Re: [PATCH] SPU use a 16 byte fpos_t

[Jeff Johnston <jjohnstn at redhat dot com>]

Patrick Mansfield wrote:
> fpos_t is 12 bytes for 32 bit ppc glibc, and 16 bytes for 64 bit.
>
> Currently SPU newlib uses 4 bytes for fpos_t. This is always a problem
> with 64 bit ppc, since the fgetpos() assist call writes 8 bytes back for
> the offset, and is a potential problem with 32 bit ppc.
>
> So for SPU always use 16 bytes for fpos_t and also make currently unused
> (in SPU) _fpos64_t 16 bytes.

Patrick,

  This needs to be cleaned up.  Not your fault, but I don't want cpu 
checks in sys/reent.h and I don't think that _fpos_t should be magically 
defined in sys/reent.h.  The following proposal makes this change and 
others easy for you to do.  It is pretty straightforward.

  So, this is what I propose:

  1. copy machine/_types.h to machine/_default_types.h
  2. make machine/_types.h simply include machine/_default_types.h
  3. have sys/_types.h include machine/_types.h
  4. have sys/_types.h look for flags before defining _ types.  For
     example, #ifndef _OFF_T_DEFINED).  You need to add
     _fpos_t and  _fpos64_t default defs which weren't there previously
  5. create an machine/spu/machine/_types.h which defines all of these
     to your liking...also set the flags on so sys/_types.h won't try
     and define them
  6. remove _fpos_t and _fpos64_t defs from sys/reent.h

  This will be clean and allow other platforms to do tweaking as
desired without cluttering up the common headers.

  Comments?

-- Jeff J.

> newlib ChangeLog:
>
> 2007-09-05 Patrick Mansfield <patmans@us.ibm.com>
>
> 	* libc/include/sys/reent.h: For SPU use a _fpos_t and _fpos64_t with
> 	sizes of 16 bytes.
>
> Index: src/newlib/libc/include/sys/reent.h
> ===================================================================
> --- src.orig/newlib/libc/include/sys/reent.h
> +++ src/newlib/libc/include/sys/reent.h
> @@ -112,6 +112,19 @@ struct __sbuf {
>   * so we use _fpos_t instead.
>   */
>  
> +#ifdef __SPU__
> +/*
> + * Requires that the size be large enough to store a 64 bit ppc glibc
> + * fpos_t of 16 bytes.
> + */
> +typedef struct {
> +  char __pos[16];
> +} _fpos_t;
> +#ifdef __LARGE64_FILES
> +typedef _fpos_t _fpos64_t;
> +#endif
> +
> +#else
>  typedef long _fpos_t;		/* XXX must match off_t in <sys/types.h> */
>  				/* (and must be `long' for now) */
>  
> @@ -119,6 +132,8 @@ typedef long _fpos_t;		/* XXX must match
>  typedef _off64_t _fpos64_t;
>  #endif
>  
> +#endif
> +
>  /*
>   * Stdio state variables.
>   *