src/gallium/auxiliary/util/u_format_srgb.h

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/**
 * @file
 * SRGB translation.
 *
 * @author Brian Paul <brianp@vmware.com>
 * @author Michal Krol <michal@vmware.com>
 * @author Jose Fonseca <jfonseca@vmware.com>
 */

#ifndef U_FORMAT_SRGB_H_
#define U_FORMAT_SRGB_H_


#include "pipe/p_compiler.h"
#include "u_math.h"


extern const float
util_format_srgb_8unorm_to_linear_float_table[256];

extern const uint8_t
util_format_srgb_to_linear_8unorm_table[256];

extern const uint8_t
util_format_linear_to_srgb_8unorm_table[256];


/**
 * Convert a unclamped linear float to srgb value in the [0,255].
 * XXX this hasn't been tested (render to srgb surface).
 * XXX this needs optimization.
 */
static INLINE uint8_t
util_format_linear_float_to_srgb_8unorm(float x)
{
   if (x >= 1.0f)
      return 255;
   else if (x >= 0.0031308f)
      return float_to_ubyte(1.055f * powf(x, 0.41666f) - 0.055f);
   else if (x > 0.0f)
      return float_to_ubyte(12.92f * x);
   else
      return 0;
}


/**
 * Convert an 8-bit sRGB value from non-linear space to a
 * linear RGB value in [0, 1].
 * Implemented with a 256-entry lookup table.
 */
static INLINE float
util_format_srgb_8unorm_to_linear_float(uint8_t x)
{
   return util_format_srgb_8unorm_to_linear_float_table[x];
}


/**
 * Convert a 8bit normalized value from linear to srgb.
 */
static INLINE uint8_t
util_format_linear_to_srgb_8unorm(uint8_t x)
{
   return util_format_linear_to_srgb_8unorm_table[x];
}


/**
 * Convert a 8bit normalized value from srgb to linear.
 */
static INLINE uint8_t
util_format_srgb_to_linear_8unorm(uint8_t x)
{
   return util_format_srgb_to_linear_8unorm_table[x];
}


#endif /* U_FORMAT_SRGB_H_ */