[Mesa-dev] [PATCH 3/6] glsl: move half<->float convertion to util
Jason Ekstrand
jason at jlekstrand.net
Sun Oct 11 21:47:08 PDT 2015
On Oct 10, 2015 12:09 PM, "Matt Turner" <mattst88 at gmail.com> wrote:
>
> On Sat, Oct 10, 2015 at 11:47 AM, Rob Clark <robdclark at gmail.com> wrote:
> > From: Rob Clark <robclark at freedesktop.org>
> >
> > Needed in NIR too, so move out of mesa/main/imports.c
> >
> > Signed-off-by: Rob Clark <robclark at freedesktop.org>
> > ---
> > src/glsl/Makefile.am | 1 +
> > src/mesa/main/imports.c | 148 --------------------------------------
> > src/mesa/main/imports.h | 38 ++++++++--
> > src/util/Makefile.sources | 2 +
> > src/util/convert.c | 179
++++++++++++++++++++++++++++++++++++++++++++++
> > src/util/convert.h | 43 +++++++++++
> > 6 files changed, 259 insertions(+), 152 deletions(-)
> > create mode 100644 src/util/convert.c
> > create mode 100644 src/util/convert.h
> >
> > diff --git a/src/glsl/Makefile.am b/src/glsl/Makefile.am
> > index 3265391..347919b 100644
> > --- a/src/glsl/Makefile.am
> > +++ b/src/glsl/Makefile.am
> > @@ -160,6 +160,7 @@ glsl_compiler_SOURCES = \
> > glsl_compiler_LDADD = \
> > libglsl.la \
> > $(top_builddir)/src/libglsl_util.la \
> > + $(top_builddir)/src/util/libmesautil.la \
> > $(PTHREAD_LIBS)
> >
> > glsl_test_SOURCES = \
> > diff --git a/src/mesa/main/imports.c b/src/mesa/main/imports.c
> > index 350e675..230ebbc 100644
> > --- a/src/mesa/main/imports.c
> > +++ b/src/mesa/main/imports.c
> > @@ -307,154 +307,6 @@ _mesa_bitcount_64(uint64_t n)
> > }
> > #endif
> >
> > -
> > -/**
> > - * Convert a 4-byte float to a 2-byte half float.
> > - *
> > - * Not all float32 values can be represented exactly as a float16
value. We
> > - * round such intermediate float32 values to the nearest float16. When
the
> > - * float32 lies exactly between to float16 values, we round to the one
with
> > - * an even mantissa.
> > - *
> > - * This rounding behavior has several benefits:
> > - * - It has no sign bias.
> > - *
> > - * - It reproduces the behavior of real hardware: opcode F32TO16 in
Intel's
> > - * GPU ISA.
> > - *
> > - * - By reproducing the behavior of the GPU (at least on Intel
hardware),
> > - * compile-time evaluation of constant packHalf2x16 GLSL
expressions will
> > - * result in the same value as if the expression were executed on
the GPU.
> > - */
> > -GLhalfARB
> > -_mesa_float_to_half(float val)
> > -{
> > - const fi_type fi = {val};
> > - const int flt_m = fi.i & 0x7fffff;
> > - const int flt_e = (fi.i >> 23) & 0xff;
> > - const int flt_s = (fi.i >> 31) & 0x1;
> > - int s, e, m = 0;
> > - GLhalfARB result;
> > -
> > - /* sign bit */
> > - s = flt_s;
> > -
> > - /* handle special cases */
> > - if ((flt_e == 0) && (flt_m == 0)) {
> > - /* zero */
> > - /* m = 0; - already set */
> > - e = 0;
> > - }
> > - else if ((flt_e == 0) && (flt_m != 0)) {
> > - /* denorm -- denorm float maps to 0 half */
> > - /* m = 0; - already set */
> > - e = 0;
> > - }
> > - else if ((flt_e == 0xff) && (flt_m == 0)) {
> > - /* infinity */
> > - /* m = 0; - already set */
> > - e = 31;
> > - }
> > - else if ((flt_e == 0xff) && (flt_m != 0)) {
> > - /* NaN */
> > - m = 1;
> > - e = 31;
> > - }
> > - else {
> > - /* regular number */
> > - const int new_exp = flt_e - 127;
> > - if (new_exp < -14) {
> > - /* The float32 lies in the range (0.0, min_normal16) and is
rounded
> > - * to a nearby float16 value. The result will be either zero,
subnormal,
> > - * or normal.
