colors.h

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#ifndef COLORS_H
#define COLORS_H
 
#include <smmintrin.h>
 
#include <stdint.h>
 
/*****************************************************************************/
inline uint32_t colorsScaleSSE4(uint32_t color, uint16_t scale)
{
// Load color and unpack bytes to words
    __m128i c = _mm_cvtsi32_si128((int) color);
    __m128i c_unpacked = _mm_cvtepu8_epi32(c);
 
// Multiply color by scale
    __m128i scale32 = _mm_set1_epi32(scale);
    __m128i result = _mm_mullo_epi32(c_unpacked, scale32);
    result = _mm_srli_epi32(result, 16);
 
// Pack back to bytes
    result = _mm_packus_epi32(result, result);
    result = _mm_packus_epi16(result, result);
 
    return _mm_cvtsi128_si32(result);
}

inline uint32_t colorsMultiplySSE4(uint32_t color1, uint32_t color2)
{
// Load colors and unpack bytes to words
    __m128i c1 = _mm_cvtsi32_si128((int) color1);
    __m128i c2 = _mm_cvtsi32_si128((int) color2);
    __m128i c1_unpacked = _mm_cvtepu8_epi32(c1);
    __m128i c2_unpacked = _mm_cvtepu8_epi32(c2);
 
// Multiply the components
    __m128i result = _mm_mullo_epi32(c1_unpacked, c2_unpacked);
    result = _mm_srli_epi32(result, 8);
 
// Pack back to bytes
    result = _mm_packus_epi32(result, result);
    result = _mm_packus_epi16(result, result);
    return _mm_cvtsi128_si32(result);
}

inline uint32_t colorsLinearSSE4(uint32_t color1, uint32_t color2, uint16_t t)
{
// Load colors and unpack bytes to words
    __m128i c1 = _mm_cvtsi32_si128((int) color1);
    __m128i c2 = _mm_cvtsi32_si128((int) color2);
    __m128i c1_unpacked = _mm_cvtepu8_epi32(c1);
    __m128i c2_unpacked = _mm_cvtepu8_epi32(c2);
 
// Calculate difference (color2 - color1)
    __m128i diff = _mm_sub_epi32(c2_unpacked, c1_unpacked);
 
// Compute linear interpolation color1 + (color2 - color1) * t
    __m128i scaled_diff = _mm_mullo_epi32(diff, _mm_set1_epi32(t));
    __m128i result = _mm_add_epi32(c1_unpacked, _mm_srai_epi32(scaled_diff, 8));
 
// Pack back to bytes
    result = _mm_packus_epi32(result, result);
    result = _mm_packus_epi16(result, result);
    return _mm_cvtsi128_si32(result);
}

inline uint32_t colorsScaleAccumulateSSE4(uint32_t color1, uint32_t color2, uint16_t scale)
{
// Load colors and unpack bytes to words
    __m128i c1 = _mm_cvtsi32_si128((int) color1);
    __m128i c2 = _mm_cvtsi32_si128((int) color2);
    __m128i c1_unpacked = _mm_cvtepu8_epi32(c1);
    __m128i c2_unpacked = _mm_cvtepu8_epi32(c2);
 
// Compute scaling color2 * t
    __m128i scaled_c2 = _mm_mullo_epi32(c2_unpacked, _mm_set1_epi32(scale));
    scaled_c2 = _mm_srli_epi32(scaled_c2, 8);
 
// Add to accumulator (packus saturates to 255)
    __m128i result = _mm_add_epi32(c1_unpacked, scaled_c2);
 
// Pack back to bytes
    result = _mm_packus_epi32(result, result);
    result = _mm_packus_epi16(result, result);
    return _mm_cvtsi128_si32(result);
}
 
/*****************************************************************************/
inline __m128 vectorLinearSSE4(__m128 color1, __m128 color2, float t)
{
    __m128 delta = _mm_sub_ps(color2, color1);
    return _mm_add_ps(color1, _mm_mul_ps(delta, _mm_set1_ps(t)));
}
 
/*****************************************************************************/
inline __m128 unpackColorToVectorSSE4(uint32_t color)
{
    static constexpr float d8 = 1.0f / 256.0f;
    __m128i vec4i = _mm_cvtsi32_si128((int) color);
    vec4i = _mm_cvtepu8_epi32(vec4i);
    __m128  vec4f = _mm_cvtepi32_ps(vec4i);
    return _mm_mul_ps(vec4f, _mm_set1_ps(d8));
}

inline __m128 unpackColorToVectorScaledSSE4(uint32_t color, float scale)
{
    static constexpr float d8 = 1.0f / 256.0f;
    __m128i vec4i = _mm_cvtsi32_si128((int) color);
    vec4i = _mm_cvtepu8_epi32(vec4i);
    __m128  vec4f = _mm_cvtepi32_ps(vec4i);
    return _mm_mul_ps(vec4f, _mm_set1_ps(scale * d8));
}

inline uint32_t packVectorToColorSSE4(__m128 color)
{
    color = _mm_mul_ps(color, _mm_set1_ps(256.0f));
    __m128i vec4i = _mm_cvttps_epi32(color);
    vec4i = _mm_packus_epi32(vec4i, vec4i);
    vec4i = _mm_packus_epi16(vec4i, vec4i);
    return _mm_cvtsi128_si32(vec4i);
}
 
#endif // COLORS_H