Yes, that's a very good idea. The implementation would be fast, furthermore
the implementation body would be small, so it could be an inline function in
u_format.h, therefore allowing the compiler to coalesce multiple calls too.
It implies that the u_format_table.py script needs to parse
src/gallium/include/pipe/p_format.h to obtain the actual values of PIPE_FORMAT
enums, so it knows which format goes on which entry of the table, but that's
certainly doable.
Fair enough. Ignore my comment about util_format_description() for now, and
we'll do this in a follow on change.
Jose
----- Original Message -----
> Wouldn't it be easier to just make util_format_description table-based
> and inline instead of switch-based? Something like:
>
> return format < PIPE_FORMAT_COUNT ? table[format] : NULL;
>
> Marek
>
> On Mon, Jun 24, 2013 at 10:12 AM, Jose Fonseca <jfons...@vmware.com> wrote:
> >
> >
> > ----- Original Message -----
> >> ---
> >> src/gallium/auxiliary/util/u_format.c | 14 ++++++++++++++
> >> src/gallium/auxiliary/util/u_format.h | 3 +++
> >> src/mesa/state_tracker/st_cb_drawpixels.c | 6 ++++++
> >> 3 files changed, 23 insertions(+)
> >>
> >> diff --git a/src/gallium/auxiliary/util/u_format.c
> >> b/src/gallium/auxiliary/util/u_format.c
> >> index 9bdc2ea..b70c108 100644
> >> --- a/src/gallium/auxiliary/util/u_format.c
> >> +++ b/src/gallium/auxiliary/util/u_format.c
> >> @@ -131,6 +131,20 @@ util_format_is_pure_uint(enum pipe_format format)
> >> return (desc->channel[i].type == UTIL_FORMAT_TYPE_UNSIGNED &&
> >> desc->channel[i].pure_integer) ? TRUE : FALSE;
> >> }
> >>
> >> +boolean
> >> +util_format_is_snorm(enum pipe_format format)
> >> +{
> >> + const struct util_format_description *desc =
> >> util_format_description(format);
> >> + int i;
> >> +
> >> + i = util_format_get_first_non_void_channel(format);
> >> + if (i == -1)
> >> + return FALSE;
> >> +
> >> + return desc->channel[i].type == UTIL_FORMAT_TYPE_SIGNED &&
> >> + !desc->channel[i].pure_integer &&
> >> + desc->channel[i].normalized;
> >> +}
> >
> > This will give wrong results for mixed formats -- containing a mixture of
> > SIGNED and UNSIGNED normalized types. You can avoid that by adding this
> > statement
> >
> > if (desc->is_mixed) return FALSE at the start.
> >
> > I think a comment would be good too -- something like "Returns true if all
> > non-void channels are normalized signed."
> >
> > This is not your fault, but it is disappointing to see the proliferation of
> > redundant util_format_description() calls in these helpers.
> > util_format_description is not cost free, and st_CopyPixels and friends
> > keep calling it over and over again. I don't think it is hard to call
> > util_format_description() once, and then pass the format_desc pointers
> > around, but once we start on the other route is hard to back out. But as
> > they say -- when you're in a hole, the first thing to do is stop digging
> > --, so I think we should just stop adding new helper functions to util
> > u_format that take enum format instead of util_format_description.
> >
> > Jose
> >
> >>
> >> boolean
> >> util_format_is_luminance_alpha(enum pipe_format format)
> >> diff --git a/src/gallium/auxiliary/util/u_format.h
> >> b/src/gallium/auxiliary/util/u_format.h
> >> index 4cace6a..ccb7f92 100644
> >> --- a/src/gallium/auxiliary/util/u_format.h
> >> +++ b/src/gallium/auxiliary/util/u_format.h
> >> @@ -622,6 +622,9 @@ util_format_is_pure_sint(enum pipe_format format);
> >> boolean
> >> util_format_is_pure_uint(enum pipe_format format);
> >>
> >> +boolean
> >> +util_format_is_snorm(enum pipe_format format);
> >> +
> >> /**
> >> * Check if the src format can be blitted to the destination format with
> >> * a simple memcpy. For example, blitting from RGBA to RGBx is OK, but
> >> not
> >> diff --git a/src/mesa/state_tracker/st_cb_drawpixels.c
> >> b/src/mesa/state_tracker/st_cb_drawpixels.c
> >> index 38563d5..0b5198a 100644
> >> --- a/src/mesa/state_tracker/st_cb_drawpixels.c
> >> +++ b/src/mesa/state_tracker/st_cb_drawpixels.c
> >> @@ -1549,6 +1549,7 @@ st_CopyPixels(struct gl_context *ctx, GLint srcx,
> >> GLint
> >> srcy,
> >>
> >> if (!screen->is_format_supported(screen, srcFormat,
> >> st->internal_target,
> >> 0,
> >> srcBind)) {
> >> + /* srcFormat is non-renderable. Find a compatible renderable
> >> format.
> >> */
> >> if (type == GL_DEPTH) {
> >> srcFormat = st_choose_format(st, GL_DEPTH_COMPONENT, GL_NONE,
> >> GL_NONE, st->internal_target, 0,
> >> @@ -1572,6 +1573,11 @@ st_CopyPixels(struct gl_context *ctx, GLint srcx,
> >> GLint srcy,
> >> GL_NONE, st->internal_target, 0,
> >> srcBind, FALSE);
> >> }
> >> + else if (util_format_is_snorm(srcFormat)) {
> >> + srcFormat = st_choose_format(st, GL_RGBA16_SNORM, GL_NONE,
> >> + GL_NONE, st->internal_target, 0,
> >> + srcBind, FALSE);
> >> + }
> >> else {
> >> srcFormat = st_choose_format(st, GL_RGBA, GL_NONE,
> >> GL_NONE, st->internal_target, 0,
>
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