> > - */
> > - e = 0;
> > - m = _mesa_lroundevenf((1 << 24) * fabsf(fi.f));
> > - }
> > - else if (new_exp > 15) {
> > - /* map this value to infinity */
> > - /* m = 0; - already set */
> > - e = 31;
> > - }
> > - else {
> > - /* The float32 lies in the range
> > - * [min_normal16, max_normal16 + max_step16)
> > - * and is rounded to a nearby float16 value. The result will
be
> > - * either normal or infinite.
> > - */
> > - e = new_exp + 15;
> > - m = _mesa_lroundevenf(flt_m / (float) (1 << 13));
> > - }
> > - }
> > -
> > - assert(0 <= m && m <= 1024);
> > - if (m == 1024) {
> > - /* The float32 was rounded upwards into the range of the next
exponent,
> > - * so bump the exponent. This correctly handles the case where
f32
> > - * should be rounded up to float16 infinity.
> > - */
> > - ++e;
> > - m = 0;
> > - }
> > -
> > - result = (s << 15) | (e << 10) | m;
> > - return result;
> > -}
> > -
> > -
> > -/**
> > - * Convert a 2-byte half float to a 4-byte float.
> > - * Based on code from:
> > - * http://www.opengl.org/discussion_boards/ubb/Forum3/HTML/008786.html
> > - */
> > -float
> > -_mesa_half_to_float(GLhalfARB val)
> > -{
> > - /* XXX could also use a 64K-entry lookup table */
> > - const int m = val & 0x3ff;
> > - const int e = (val >> 10) & 0x1f;
> > - const int s = (val >> 15) & 0x1;
> > - int flt_m, flt_e, flt_s;
> > - fi_type fi;
> > - float result;
> > -
> > - /* sign bit */
> > - flt_s = s;
> > -
> > - /* handle special cases */
> > - if ((e == 0) && (m == 0)) {
> > - /* zero */
> > - flt_m = 0;
> > - flt_e = 0;
> > - }
> > - else if ((e == 0) && (m != 0)) {
> > - /* denorm -- denorm half will fit in non-denorm single */
> > - const float half_denorm = 1.0f / 16384.0f; /* 2^-14 */
> > - float mantissa = ((float) (m)) / 1024.0f;
> > - float sign = s ? -1.0f : 1.0f;
> > - return sign * mantissa * half_denorm;
> > - }
> > - else if ((e == 31) && (m == 0)) {
> > - /* infinity */
> > - flt_e = 0xff;
> > - flt_m = 0;
> > - }
> > - else if ((e == 31) && (m != 0)) {
> > - /* NaN */
> > - flt_e = 0xff;
> > - flt_m = 1;
> > - }
> > - else {
> > - /* regular */
> > - flt_e = e + 112;
> > - flt_m = m << 13;
> > - }
> > -
> > - fi.i = (flt_s << 31) | (flt_e << 23) | flt_m;
> > - result = fi.f;
> > - return result;
> > -}
> > -
> > /*@}*/
> >
> >
> > diff --git a/src/mesa/main/imports.h b/src/mesa/main/imports.h
> > index 9024758..3a09304 100644
> > --- a/src/mesa/main/imports.h
> > +++ b/src/mesa/main/imports.h
> > @@ -42,6 +42,7 @@
> > #include "compiler.h"
> > #include "glheader.h"
> > #include "errors.h"
> > +#include "util/convert.h"
> >
> > #ifdef __cplusplus
> > extern "C" {
> > @@ -396,12 +397,41 @@ _mesa_flsll(uint64_t n)
> > #endif
> > }
> >
> > +/**
> > + * Convert a 4-byte float to a 2-byte half float.
