Help File:Big endian 4 byte

---

alloc(TypeName,256)

alloc(ByteSize,4)

alloc(ConvertRoutine,1024)

alloc(ConvertBackRoutine,1024)

TypeName:

db '4 Byte Big Endian',0

ByteSize:

dd 4

//The convert routine should hold a routine that converts the data to an integer (in eax)

//function declared as: stdcall int ConvertRoutine(unsigned char *input);

//Note: Keep in mind that this routine can be called by multiple threads at the same time.

ConvertRoutine:

//jmp dllname.functionname

[64-bit]

//or manual:

//parameters: (64-bit)

//rcx=address of input

xor eax,eax

mov eax,[rcx] //eax now contains the bytes 'input' pointed to

bswap eax //convert to big endian

ret

[/64-bit]

[32-bit]

//jmp dllname.functionname

//or manual:

//parameters: (32-bit)

push ebp

mov ebp,esp

//[ebp+8]=input

//example:

mov eax,[ebp+8] //place the address that contains the bytes into eax

mov eax,[eax] //place the bytes into eax so it's handled as a normal 4 byte value

bswap eax

pop ebp

ret 4

[/32-bit]

//The convert back routine should hold a routine that converts the given integer back to a row of

bytes (e.g when the user wats to write a new value)

//function declared as: stdcall void ConvertBackRoutine(int i, unsigned char *output);

ConvertBackRoutine:

//jmp dllname.functionname

//or manual:

[64-bit]

//parameters: (64-bit)

//ecx=input

//rdx=address of output

//example:

bswap ecx //convert the little endian input into a big endian input

mov [rdx],ecx //place the integer the 4 bytes pointed to by rdx

ret

[/64-bit]

[32-bit]

//parameters: (32-bit)

push ebp

mov ebp,esp

//[ebp+8]=input

//[ebp+c]=address of output

//example:

push eax

push ebx

mov eax,[ebp+8] //load the value into eax

mov ebx,[ebp+c] //load the address into ebx

//convert the value to big endian

bswap eax

mov [ebx],eax //write the value into the address

pop ebx

pop eax

pop ebp

ret 8

[/32-bit]