Subject: Re: bus.h style question
To: Jonathan Stone <jonathan@dsg.stanford.edu>
From: Jason Thorpe <thorpej@nas.nasa.gov>
List: tech-kern
Date: 08/21/1997 06:59:18
On Wed, 20 Aug 1997 03:33:11 -0700
Jonathan Stone <jonathan@DSG.Stanford.EDU> wrote:
> Err, actually I thought I was proposing semantics more like
>
> #define bus_space_read_swapped_2 (t, h, o) \
> NTOHS(bus_space_read_2(t, h, (o))
>
> #define bus_space_read_swapped_4 (t, h, o) \
> NTOHL(bus_space_read_2(t, h, (o))
UGH! NO! The methods should have much more abstracted names than that,
and this doesn't even do the right thing!
Here is what the semantics, IMO, should be:
bus_space_{read,write}* - value is read from/written to bus space.
If the bus's "native" byte order is different from the CPU's, any
appropriate byte swapping _will_ occur.
(new entry points)
bus_space_stream_{read,write}* - value is read from/written to bus
space. The values are treated as octet streams, thus bypassing
any byte swapping mechanisms. Useful for e.g. 16-bit PIO access
to NE-2000 ethernet cards, manipulating VGA frame buffer data, etc.
Jason R. Thorpe thorpej@nas.nasa.gov
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