On 7/20/08, Ben Dooks <[EMAIL PROTECTED]> wrote: > On Sat, Jul 19, 2008 at 08:46:41PM -0400, Jon Smirl wrote: > > There are a lot places in the i2c API where int is used when the > > parameter can't be negative. For example, there are more.... > > > > /* > > * The master routines are the ones normally used to transmit data to > devices > > * on a bus (or read from them). Apart from two basic transfer functions to > > * transmit one message at a time, a more complex version can be used to > > * transmit an arbitrary number of messages without interruption. > > */ > > extern int i2c_master_send(struct i2c_client *,const char* ,int); > > extern int i2c_master_recv(struct i2c_client *,char* ,int); > > > > /* Transfer num messages. > > */ > > extern int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg > > *msgs, int num); > > > > u8 level; /* nesting level for lockdep */ > > > > > > Wouldn't these generate more efficient code if switched to uints? > > > I'm not sure, most of the time there's not a lot of difference > between the signed and unsigned case. If you can provide an example > of where this is actually true then I would be interested to see...
Assigning between lengths causes sign extended instructions. Mixing signed and unsigned in expressions can cause them too. You get the best code generation by using int or unsigned int as appropriate and supplying the compiler with the correct description of the variable. > > Technically, an unsigned int or simply an unsigned would be a > reasonable change given that you can't really have a minus number > of transfers. > > > -- > Ben ([EMAIL PROTECTED], http://www.fluff.org/) > > 'a smiley only costs 4 bytes' > -- Jon Smirl [EMAIL PROTECTED] _______________________________________________ i2c mailing list [email protected] http://lists.lm-sensors.org/mailman/listinfo/i2c
