[BRLTTY] BrlAPI and dot string <-> dot integer conversion

[Yannick PLASSIARD]

On Wed, Dec 13, 2006 at 01:12:56AM +0100, Samuel Thibault wrote:
> Hi,
> 
> Dave proposed to add the following macros and functions to BrlAPI:
> 
> /* convert a dot number ('2' for instance) into a dot bit (BRL_DOT2) */
> #define brlapi_dotNumberToBit(n) ((n) < 1 ? 0 : ((n) > 8 ? 0 : 1 << (n - '1')))
> 
> /* convert a dot bit (BRL_DOT2 for instance) into a dot number ('2') */
> #define brlapi_dotBitToNumber(n) ((n) ? '0' + ffs(n) : 0)
> 
> /* convert a dot number string ("145" for instance) into dot bits
>  * (BRL_DOT1|BRL_DOT4|BRL_DOT5) */
> unsigned char  brlapi_dotNumbersToBits(unsigned char *numbers)
> 
> /* convert dot bits (BRL_DOT1|BRL_DOT4|BRL_DOT5) into a dot string
>  * ("145" for instance), caller should free() the string after use. */
> unsigned char *brlapi_dotBitsToNumbers(unsigned char bits)
> 
> We're a bit reluctant to add such helper functions because
> - they are quite trivial and don't add much value (particularly the
>   macros).
> - the format for dot strings may vary: should it be "134", or "(134)",
>   or "1 34    ", etc. ?
> 
> What do people think about this?  Would these helpers be useful enough
> for adding them to the API ?
> 
Hi:
	I aggree, this could introduce some problems trying to parse and 
guess what the programmer wants us to do.
Moreover, this always depends on the Braille Table used in Brltty (if it 
actually doesn't, it should).
So my suggestions :
- Allow either char or dot writing (as it works now)
- Allow the programmer to put a "temporary" or "permanent" Braille Table 
:
	* the temporary would be used only for the application w:ich 
sent it.
	* The permanent would be used bay all clients, and maybe by the 
Brltty's core.

- If the programmer needs to manipulate dots, (don't know really why but 
let's suppose), I think it would be better to add this in another 
library, or in each program for a start, and if we realize that all API 
clients want to do this, we could decide afterwards to implement it into 
the API (client-side of course).


> Samuel
Yannick
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