encodes a string from ascii to base64

base64_encode

b64_char conv_table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+\\=";
//returns a base 64 string (malloc allocated)
b64_string ascii_to_base_64(ascii_string as, int ascii_char_count)
{	
	//find how many ascii blocks of 3 we have (rounded up)
	int three_blocks_in = (ascii_char_count/3)+(ascii_char_count%3?1:0);
	//from that, how many base 64 blocks?
	int characters_out = three_blocks_in*4;
	//allocate b64 space
	b64_string out_string = malloc(sizeof(b64_char)*(characters_out+1));
	for(int i = 0;i<three_blocks_in;i++)
	{
		b64_char b64A, b64B, b64C, b64D;
		b64A = b64B = b64C = b64D = 0;
		//get first b64 character
		b64A |= ((as[i*3])&0b11111100)>>2;
		b64B |= ((as[i*3])&0b00000011)<<4;
		//if last trio only has first ascii character
		if((i*3)+1 < ascii_char_count)
		{
			b64B |= (as[(i*3)+1]&0b11110000)>>4;
			b64C |= (as[(i*3)+1]&0b00001111)<<2;
		}else{
			//set it equal to 64 - padding
			b64C = b64D = 0b01000000;
		}
		//if last trio only has first two ascii chars
		if((i*3)+2 < ascii_char_count)
		{
			b64C |= (as[(i*3)+2]&0b11000000)>>6;
			b64D |= as[(i*3)+2]&0b00111111;
		}else{
			b64D = 0b01000000;
		}
		out_string[(i*4)] = b64A;
		out_string[(i*4)+1] = b64B;
		out_string[(i*4)+2] = b64C;
		out_string[(i*4)+3] = b64D;
	}
	out_string[characters_out]='\0';
	return out_string;
}