typedefs

typedefs

[Manu Abraham]

Hi,

When one does a

typedef uint8_t array[10];

what does really happen ?


For example, i was looking at some code in the public domain, which had 
it like this ..

u8 is again typedef'd from a unsigned char

#define TS_PACKET_SIZE 188
#define TS_IN_UDP 7

typedef u8 file_ts_packet[TS_PACKET_SIZE];
typedef file_ts_packet udp_packet[TS_IN_UDP];

struct s_own_pcr
{
     int start, end;
     pthread_mutex_t lock;
     file_ts_packet *buf[(TS_BUFFER_SIZE+1)*TS_IN_UDP+1];
};


struct s_in_data
{
     int start, end;
     pthread_mutex_t lock;
     pthread_cond_t notfull;
     pthread_cond_t notempty;
     int b_die;
     udp_packet buf[TS_BUFFER_SIZE+1];
};



So i was wondering what buf would be now. it will be a 1 dimensional array ?
If it is a 1 dimensional array, what could this part of the code 
probably mean .. ?

     /* If we have 2 consecutiv PCR, we can reevaluate slope */
     if( (own_pcr.start != own_pcr.end) &&
         no_discontinuity &&
         !((((u8*) next_pcr = own_pcr.buf[own_pcr.start]))[5] & 0x80))
     {

	....
	....
}

I was wondering what the last condition could probably mean ..


Thanks,
Manu

Re: typedefs

[Giovanni Bajo]

Manu Abraham <abraham.manu@gmail.com> wrote:

> When one does a
>
> typedef uint8_t array[10];
>
> what does really happen ?

This question does not concern the development of the GCC compiler in any way,
so it does not belong here. Please post it to support forums for th eC
language.

Giovanni Bajo

RE: typedefs

[Dave Korn]

Giovanni Bajo wrote:
> Manu Abraham <abraham.manu> wrote:
> 
>> When one does a
>> 
>> typedef uint8_t array[10];
>> 
>> what does really happen ?
> 
> This question does not concern the development of the GCC compiler in any
> way

  ??? Unless, surely, the answer wanted was something along the lines of:

  `The front end creates a tree structure of type ARRAY_TYPE, which has a
TYPE_NAME of "array", a TYPE_DOMAIN member which points to an INTEGER_TYPE
tree struct that has TYPE_MIN_VALUE equal to INTEGER_CST 0 (most likely
integer_zero_node) and TYPE_MAX_VALUE equal to INTEGER_CST 9, and a TREE_TYPE
that points to the INTEGER_TYPE for uint8_t that was created earlier. [ ... ]'

  ...no ?

    cheers,
      DaveK
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