endecode.cpp

.net 方面的开发说明资料。

/*
void
EncodeFileBase64(const char *in, const char *out) {
	// Step 1 : find the size of the source file

	HANDLE file = CreateFile(in, GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
	int source_size = GetFileSize(file, NULL);
	CloseHandle(file);

	// Step 2 : open the source and target file

	FILE *i = fopen(in, "rb");
	FILE *o = fopen(out, "wb");
	
	// Step 3: encode data stream to BASE64
	// The encoded output stream must be represented in lines of no more
	// than 76 characters each.

	BYTE value[3];
	int line_width = 0;

	for (int j = 0; j < source_size / 3; ++j) {
		// read next value

		fread(value, 3, 1, i);

		// convert to 4 6-bit pairs

		fputc(EncodeByte((BYTE)((value[0] & 0xFC) >> 2)), o);
		fputc(EncodeByte((BYTE)(((value[0] & 0x03) << 4) | ((value[1] & 0xF0) >> 4))), o);
		fputc(EncodeByte((BYTE)(((value[1] & 0x0F) << 2) | ((value[2] & 0xC0) >> 6))), o);
		fputc(EncodeByte((BYTE)( value[2] & 0x3F)), o);

		if ((line_width += 4) == 76) {
			line_width = 0;

			fputc('\r', o);
			fputc('\n', o);
		}
	}

	// Step 4: padding
	// Special processing is performed if fewer than 24 bits are available
    // at the end of the data being encoded.  A full encoding quantum is
    // always completed at the end of a body.  When fewer than 24 input bits
    // are available in an input group, zero bits are added (on the right)
    // to form an integral number of 6-bit groups. 

	switch(source_size % 3) {
		case 1 :
		{
			fread(&value, 1, 1, i);

			fputc(EncodeByte((BYTE)((value[0] & 0xFC) >> 2)), o);
			fputc(EncodeByte((BYTE)((value[0] & 0x03) << 4)), o);
			fputc('=', o);
			fputc('=', o);
			break;
		}

		case 2 :
		{
			fread(&value, 2, 1, i);

			fputc(EncodeByte((BYTE)((value[0] & 0xFC) >> 2)), o);
			fputc(EncodeByte((BYTE)(((value[0] & 0x03) << 4) | ((value[1] & 0xF0) >> 4))), o);
			fputc(EncodeByte((BYTE)((value[1] & 0x0F) << 2)), o);
			fputc('=', o);
			break;
		}
	};

	// Step 5: close the files again

	fclose(o);
	fclose(i);
}
*/