> > + *
> > + * Not all float32 values can be represented exactly as a float16
value. We
> > + * round such intermediate float32 values to the nearest float16. When
the
> > + * float32 lies exactly between to float16 values, we round to the one
with
> > + * an even mantissa.
> > + *
> > + * This rounding behavior has several benefits:
> > + * - It has no sign bias.
> > + *
> > + * - It reproduces the behavior of real hardware: opcode F32TO16 in
Intel's
> > + * GPU ISA.
> > + *
> > + * - By reproducing the behavior of the GPU (at least on Intel
hardware),
> > + * compile-time evaluation of constant packHalf2x16 GLSL
expressions will
> > + * result in the same value as if the expression were executed on
the GPU.
> > + */
> > +static inline GLhalfARB
> > +_mesa_float_to_half(float val)
> > +{
> > + return float_to_half(val);
> > +}
> >
> > -extern GLhalfARB
> > -_mesa_float_to_half(float f);
> >
> > -extern float
> > -_mesa_half_to_float(GLhalfARB h);
> > +/**
> > + * Convert a 2-byte half float to a 4-byte float.
> > + * Based on code from:
> > + * http://www.opengl.org/discussion_boards/ubb/Forum3/HTML/008786.html
> > + */
> > +static inline float
> > +_mesa_half_to_float(GLhalfARB val)
> > +{
> > + return half_to_float(val);
> > +}
This is kind of ugly. How hard would it really be to just replace the uses
with the new name? I don't think its used *that* often.
> > static inline bool
> > _mesa_half_is_negative(GLhalfARB h)
> > diff --git a/src/util/Makefile.sources b/src/util/Makefile.sources
> > index e45431d..71b2a25 100644
> > --- a/src/util/Makefile.sources
> > +++ b/src/util/Makefile.sources
> > @@ -1,5 +1,7 @@
> > MESA_UTIL_FILES := \
> > bitset.h \
> > + convert.c \
> > + convert.h \
> > debug.c \
> > debug.h \
> > format_srgb.h \
> > diff --git a/src/util/convert.c b/src/util/convert.c
> > new file mode 100644
> > index 0000000..e86e322
> > --- /dev/null
> > +++ b/src/util/convert.c
>
> half-float.c seems like a better name.
Agreed.
> > @@ -0,0 +1,179 @@
> > +/*
> > + * Copyright © 2015 Red Hat
>
> What the?
>
> No. This code was written by Brian (commit 7eb3e9b) and Chad (commit
> 529b6d1). Its copyright belongs to VMware and Intel (and probably
> "gking" from [1])
>
> [1]
https://web.archive.org/web/20030303115125/http://www.opengl.org/discussion_boards/ubb/Forum3/HTML/008786.html
>
> > + *
> > + * Permission is hereby granted, free of charge, to any person
obtaining a
> > + * copy of this software and associated documentation files (the
"Software"),
> > + * to deal in the Software without restriction, including without
limitation
> > + * the rights to use, copy, modify, merge, publish, distribute,
sublicense,
> > + * and/or sell copies of the Software, and to permit persons to whom
the
> > + * Software is furnished to do so, subject to the following conditions:
> > + *
> > + * The above copyright notice and this permission notice (including
the next
> > + * paragraph) shall be included in all copies or substantial portions
of the
> > + * Software.
> > + *
> > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR
> > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY,
> > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
SHALL
> > + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES
OR OTHER
> > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING
> > + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS
> > + * IN THE SOFTWARE.
> > + *
> > + * Authors:
> > + * Rob Clark <robclark at freedesktop.org>
>
> We're trying to stop with author lists generally, but listing yourself
> as an author on some code you copied from somewhere else is not okay.
