# BrainFuck part 6 - 16-bit integers

## Be smart

The previous step demonstrated that our model works fine, but is really slow. Actually, we don't always need 16-bit integers : each operation is more expensive on such integers.

So let's reduce their usage as much as possible: and else flag does not have to be a 16-bit 4-cell-long encoded integer !!!

When we read a number (8-bit)

- First cell is the result : this will be a 16-bit integer
- Second cell is the digit read : always less than 256 (actually, between 48 and 57...)
- then we subtract 48, no need to have 16-bit again for this
- then we add 9 times first integer to second : it seems that second needs to be encoded using 4 cells then. But loop counter (9) doesn't.
- and finally we add second to first

Memory will then be

- Final result: 16-bit
- New digit: 16-bit
- Loop counter: 8-bit
- Result copy: 16-bit

One way to proceed is to use standard operation symbols when manupulating 8-bit values, and their names uppercased while manipulating 16-bit ones.

## Code

```
RIGHT
>>,[ while digit is read
>++++++[-<-------->] remove 48
>+++++++++[ do 9 times
- Decrease counter
LEFT LEFT >> back to result (cell C)
WHILE while not null
MINUS decrease current result
RIGHT PLUS increase current digit
> RIGHT PLUS increase result copy (and goes over counter)
LEFT < LEFT Back to result
LOOP loop
RIGHT > RIGHT go to copy
WHILE
MINUS LEFT < LEFT
PLUS RIGHT > RIGHT
LOOP move
<<< back to counter
]
<< Go to "9 times result plus current digit"
WHILE
MINUS LEFT
PLUS RIGHT
LOOP Store "10 times result plus current digit into first cell
,] read next digit
```

This is the "read integer" code, with some operations on 16 bits and some other on 8 bits. We just have to replace WHILE, MINUS, etc... by the overriden definitions

After that, we can still improve our code by removing things like <>, ><, +- etc... that are (automatically generated) useless instructions.

## Minified version

```
>>>>>>,[>++++++[-<-------->]>+++++++++[-<<<<<<<+>[<-]<[>>[-<+>]<[[->+<]<->]<<]>-[[
-]+>[<-]<[->>-<<<]>>->>>+>+[<-]<[->>+<<<]>>>>>>+>+[<-]<[->>+<<<]<<<<<<<<+>[<-]<[>>
[-<+>]<[[->+<]<->]<<]>-]>>>>>>>>>+>[<-]<[>>[-<+>]<[[->+<]<->]<<]>-[[-]+>[<-]<[->>-
<<<]>>-<<<<<<<<<<+>+[<-]<[->>+<<<]>>>>>>>>>>+>[<-]<[>>[-<+>]<[[->+<]<->]<<]>-]<<]<
<<+>[<-]<[>>[-<+>]<[[->+<]<->]<<]>-[[-]+>[<-]<[->>-<<<]>>-<<<<<+>+[<-]<[->>+<<<]>>
>>>+>[<-]<[>>[-<+>]<[[->+<]<->]<<]>-]>,]
```

Compared to the initial "read integer" source code where all the operations are converted into 16-bit compliant ones, this minified one is 63% smaller.