Fast Bitset in block of data

My draft version is (in my code i need to CLEAR bit in 0xFFFFFFF-filled array, not set);

Code:

align 4
clearBit: ; esi: data, ecx: index of byte
        pushad
        mov       eax, ecx
        ;
        shr       eax, 3        ; /8
        add       esi, eax
        shl       eax, 3        ; *8
        sub       ecx, eax
        ;
        mov       eax, 0xFFFFFF7F
        dec       ecx                      ; needed in my code only
        shr       eax, cl
        and       byte[esi], al
        ;
        popad
ret

also set bit should be:

Code:

align 4
setBit: ; esi: data, ecx: index of byte
        pushad
        mov       eax, ecx
        ;
        shr       eax, 3        ; /8
        add       esi, eax
        shl       eax, 3        ; *8
        sub       ecx, eax
        ;
        mov      eax, 0xFFFFFF80
        dec       ecx                   ; needed in my code only
        shr       eax, cl
        or        byte[esi], al
        ;
        popad
ret

This functions sets bits in linear-style, left-to-right, not in x86 specific low-order bitwise... so setting insex 0 will produce 1000000... real data...

With Revolution code:

Code:

align 4
clearBit_RevolutionMod: ; esi: data, ecx: index of byte
        pushad
        mov       eax, ecx
        ;
        shr       eax, 3        ; /8
        add       esi, eax
        shl       eax, 3        ; *8
        sub       ecx, eax
        ;
        xor        ecx, 7
        bts        byte[esi],ecx
        ;
        popad
ret