[Coco] question C++

[Luis Fernández]

Thanks, I hope to understand this format, which is extremely complex

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> Date: Thu, 22 Mar 2012 14:50:30 +1100

> From: jekent at optusnet.com.au

> To: coco at maltedmedia.com

> Subject: Re: [Coco] question C++

> 

> 

> 

> On 22/03/2012 1:30 AM, Mark McDougall wrote:

> > On 22/03/2012 12:03 AM, Luis Fernández wrote:

> >

> >> ANYONE can tell me the meaning&  here

> >> write_buf (h, 1,&  val);

> >

> > The '&' is the 'address of' operator, so it passes the address of the 

> > 'val' variable.

> >

> >> static void write_buf_const (dmk_handle h, int count, uint8_t val)

> >> {

> >>   while (count--)

> >>     write_buf (h, 1, &val);

> >> }

> >

> > This looks like it writes 'count' number of pad bytes of value 'val'.

> >

> > Regards,

> >

> 

> val is passed on the stack to the write_buf_const procedure.

> I assume dmk_handle is a type definition for a structure pointer type 

> for the buffer.

> "handle" I suspect refers to a pointer type.

> 

> so you might have something like

> 

> struct dmk_buff {

>    unit8_t *inptr;

>    unit8_t *outptr;

>    int count;

>    uint8_t buffer[MAX_BUF_SIZE]]

> };

> 

> typdef struct dmk_buff *dmk_handle;

> 

> although the _t in uint8_t indicates that it is a type definition, and 

> dmk_handle does not indicate it's a type definition, but I assume it is.

> 

> anyway .... what it seems to be doing is passing the address of val to 

> the write_buf routine and the write_buf routine will access val via it's 

> address passed as a pointer value . i.e.

> 

> void write_buf( dmk_handle h, int fill_count, uint8_t *valptr )

> {

>    int i;

> 

>    h->inptr = &h->buffer[h->count];

>    for( i=0; i<fill_count; i++ )

>    {

>      *h->inptr++ = *valptr;

>       h->count++;

>    }

> }

> 

> 

> unit8_count will be 1.

> write_buf will fetch val, using it's address and write it to the buffer 

> via the input pointer

> 

> h->count mean that h is pointing to a structure contain a member 

> variable "count".

> 

> I hope that's right.

> 

> John.

> 

> -- 

> http://www.johnkent.com.au

> http://members.optusnet.com.au/jekent

> 

> 

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