[Mesa-dev] [PATCH 3/8] compiler/blob: Rework blob_reserve_bytes

[Jason Ekstrand]

On Fri, Sep 22, 2017 at 7:18 AM, Connor Abbott <cwabbott0 at gmail.com> wrote:

> I like the version I wrote a little better. The main difference is
> that instead of the alignment parameter, I added a
> blob_reserve_intptr() function to match blob_read_intptr() and
> blob_write_intptr(). I also updated the doxygen comment for the
> function, and had a little more descriptive commit message:
> https://cgit.freedesktop.org/~cwabbott0/mesa/commit/?h=nir-serialize&id=
> f2e1e0df8d0d24afc072bcd47d86338436b3fdc2
>

I think I like that better too


> On Fri, Sep 15, 2017 at 9:39 PM, Jason Ekstrand <jason at jlekstrand.net>
> wrote:
> > This commit primarily makes two changes.  First, blob_reserve_bytes now
> > takes an alignment parameter.  Second, we now return an offset into the
> > blob instead of a pointer and leave the pointer arithmetic to the
> > caller.  This way you can call blob_reserve_bytes, emit a bunch more
> > stuff, and then come back and fill in the reserved data.
> > ---
> >  src/compiler/blob.c                 | 14 ++++++++------
> >  src/compiler/blob.h                 |  8 ++++----
> >  src/compiler/glsl/tests/blob_test.c |  7 ++++---
> >  3 files changed, 16 insertions(+), 13 deletions(-)
> >
> > diff --git a/src/compiler/blob.c b/src/compiler/blob.c
> > index 3c4aed8..7324a6b 100644
> > --- a/src/compiler/blob.c
> > +++ b/src/compiler/blob.c
> > @@ -139,18 +139,20 @@ blob_write_bytes(struct blob *blob, const void
> *bytes, size_t to_write)
> >     return true;
> >  }
> >
> > -uint8_t *
> > -blob_reserve_bytes(struct blob *blob, size_t to_write)
> > +size_t
> > +blob_reserve_bytes(struct blob *blob, size_t to_write, size_t align)
> >  {
> > -   uint8_t *ret;
> > +   size_t offset;
> > +
> > +   align_blob(blob, align);
> >
> >     if (! grow_to_fit (blob, to_write))
> > -      return NULL;
> > +      return (size_t)-1;
> >
> > -   ret = blob->data + blob->size;
> > +   offset = blob->size;
> >     blob->size += to_write;
> >
> > -   return ret;
> > +   return offset;
> >  }
> >
> >  bool
> > diff --git a/src/compiler/blob.h b/src/compiler/blob.h
> > index 940c81e..e1f7fe7 100644
> > --- a/src/compiler/blob.h
> > +++ b/src/compiler/blob.h
> > @@ -113,11 +113,11 @@ blob_write_bytes(struct blob *blob, const void
> *bytes, size_t to_write);
> >   * that is not aware of the blob API, (so that blob_write_bytes cannot
> be
> >   * called).
> >   *
> > - * \return A pointer to space allocated within \blob to which \to_write
> bytes
> > - * can be written, (or NULL in case of any allocation error).
> > + * \return The offset into \blob at which \to_write bytes can be
> written, (or
> > + * NULL in case of any allocation error).
> >   */
> > -uint8_t *
> > -blob_reserve_bytes(struct blob *blob, size_t to_write);
> > +size_t
> > +blob_reserve_bytes(struct blob *blob, size_t to_write, size_t align);
> >
> >  /**
> >   * Overwrite some data previously written to the blob.
> > diff --git a/src/compiler/glsl/tests/blob_test.c
> b/src/compiler/glsl/tests/blob_test.c
> > index df0e91a..e82ceb1 100644
> > --- a/src/compiler/glsl/tests/blob_test.c
> > +++ b/src/compiler/glsl/tests/blob_test.c
> > @@ -120,7 +120,7 @@ test_write_and_read_functions (void)
> >  {
> >     struct blob *blob;
> >     struct blob_reader reader;
> > -   uint8_t *reserved;
> > +   size_t reserved_offset;
> >     size_t str_offset, uint_offset;
> >     uint8_t reserve_buf[sizeof(reserve_test_str)];
> >
> > @@ -130,8 +130,9 @@ test_write_and_read_functions (void)
> >
> >     blob_write_bytes(blob, bytes_test_str, sizeof(bytes_test_str));
> >
> > -   reserved = blob_reserve_bytes(blob, sizeof(reserve_test_str));
> > -   memcpy(reserved, reserve_test_str, sizeof(reserve_test_str));
> > +   reserved_offset = blob_reserve_bytes(blob, sizeof(reserve_test_str),
> 1);
> > +   memcpy(blob->data + reserved_offset,
> > +          reserve_test_str, sizeof(reserve_test_str));
> >
> >     /* Write a placeholder, (to be replaced later via overwrite_bytes) */
> >     str_offset = blob->size;
> > --
> > 2.5.0.400.gff86faf
> >
> > _______________________________________________
> > mesa-dev mailing list
> > mesa-dev at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/mesa-dev
>
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