static void restore_median(uint8_t *src, int step, int stride, int width, int height, int slices, int rmode) { int i, j, slice; int A, B, C; uint8_t *bsrc; int slice_start, slice_height; const int cmask = ~rmode; for (slice = 0; slice < slices; slice++) { slice_start = ((slice * height) / slices) & cmask; slice_height = ((((slice + 1) * height) / slices) & cmask) - slice_start; bsrc = src + slice_start * stride; // first line - left neighbour prediction bsrc[0] += 0x80; A = bsrc[0]; for (i = step; i < width * step; i += step) { bsrc[i] += A; A = bsrc[i]; } bsrc += stride; if (slice_height == 1) // second line - first element has top prediction, the rest uses median C = bsrc[-stride]; bsrc[0] += C; A = bsrc[0]; for (i = step; i < width * step; i += step) { B = bsrc[i - stride]; bsrc[i] += mid_pred(A, B, (uint8_t)(A + B - C)); C = B; A = bsrc[i]; } bsrc += stride; // the rest of lines use continuous median prediction for (j = 2; j < slice_height; j++) { for (i = 0; i < width * step; i += step) { B = bsrc[i - stride]; bsrc[i] += mid_pred(A, B, (uint8_t)(A + B - C)); C = B; A = bsrc[i]; } bsrc += stride; } } }