>
> > + */
> > +
> > +#include <math.h>
> > +#include <assert.h>
> > +#include "convert.h"
> > +#include "rounding.h"
> > +
> > +typedef union { float f; int32_t i; uint32_t u; } fi_type;
> > +
> > +/**
> > + * Convert a 4-byte float to a 2-byte half float.
> > + *
> > + * Not all float32 values can be represented exactly as a float16
value. We
> > + * round such intermediate float32 values to the nearest float16. When
the
> > + * float32 lies exactly between to float16 values, we round to the one
with
> > + * an even mantissa.
> > + *
> > + * This rounding behavior has several benefits:
> > + * - It has no sign bias.
> > + *
> > + * - It reproduces the behavior of real hardware: opcode F32TO16 in
Intel's
> > + * GPU ISA.
> > + *
> > + * - By reproducing the behavior of the GPU (at least on Intel
hardware),
> > + * compile-time evaluation of constant packHalf2x16 GLSL
expressions will
> > + * result in the same value as if the expression were executed on
the GPU.
> > + */
> > +uint16_t
> > +float_to_half(float val)
> > +{
> > + const fi_type fi = {val};
> > + const int flt_m = fi.i & 0x7fffff;
> > + const int flt_e = (fi.i >> 23) & 0xff;
> > + const int flt_s = (fi.i >> 31) & 0x1;
> > + int s, e, m = 0;
> > + uint16_t result;
> > +
> > + /* sign bit */
> > + s = flt_s;
> > +
> > + /* handle special cases */
> > + if ((flt_e == 0) && (flt_m == 0)) {
> > + /* zero */
> > + /* m = 0; - already set */
> > + e = 0;
> > + }
> > + else if ((flt_e == 0) && (flt_m != 0)) {
> > + /* denorm -- denorm float maps to 0 half */
> > + /* m = 0; - already set */
> > + e = 0;
> > + }
> > + else if ((flt_e == 0xff) && (flt_m == 0)) {
> > + /* infinity */
> > + /* m = 0; - already set */
> > + e = 31;
> > + }
> > + else if ((flt_e == 0xff) && (flt_m != 0)) {
> > + /* NaN */
> > + m = 1;
> > + e = 31;
> > + }
> > + else {
> > + /* regular number */
> > + const int new_exp = flt_e - 127;
> > + if (new_exp < -14) {
> > + /* The float32 lies in the range (0.0, min_normal16) and is
rounded
> > + * to a nearby float16 value. The result will be either zero,
subnormal,
> > + * or normal.
> > + */
> > + e = 0;
> > + m = _mesa_lroundevenf((1 << 24) * fabsf(fi.f));
> > + }
> > + else if (new_exp > 15) {
> > + /* map this value to infinity */
> > + /* m = 0; - already set */
> > + e = 31;
> > + }
> > + else {
> > + /* The float32 lies in the range
> > + * [min_normal16, max_normal16 + max_step16)
> > + * and is rounded to a nearby float16 value. The result will
be
> > + * either normal or infinite.
> > + */
> > + e = new_exp + 15;
> > + m = _mesa_lroundevenf(flt_m / (float) (1 << 13));
> > + }
> > + }
> > +
> > + assert(0 <= m && m <= 1024);
> > + if (m == 1024) {
> > + /* The float32 was rounded upwards into the range of the next
exponent,
> > + * so bump the exponent. This correctly handles the case where
f32
> > + * should be rounded up to float16 infinity.
> > + */
> > + ++e;
> > + m = 0;
> > + }
> > +
> > + result = (s << 15) | (e << 10) | m;
> > + return result;
> > +}
> > +
> > +
> > +/**
> > + * Convert a 2-byte half float to a 4-byte float.
