dispatch.c File Reference

Go to the source code of this file.

Functions
const simd_backend_t *	simd_select_backend (uint32_t features)
const simd_backend_t *	simd_backend (void)
void	simd_luminance_scalar (const uint8_t *rgb, uint8_t *out, size_t count)

Function Documentation

simd_backend()

const simd_backend_t * simd_backend

(

void

)

Immutable dispatch table cached per thread; no startup constructors required.

Definition at line 36 of file dispatch.c.

                                         {
  static _Thread_local const simd_backend_t *selected;
  if (!selected) {
    uint32_t features = platform_cpu_features();
    selected = simd_select_backend(features);
    const char *requested = simd_backend_override();
    if (requested && requested[0] && strcmp(requested, "auto") != 0) {
      // A diagnostic override can never bypass the CPU/OS safety check.
      selected = simd_select_backend(0);
      for (size_t i = 0; i < sizeof(backends) / sizeof(backends[0]); i++) {
        if (strcmp(requested, backends[i].name) == 0 &&
            (features & backends[i].required_features) == backends[i].required_features) {
          selected = &backends[i];
          break;
        }
      }
    }
  }
  return selected;
}

References simd_select_backend().

Referenced by main(), and simd_cells_backend().

simd_luminance_scalar()

void simd_luminance_scalar	(	const uint8_t *	rgb,
		uint8_t *	out,
		size_t	count )

Definition at line 57 of file dispatch.c.

                                                                           {
  for (size_t i = 0; i < count; i++)
    out[i] = (uint8_t)((77u * rgb[3 * i] + 150u * rgb[3 * i + 1] + 29u * rgb[3 * i + 2] + 128u) >> 8);
}

References out.

Referenced by simd_luminance_avx2(), simd_luminance_neon(), simd_luminance_sse2(), and simd_luminance_ssse3().

simd_select_backend()

const simd_backend_t * simd_select_backend

(

uint32_t

features

)

Select only from compiled implementations whose requirements are satisfied.

Definition at line 28 of file dispatch.c.

                                                             {
  for (size_t i = 0; i < sizeof(backends) / sizeof(backends[0]); i++) {
    if ((features & backends[i].required_features) == backends[i].required_features)
      return &backends[i];
  }
  return &backends[sizeof(backends) / sizeof(backends[0]) - 1];
}

Referenced by simd_backend().