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-rw-r--r--third_party/aom/aom_dsp/avg.c573
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diff --git a/third_party/aom/aom_dsp/avg.c b/third_party/aom/aom_dsp/avg.c
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index 0000000000..893f9c2f65
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+++ b/third_party/aom/aom_dsp/avg.c
@@ -0,0 +1,573 @@
+/*
+ * Copyright (c) 2016, Alliance for Open Media. All rights reserved
+ *
+ * This source code is subject to the terms of the BSD 2 Clause License and
+ * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
+ * was not distributed with this source code in the LICENSE file, you can
+ * obtain it at www.aomedia.org/license/software. If the Alliance for Open
+ * Media Patent License 1.0 was not distributed with this source code in the
+ * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
+ */
+
+#include <assert.h>
+#include <stdlib.h>
+
+#include "config/aom_dsp_rtcd.h"
+#include "aom_ports/mem.h"
+
+void aom_minmax_8x8_c(const uint8_t *s, int p, const uint8_t *d, int dp,
+ int *min, int *max) {
+ int i, j;
+ *min = 255;
+ *max = 0;
+ for (i = 0; i < 8; ++i, s += p, d += dp) {
+ for (j = 0; j < 8; ++j) {
+ int diff = abs(s[j] - d[j]);
+ *min = diff < *min ? diff : *min;
+ *max = diff > *max ? diff : *max;
+ }
+ }
+}
+
+unsigned int aom_avg_4x4_c(const uint8_t *s, int p) {
+ int i, j;
+ int sum = 0;
+ for (i = 0; i < 4; ++i, s += p)
+ for (j = 0; j < 4; sum += s[j], ++j) {
+ }
+
+ return (sum + 8) >> 4;
+}
+
+unsigned int aom_avg_8x8_c(const uint8_t *s, int p) {
+ int i, j;
+ int sum = 0;
+ for (i = 0; i < 8; ++i, s += p)
+ for (j = 0; j < 8; sum += s[j], ++j) {
+ }
+
+ return (sum + 32) >> 6;
+}
+
+void aom_avg_8x8_quad_c(const uint8_t *s, int p, int x16_idx, int y16_idx,
+ int *avg) {
+ for (int k = 0; k < 4; k++) {
+ const int x8_idx = x16_idx + ((k & 1) << 3);
+ const int y8_idx = y16_idx + ((k >> 1) << 3);
+ const uint8_t *s_tmp = s + y8_idx * p + x8_idx;
+ avg[k] = aom_avg_8x8_c(s_tmp, p);
+ }
+}
+
+#if CONFIG_AV1_HIGHBITDEPTH
+unsigned int aom_highbd_avg_8x8_c(const uint8_t *s8, int p) {
+ int i, j;
+ int sum = 0;
+ const uint16_t *s = CONVERT_TO_SHORTPTR(s8);
+ for (i = 0; i < 8; ++i, s += p)
+ for (j = 0; j < 8; sum += s[j], ++j) {
+ }
+
+ return (sum + 32) >> 6;
+}
+
+unsigned int aom_highbd_avg_4x4_c(const uint8_t *s8, int p) {
+ int i, j;
+ int sum = 0;
+ const uint16_t *s = CONVERT_TO_SHORTPTR(s8);
+ for (i = 0; i < 4; ++i, s += p)
+ for (j = 0; j < 4; sum += s[j], ++j) {
+ }
+
+ return (sum + 8) >> 4;
+}
+
+void aom_highbd_minmax_8x8_c(const uint8_t *s8, int p, const uint8_t *d8,
+ int dp, int *min, int *max) {
+ int i, j;
+ const uint16_t *s = CONVERT_TO_SHORTPTR(s8);
+ const uint16_t *d = CONVERT_TO_SHORTPTR(d8);
+ *min = 65535;
+ *max = 0;
+ for (i = 0; i < 8; ++i, s += p, d += dp) {
+ for (j = 0; j < 8; ++j) {
+ int diff = abs(s[j] - d[j]);
+ *min = diff < *min ? diff : *min;
+ *max = diff > *max ? diff : *max;
+ }
+ }
+}
+#endif // CONFIG_AV1_HIGHBITDEPTH
+
+static void hadamard_col4(const int16_t *src_diff, ptrdiff_t src_stride,
+ int16_t *coeff) {
+ int16_t b0 = (src_diff[0 * src_stride] + src_diff[1 * src_stride]) >> 1;
+ int16_t b1 = (src_diff[0 * src_stride] - src_diff[1 * src_stride]) >> 1;
+ int16_t b2 = (src_diff[2 * src_stride] + src_diff[3 * src_stride]) >> 1;
+ int16_t b3 = (src_diff[2 * src_stride] - src_diff[3 * src_stride]) >> 1;
+
+ coeff[0] = b0 + b2;
+ coeff[1] = b1 + b3;
+ coeff[2] = b0 - b2;
+ coeff[3] = b1 - b3;
+}
+
+void aom_hadamard_4x4_c(const int16_t *src_diff, ptrdiff_t src_stride,
+ tran_low_t *coeff) {
+ int idx;
+ int16_t buffer[16];
+ int16_t buffer2[16];
+ int16_t *tmp_buf = &buffer[0];
+ for (idx = 0; idx < 4; ++idx) {
+ hadamard_col4(src_diff, src_stride, tmp_buf); // src_diff: 9 bit
+ // dynamic range [-255, 255]
+ tmp_buf += 4;
+ ++src_diff;
+ }
+
+ tmp_buf = &buffer[0];
+ for (idx = 0; idx < 4; ++idx) {
+ hadamard_col4(tmp_buf, 4, buffer2 + 4 * idx); // tmp_buf: 12 bit
+ // dynamic range [-2040, 2040]
+ // buffer2: 15 bit
+ // dynamic range [-16320, 16320]
+ ++tmp_buf;
+ }
+
+ // Extra transpose to match SSE2 behavior(i.e., aom_hadamard_4x4_sse2).
