For this reason, GLSL 4.0 introduces the 'precise' qualifier. I invite
you to take a look at this article.
2014/1/6 Roland Scheidegger srol...@vmware.com:
Am 05.01.2014 01:34, schrieb Maxence Le Doré:
FMA(a,b,c) keeps extra precision (usually 1 more bit of mantissa,
afaik) for the result a*b
I forgot the link :
http://www.geeks3d.com/20120106/precise-qualifier-in-glsl-and-nvidia-geforce-cards/
2014/1/7 Maxence Le Doré maxence.led...@gmail.com:
For this reason, GLSL 4.0 introduces the 'precise' qualifier. I invite
you to take a look at this article.
2014/1/6 Roland Scheidegger
Yes that is certainly related. I'm actually not entirely sure what is
allowed in glsl by default as OpenGL seems to have some lax rules
regarding precision in any case (float calculations not required but
allowed to use denorms, at least earlier versions weren't required to
support Infs neither
FYI, Evergreen has dedicated instructions for both MAD and FMA. FMA
seems to be available on DX11 chips only.
Marek
On Tue, Jan 7, 2014 at 8:20 PM, Roland Scheidegger srol...@vmware.com wrote:
Yes that is certainly related. I'm actually not entirely sure what is
allowed in glsl by default as
Yes, and I guess just about all GPUs can do that.
For llvmpipe we'd be vaguely interested in being able to do opencl-style
MAD with undefined rounding as FMA since (x86) cpus never have MAD but
may have FMA. I am not sure actually though this is ok for d3d10 -
interestingly d3d10 has only MAD for
On Tue, 2014-01-07 at 21:49 +0100, Marek Olšák wrote:
FYI, Evergreen has dedicated instructions for both MAD and FMA. FMA
seems to be available on DX11 chips only.
FWIW, not all evergreen chips support FMA, only high-end chips that
support FP64 (I guess cypress only), according to the isa docs:
Am 05.01.2014 01:34, schrieb Maxence Le Doré:
FMA(a,b,c) keeps extra precision (usually 1 more bit of mantissa,
afaik) for the result a*b and add this to c, to finally produce a
IEEE754 32bit float result.
MAD(a,b,c) product a IEEE754 32bit float product a*b and add it to C.
So, fma can
From: Maxence Le Doré Maxence Le Doré
---
src/gallium/auxiliary/tgsi/tgsi_info.c | 16
src/gallium/auxiliary/tgsi/tgsi_opcode_tmp.h | 6 ++
src/gallium/include/pipe/p_shader_tokens.h | 9 -
3 files changed, 30 insertions(+), 1 deletion(-)
diff --git
How is FMA different from MAD?
Please document the new opcodes in src/gallium/docs/source/tgsi.rst.
Marek
On Sun, Jan 5, 2014 at 12:42 AM, Maxence Le Doré
maxence.led...@gmail.com wrote:
From: Maxence Le Doré Maxence Le Doré
---
src/gallium/auxiliary/tgsi/tgsi_info.c | 16
FMA(a,b,c) keeps extra precision (usually 1 more bit of mantissa,
afaik) for the result a*b and add this to c, to finally produce a
IEEE754 32bit float result.
MAD(a,b,c) product a IEEE754 32bit float product a*b and add it to C.
So, fma can be slightly more accurate. An accuracy that is
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