myvtm/Other/win/libfilecryption/asf.cpp

#include "stdafx.h"
#include "asf.h"

uint64_t get_asf_headsize(void* pbuffer, int ilen)
{
	uint64_t uret = 0;
	if (ASF_HEADER_SIZE_LEN != ilen || NULL == pbuffer){
		return uret;
	}
	
	uint32_t ulowbit = 0;
	uint32_t uhighbit = 0;

	memcpy(&ulowbit, pbuffer, sizeof(uint32_t));
	memcpy(&uhighbit, (char*)pbuffer + sizeof(uint32_t), sizeof(uint32_t));

	return (ulowbit + (uhighbit << 32));
}


int construct_asf_headsize(char* pbuffer, int ilen, uint64_t usize)
{
	int iret = -1;
	if (ASF_HEADER_SIZE_LEN > ilen || NULL == pbuffer){
		return iret;
	}

	uint32_t uhighbits = (usize >> 32);
	uint32_t ulowbits = usize;
	if (uhighbits > 0){
		ulowbits = usize - (uhighbits<<32);
	}

	memcpy(pbuffer, &ulowbits, sizeof(uint32_t));
	memcpy(pbuffer+sizeof(uint32_t), &uhighbits, sizeof(uint32_t));

	iret = 0;

	return iret;
}