> > + * Based on code from:
> > + * http://www.opengl.org/discussion_boards/ubb/Forum3/HTML/008786.html
> > + */
> > +float
> > +half_to_float(uint16_t val)
> > +{
> > + /* XXX could also use a 64K-entry lookup table */
> > + const int m = val & 0x3ff;
> > + const int e = (val >> 10) & 0x1f;
> > + const int s = (val >> 15) & 0x1;
> > + int flt_m, flt_e, flt_s;
> > + fi_type fi;
> > + float result;
> > +
> > + /* sign bit */
> > + flt_s = s;
> > +
> > + /* handle special cases */
> > + if ((e == 0) && (m == 0)) {
> > + /* zero */
> > + flt_m = 0;
> > + flt_e = 0;
> > + }
> > + else if ((e == 0) && (m != 0)) {
> > + /* denorm -- denorm half will fit in non-denorm single */
> > + const float half_denorm = 1.0f / 16384.0f; /* 2^-14 */
> > + float mantissa = ((float) (m)) / 1024.0f;
> > + float sign = s ? -1.0f : 1.0f;
> > + return sign * mantissa * half_denorm;
> > + }
> > + else if ((e == 31) && (m == 0)) {
> > + /* infinity */
> > + flt_e = 0xff;
> > + flt_m = 0;
> > + }
> > + else if ((e == 31) && (m != 0)) {
> > + /* NaN */
> > + flt_e = 0xff;
> > + flt_m = 1;
> > + }
> > + else {
> > + /* regular */
> > + flt_e = e + 112;
> > + flt_m = m << 13;
> > + }
> > +
> > + fi.i = (flt_s << 31) | (flt_e << 23) | flt_m;
> > + result = fi.f;
> > + return result;
> > +}
> > diff --git a/src/util/convert.h b/src/util/convert.h
> > new file mode 100644
> > index 0000000..30d36a1
> > --- /dev/null
> > +++ b/src/util/convert.h
> > @@ -0,0 +1,43 @@
> > +/*
> > + * Copyright © 2015 Red Hat
>
> Seems fishy.
>
> > + *
> > + * Permission is hereby granted, free of charge, to any person
obtaining a
> > + * copy of this software and associated documentation files (the
"Software"),
> > + * to deal in the Software without restriction, including without
limitation
> > + * the rights to use, copy, modify, merge, publish, distribute,
sublicense,
> > + * and/or sell copies of the Software, and to permit persons to whom
the
> > + * Software is furnished to do so, subject to the following conditions:
> > + *
> > + * The above copyright notice and this permission notice (including
the next
> > + * paragraph) shall be included in all copies or substantial portions
of the
> > + * Software.
> > + *
> > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR
> > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY,
> > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
SHALL
> > + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES
OR OTHER
> > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING
> > + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS
> > + * IN THE SOFTWARE.
> > + *
> > + * Authors:
> > + * Rob Clark <robclark at freedesktop.org>
>
> Again, no author list.
>
> > + */
> > +
> > +#ifndef _MATH_H_
> > +#define _MATH_H_
>
> Wrong name.
>
> > +
> > +#include <stdint.h>
> > +
> > +#ifdef __cplusplus
> > +extern "C" {
> > +#endif
> > +
> > +uint16_t float_to_half(float val);
> > +float half_to_float(uint16_t val);
>
> I think these functions need to be prefixed with something -- util_*
> or something or just leave them as _mesa_*.
Unfortunately, until is kind of a grab-bag right now. Some stuff has a
util_ prefix, some has kept its _mesa_ or u_ prefix depending on whether it
was copied from Mesa or gallium, and some (hash_table for example) isn't
prefixed at all. Personally, I'd go with either util_ (it is a utility
library) or just keep _mesa_ (this is still the mesa project after all).
I'm not going to be too insistent though
> > +
> > +#ifdef __cplusplus
> > +} /* extern C */
> > +#endif
> > +
> > +#endif /* _MATH_H_ */
> _______________________________________________
> mesa-dev mailing list
> mesa-dev at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
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