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Sorry guys, I'm VERY rusty on my Assembler, haven't been here for a long time!
Tried searching for my answers, but didn't find anything useful quickly and easily!

I'm working in OpenGL (and C/C++, Win32), for some performance reasons, I want to find a more direct approach to certain function calls.

Background: OpenGL32.dll has loads of functions. Many functions accept a different data type, handled by a different function, but accomplish the same thing. eg. glTexCoord2f and glTexCoord2d are identical except the one accepts a float (function ends with f) and the other a double (function ends with d). But one function will likely call the other, or they might both jump and call some other function. I want to know where they go, what is the final function, so I can skip a few jumps etc. Also, I know these are implementation specific, so ATI drivers might map differently than nVidia. And Win32 might be different to linux. But Imight be able to find a trend and I just want to know!

So, I disassembled OpenGL32.dll, but since I'm rusty, I'm kinda lost a bit.
Using dumppe I get to:

5ED02BD8                    glTexCoord2d:
5ED02BD8 64A118000000          mov    eax,fs:[18h]
5ED02BDE FFA0C4080000          jmp    dword ptr
5ED02BF0                    glTexCoord2f:
5ED02BF0 64A118000000          mov    eax,fs:[18h]
5ED02BF6 FFA0CC080000          jmp    dword ptr

Obviously a lookup table! Where to now?

Thanx!

Accept that a lookup table is being used and that you can't do anything about it :)

The implementations can change from driver to driver, from version to version. You're optimizing at a wrong level; premature optimization is the root of all evil.

well obvioulsy some other problems :(
i googled downlaoded the 300 kb odd opengl32.dll and disassembled it to find it entirely different :(

7D11FED4 glTexCoord2dv           MOV EAX,DWORD PTR FS:[18]
7D11FEDA                         MOV EDX,EAX
7D11FEDC                         ADD EDX,DWORD PTR DS:[7D1A4D70]
7D11FEE2                         MOV EDX,DWORD PTR DS:
7D11FEE4                         JMP DWORD PTR DS:
7D11FEEA                         MOV EAX,EAX
7D11FEEC glTexCoord2f            MOV EAX,DWORD PTR FS:[18]
7D11FEF2                         MOV EDX,EAX
7D11FEF4                         ADD EDX,DWORD PTR DS:[7D1A4D70]
7D11FEFA                         MOV EDX,DWORD PTR DS:
7D11FEFC                         JMP DWORD PTR DS:               ;  OPENGL32.7D11F388
7D11FF02                         MOV EAX,EAX
7D11FF04 glTexCoord2fv           MOV EAX,DWORD PTR FS:[18]
7D11FF0A                         MOV EDX,EAX
7D11FF0C                         ADD EDX,DWORD PTR DS:[7D1A4D70]
7D11FF12                         MOV EDX,DWORD PTR DS:
7D11FF14                         JMP DWORD PTR DS:
7D11FF1A                         MOV EAX,EAX
7D11FF1C glTexCoord2i            MOV EAX,DWORD PTR FS:[18]

00460078  88 F3 11 7D 80 F3 11 7D 83 F3 11 7D 8D F3 11 7D  ??}??}??}??}
00460088  88 F3 11 7D 83 F3 11 7D 83 F3 11 7D 83 F3 11 7D  ??}??}??}??}
00460098  A1 F3 11 7D 8D F3 11 7D 83 F3 11 7D 9C F3 11 7D  ??}??}??}??}
004600A8  83 F3 11 7D 8D F3 11 7D 83 F3 11 7D 8D F3 11 7D  ??}??}??}??}
004600B8  83 F3 11 7D 8D F3 11 7D 83 F3 11 7D 8D F3 11 7D  ??}??}??}??}
004600C8  83 F3 11 7D 8D F3 11 7D 83 F3 11 7D 8D F3 11 7D  ??}??}??}??}
004600D8  83 F3 11 7D 92 F3 11 7D 83 F3 11 7D A6 F3 11 7D  ??}??}??}??}

7D11F388                         XOR EAX,EAX
7D11F38A                         RETN 8

well that constant there for vftable gets filled here

7D1120D9                         LEA ECX,DWORD PTR DS: <-----
7D1120E0                         PUSH 4                                   ; /Protect = PAGE_READWRITE
7D1120E2                  ---->MOV DWORD PTR DS:[7D1A4D70],ECX          ; |
7D1120E8                         PUSH 102000                              ; |AllocationType = MEM_RESERVE|MEM_TOP_DOWN
7D1120ED                         PUSH 5FA00                               ; |Size = 5FA00 (391680.)
7D1120F2                         PUSH 0                                   ; |Address = NULL
7D1120F4                         CALL DWORD PTR DS:[<&KERNEL32.VirtualAll>; \VirtualAlloc

so its pretty straight forward it seems