF + FFFD9AD9 = 9AE98
	//
	//   That's all you need - 9AE98 is the magic offset!
	//
	//   Just for fun, let's see what's there:
	//
	//                    COVER_SetReverb:
	//      9AE98:  83 3D CC 54 0A 00 08   cmp dword ptr [variable], 8
	//      9AE9F:  74 F5                  je l3    ;points to C3 (ret)
	//      9AEA1:  E9 4E 5F 0A 00         jmp l4   ;jump to FX_SetReverb?
	//
	//Step 3: Replace the first byte of the COVER_SetReverb function with a
	//   return (C3)
	//
	//      9AE98:  C3                     ret
	//      9AE99:  3D CC 54 ...           ;invalid opcodes, but who cares!
	//
	//----------------------------------------------------------------------
	//
	//   Here are the values for Shadow Warrior v1.2 (registered):
	//
	//      C26F6:  E8 11 91 FD FF         call COVER_SetReverb
	//
	//                    COVER_SetReverb:
	//      9B80C:  83 3D 80 AA 0B 00 08   cmp dword ptr [variable], 8

main ()
{
	int fil, i;
	long fileng, offs;
	unsigned char ch, tempbuf[8];

	puts("");
	puts("SWSNDFX for Shadow Warrior               by Kenneth Silverman (04/28/2000)");
	puts("");
	puts("This program fixes a sound crashing bug in SW.EXE that occurs on newer");
	puts("   (PCI?) sound cards. If the game crashes when going underwater or going");
	puts("   on the train tracks of the 1st level, then you've found the right program.");
	puts("");
	puts("Please note: This program supports ONLY these versions of Shadow Warrior:");
	puts("   v1.2 Shareware and Registered");
	puts("");
	puts("   None of the 3dfx versions are currently supported.");
	puts("");
	puts("Also, be aware that as a side effect, reverberation will be disabled.");
	puts("");
	puts("Do you want to continue with patching SW.EXE? (Y/N)");

	do
	{
		ch = getch();
	} while ((ch != 'n') && (ch != 'N') && (ch != 'y') && (ch != 'Y') && (ch != 27));
	if ((ch == 'n') || (ch == 'N') || (ch == 27))
	{
		puts("Operation aborted");
		exit(0);
	}

	if ((fil = open("SW.EXE",O_BINARY|O_RDWR,S_IREAD)) == -1)
		{ puts("ERROR 1: Can't read SW.EXE: Make sure it is in the current directory."); exit(0); }
	fileng = filelength(fil);

	offs = -1;
	if (fileng == 2324603) offs = 0x9ae98;   //1.2 (shareware)
	if (fileng == 2323389) offs = 0x9b80c;   //1.2 (registered)
	if (offs == -1) { puts("ERROR 2: SW.EXE unrecognized or not currently supported."); exit(0); }

	lseek(fil,offs,SEEK_SET);
	read(fil,tempbuf,8);
	close(fil);

	if (fileng == 2324603)
	{
		if ((tempbuf[0] == 0xc3) && (tempbuf[1] == 0x3d) && (tempbuf[2] == 0xcc) &&
			 (tempbuf[3] == 0x54) && (tempbuf[4] == 0x0a) && (tempbuf[5] == 0x00) &&
			 (tempbuf[6] == 0x08) && (tempbuf[7] == 0x74))
		{
			puts("This sound patch has already been applied to SW.EXE.");
			exit(0);
		}
	
		if ((tempbuf[0] != 0x83) || (tempbuf[1] != 0x3d) || (tempbuf[2] != 0xcc) ||
			 (tempbuf[3] != 0x54) || (tempbuf[4] != 0x0a) || (tempbuf[5] != 0x00) ||
			 (tempbuf[6] != 0x08) || (tempbuf[7] != 0x74))
		{
			puts("ERROR 3: SW.EXE unrecognized, or not currently supported.");
			exit(0);
		}
	}

	if (fileng == 2323389)
	{
		if ((tempbuf[0] == 0xc3) && (tempbuf[1] == 0x3d) && (tempbuf[2] == 0x80) &&
			 (tempbuf[3] == 0xaa) && (tempbuf[4] == 0x0b) && (tempbuf[5] == 0x00) &&
			 (tempbuf[6] == 0x08) && (tempbuf[7] == 0x74))
		{
			puts("This sound patch has already been applied to SW.EXE.");
			exit(0);
		}
	
		if ((tempbuf[0] != 0x83) || (tempbuf[1] != 0x3d) || (tempbuf[2] != 0x80) ||
			 (tempbuf[3] != 0xaa) || (tempbuf[4] != 0x0b) || (tempbuf[5] != 0x00) ||
			 (tempbuf[6] != 0x08) || (tempbuf[7] != 0x74))
		{
			puts("ERROR 3: SW.EXE unrecognized, or not currently supported.");
			exit(0);
		}
	}

		//Actually modify the exe here:
	if ((fil = open("SW.EXE",O_BINARY|O_RDWR,S_IWRITE)) == -1)
		{ puts("ERROR 4: Can't write to SW.EXE: Make sure it has write priviledges."); exit(0); }
	lseek(fil,offs,SEEK_SET);
	tempbuf[0] = 0xc3;
	write(fil,tempbuf,1);
	close(fil);
	puts("SUCCESS! SW.EXE has been patched to prevent the sound crashing bug.");
}