fdo-mirrors/mesa
1
0
Fork 0
mirror of https://gitlab.freedesktop.org/mesa/mesa.git synced 2026-05-09 04:38:03 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions 1

util/rgb9e5: Get rid of the float754 union

Browse source 
There are a number of reasons for this refactor.  First, format_rgb9e5.h is
not something that a user would expect to define such a generic union.
Second, defining it requires checking for endianness which is ugly.  Third,
90% of what we were doing with the union was float <-> uint32_t bitcasts
and the remaining 10% can be done with a sinmple left-shift by 23.

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
This commit is contained in:
Jason Ekstrand 2016-08-03 09:54:03 -07:00
parent cda8d95660
commit c7eb9a7565
1 changed files with 27 additions and 42 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

69
src/util/format_rgb9e5.h
View file

@ -28,6 +28,7 @@
#define RGB9E5_H
#include <assert.h>
#include <stdint.h>
#include "c99_math.h"
@ -41,59 +42,43 @@
#define MAX_RGB9E5_MANTISSA (RGB9E5_MANTISSA_VALUES-1)
#define MAX_RGB9E5 (((float)MAX_RGB9E5_MANTISSA)/RGB9E5_MANTISSA_VALUES * (1<<MAX_RGB9E5_EXP))
typedef union {
unsigned int raw;
float value;
struct {
#if defined(MESA_BIG_ENDIAN) || defined(PIPE_ARCH_BIG_ENDIAN)
unsigned int negative:1;
unsigned int biasedexponent:8;
unsigned int mantissa:23;
#else
unsigned int mantissa:23;
unsigned int biasedexponent:8;
unsigned int negative:1;
#endif
} field;
} float754;
static inline int rgb9e5_ClampRange(float x)
{
float754 f;
float754 max;
f.value = x;
max.value = MAX_RGB9E5;
union { float f; uint32_t u; } f, max;
f.f = x;
max.f = MAX_RGB9E5;
if (f.raw > 0x7f800000)
if (f.u > 0x7f800000)
/* catches neg, NaNs */
return 0;
else if (f.raw >= max.raw)
return max.raw;
else if (f.u >= max.u)
return max.u;
else
return f.raw;
return f.u;
}
static inline unsigned int float3_to_rgb9e5(const float rgb[3])
{
int rm, gm, bm, exp_shared;
float754 revdenom = {0};
float754 rc, bc, gc, maxrgb;
uint32_t revdenom_biasedexp;
union { float f; uint32_t u; } rc, bc, gc, maxrgb, revdenom;
rc.raw = rgb9e5_ClampRange(rgb[0]);
gc.raw = rgb9e5_ClampRange(rgb[1]);
bc.raw = rgb9e5_ClampRange(rgb[2]);
maxrgb.raw = MAX3(rc.raw, gc.raw, bc.raw);
rc.u = rgb9e5_ClampRange(rgb[0]);
gc.u = rgb9e5_ClampRange(rgb[1]);
bc.u = rgb9e5_ClampRange(rgb[2]);
maxrgb.u = MAX3(rc.u, gc.u, bc.u);
/*
* Compared to what the spec suggests, instead of conditionally adjusting
* the exponent after the fact do it here by doing the equivalent of +0.5 -
* the int add will spill over into the exponent in this case.
*/
maxrgb.raw += maxrgb.raw & (1 << (23-9));
exp_shared = MAX2((maxrgb.raw >> 23), -RGB9E5_EXP_BIAS - 1 + 127) +
maxrgb.u += maxrgb.u & (1 << (23-9));
exp_shared = MAX2((maxrgb.u >> 23), -RGB9E5_EXP_BIAS - 1 + 127) +
1 + RGB9E5_EXP_BIAS - 127;
revdenom.field.biasedexponent = 127 - (exp_shared - RGB9E5_EXP_BIAS -
RGB9E5_MANTISSA_BITS) + 1;
revdenom_biasedexp = 127 - (exp_shared - RGB9E5_EXP_BIAS -
RGB9E5_MANTISSA_BITS) + 1;
revdenom.u = revdenom_biasedexp << 23;
assert(exp_shared <= RGB9E5_MAX_VALID_BIASED_EXP);
/*
@ -102,9 +87,9 @@ static inline unsigned int float3_to_rgb9e5(const float rgb[3])
* We avoid the doubles ((int) rc * revdenom + 0.5) by doing the rounding
* ourselves (revdenom was adjusted by +1, above).
*/
rm = (int) (rc.value * revdenom.value);
gm = (int) (gc.value * revdenom.value);
bm = (int) (bc.value * revdenom.value);
rm = (int) (rc.f * revdenom.f);
gm = (int) (gc.f * revdenom.f);
bm = (int) (bc.f * revdenom.f);
rm = (rm & 1) + (rm >> 1);
gm = (gm & 1) + (gm >> 1);
bm = (bm & 1) + (bm >> 1);
@ -122,14 +107,14 @@ static inline unsigned int float3_to_rgb9e5(const float rgb[3])
static inline void rgb9e5_to_float3(unsigned rgb, float retval[3])
{
int exponent;
float754 scale = {0};
union { float f; uint32_t u; } scale;
exponent = (rgb >> 27) - RGB9E5_EXP_BIAS - RGB9E5_MANTISSA_BITS;
scale.field.biasedexponent = exponent + 127;
scale.u = (exponent + 127) << 23;
retval[0] = ( rgb & 0x1ff) * scale.value;
retval[1] = ((rgb >> 9) & 0x1ff) * scale.value;
retval[2] = ((rgb >> 18) & 0x1ff) * scale.value;
retval[0] = ( rgb & 0x1ff) * scale.f;
retval[1] = ((rgb >> 9) & 0x1ff) * scale.f;
retval[2] = ((rgb >> 18) & 0x1ff) * scale.f;
}
#endif