void meanStdDev(const Size2D &size,
const u8 * srcBase, ptrdiff_t srcStride,
f32 * pMean, f32 * pStdDev)
{
internal::assertSupportedConfiguration();
#ifdef CAROTENE_NEON
f64 fsum = 0.0f, fsqsum = 0.0f;
sqsum(size, srcBase, srcStride, &fsum, &fsqsum, 1);
// calc mean and stddev
f64 itotal = 1.0 / size.total();
f64 mean = fsum * itotal;
f64 stddev = sqrt(std::max(fsqsum * itotal - mean * mean, 0.0));
if (pMean)
*pMean = mean;
if (pStdDev)
*pStdDev = stddev;
#else
(void)size;
(void)srcBase;
(void)srcStride;
(void)pMean;
(void)pStdDev;
#endif
}
void meanStdDev(const Size2D &size,
const u16 * srcBase, ptrdiff_t srcStride,
f32 * pMean, f32 * pStdDev)
{
internal::assertSupportedConfiguration();
#ifdef CAROTENE_NEON
size_t blockSize0 = 1 << 10, roiw4 = size.width & ~3;
f64 fsum = 0.0f, fsqsum = 0.0f;
f32 arsum[8];
uint32x4_t v_zero = vdupq_n_u32(0u), v_sum;
float32x4_t v_zero_f = vdupq_n_f32(0.0f), v_sqsum;
for (size_t i = 0; i < size.height; ++i)
{
const u16 * src = internal::getRowPtr(srcBase, srcStride, i);
size_t j = 0u;
while (j < roiw4)
{
size_t blockSize = std::min(roiw4 - j, blockSize0) + j;
v_sum = v_zero;
v_sqsum = v_zero_f;
for ( ; j + 16 < blockSize ; j += 16)
{
internal::prefetch(src + j);
uint16x8_t v_src0 = vld1q_u16(src + j), v_src1 = vld1q_u16(src + j + 8);
// 0
uint32x4_t v_srclo = vmovl_u16(vget_low_u16(v_src0));
uint32x4_t v_srchi = vmovl_u16(vget_high_u16(v_src0));
v_sum = vaddq_u32(v_sum, vaddq_u32(v_srclo, v_srchi));
float32x4_t v_srclo_f = vcvtq_f32_u32(v_srclo);
float32x4_t v_srchi_f = vcvtq_f32_u32(v_srchi);
v_sqsum = vmlaq_f32(v_sqsum, v_srclo_f, v_srclo_f);
v_sqsum = vmlaq_f32(v_sqsum, v_srchi_f, v_srchi_f);
// 1
v_srclo = vmovl_u16(vget_low_u16(v_src1));
v_srchi = vmovl_u16(vget_high_u16(v_src1));
v_sum = vaddq_u32(v_sum, vaddq_u32(v_srclo, v_srchi));
v_srclo_f = vcvtq_f32_u32(v_srclo);
v_srchi_f = vcvtq_f32_u32(v_srchi);
v_sqsum = vmlaq_f32(v_sqsum, v_srclo_f, v_srclo_f);
v_sqsum = vmlaq_f32(v_sqsum, v_srchi_f, v_srchi_f);
}
for ( ; j < blockSize; j += 4)
{
uint32x4_t v_src = vmovl_u16(vld1_u16(src + j));
float32x4_t v_src_f = vcvtq_f32_u32(v_src);
v_sum = vaddq_u32(v_sum, v_src);
v_sqsum = vmlaq_f32(v_sqsum, v_src_f, v_src_f);
}
vst1q_f32(arsum, vcvtq_f32_u32(v_sum));
vst1q_f32(arsum + 4, v_sqsum);
fsum += (f64)arsum[0] + arsum[1] + arsum[2] + arsum[3];
fsqsum += (f64)arsum[4] + arsum[5] + arsum[6] + arsum[7];
}
// collect a few last elements in the current row
for ( ; j < size.width; ++j)
{
f32 srcval = src[j];
fsum += srcval;
fsqsum += srcval * srcval;
}
}
// calc mean and stddev
f64 itotal = 1.0 / size.total();
f64 mean = fsum * itotal;
f64 stddev = sqrt(std::max(fsqsum * itotal - mean * mean, 0.0));
if (pMean)
*pMean = mean;
if (pStdDev)
*pStdDev = stddev;
#else
(void)size;
(void)srcBase;
(void)srcStride;
(void)pMean;
(void)pStdDev;
#endif
}