+ for (int i = 0; i < 4; i++) {
+ for (int j = 0; j < 4; j++) {
+ coeff[i * 4 + j] = (tran_low_t)buffer2[j * 4 + i];
+ }
+ }
+}
+
+// src_diff: first pass, 9 bit, dynamic range [-255, 255]
+// second pass, 12 bit, dynamic range [-2040, 2040]
+static void hadamard_col8(const int16_t *src_diff, ptrdiff_t src_stride,
+ int16_t *coeff) {
+ int16_t b0 = src_diff[0 * src_stride] + src_diff[1 * src_stride];
+ int16_t b1 = src_diff[0 * src_stride] - src_diff[1 * src_stride];
+ int16_t b2 = src_diff[2 * src_stride] + src_diff[3 * src_stride];
+ int16_t b3 = src_diff[2 * src_stride] - src_diff[3 * src_stride];
+ int16_t b4 = src_diff[4 * src_stride] + src_diff[5 * src_stride];
+ int16_t b5 = src_diff[4 * src_stride] - src_diff[5 * src_stride];
+ int16_t b6 = src_diff[6 * src_stride] + src_diff[7 * src_stride];
+ int16_t b7 = src_diff[6 * src_stride] - src_diff[7 * src_stride];
+
+ int16_t c0 = b0 + b2;
+ int16_t c1 = b1 + b3;
+ int16_t c2 = b0 - b2;
+ int16_t c3 = b1 - b3;
+ int16_t c4 = b4 + b6;
+ int16_t c5 = b5 + b7;
+ int16_t c6 = b4 - b6;
+ int16_t c7 = b5 - b7;
+
+ coeff[0] = c0 + c4;
+ coeff[7] = c1 + c5;
+ coeff[3] = c2 + c6;
+ coeff[4] = c3 + c7;
+ coeff[2] = c0 - c4;
+ coeff[6] = c1 - c5;
+ coeff[1] = c2 - c6;
+ coeff[5] = c3 - c7;
+}
+
+void aom_hadamard_8x8_c(const int16_t *src_diff, ptrdiff_t src_stride,
+ tran_low_t *coeff) {
+ int idx;
+ int16_t buffer[64];
+ int16_t buffer2[64];
+ int16_t *tmp_buf = &buffer[0];
+ for (idx = 0; idx < 8; ++idx) {
+ hadamard_col8(src_diff, src_stride, tmp_buf); // src_diff: 9 bit
+ // dynamic range [-255, 255]
+ tmp_buf += 8;
+ ++src_diff;
+ }
+
+ tmp_buf = &buffer[0];
+ for (idx = 0; idx < 8; ++idx) {
+ hadamard_col8(tmp_buf, 8, buffer2 + 8 * idx); // tmp_buf: 12 bit
+ // dynamic range [-2040, 2040]
+ // buffer2: 15 bit
+ // dynamic range [-16320, 16320]
+ ++tmp_buf;
+ }
+
+ // Extra transpose to match SSE2 behavior(i.e., aom_hadamard_8x8_sse2).
+ for (int i = 0; i < 8; i++) {
+ for (int j = 0; j < 8; j++) {
+ coeff[i * 8 + j] = (tran_low_t)buffer2[j * 8 + i];
+ }
+ }
+}
+
+void aom_hadamard_lp_8x8_c(const int16_t *src_diff, ptrdiff_t src_stride,
+ int16_t *coeff) {
+ int16_t buffer[64];
+ int16_t buffer2[64];
+ int16_t *tmp_buf = &buffer[0];
+ for (int idx = 0; idx < 8; ++idx) {
+ hadamard_col8(src_diff, src_stride, tmp_buf); // src_diff: 9 bit
+ // dynamic range [-255, 255]
+ tmp_buf += 8;
+ ++src_diff;
+ }
+
+ tmp_buf = &buffer[0];
+ for (int idx = 0; idx < 8; ++idx) {
+ hadamard_col8(tmp_buf, 8, buffer2 + 8 * idx); // tmp_buf: 12 bit
+ // dynamic range [-2040, 2040]
+ // buffer2: 15 bit
+ // dynamic range [-16320, 16320]
+ ++tmp_buf;
+ }
+
+ for (int idx = 0; idx < 64; ++idx) coeff[idx] = buffer2[idx];
+
+ // Extra transpose to match SSE2 behavior(i.e., aom_hadamard_lp_8x8_sse2).
+ for (int i = 0; i < 8; i++) {
+ for (int j = 0; j < 8; j++) {
+ coeff[i * 8 + j] = buffer2[j * 8 + i];
+ }
+ }
+}
+
+void aom_hadamard_lp_8x8_dual_c(const int16_t *src_diff, ptrdiff_t src_stride,
+ int16_t *coeff) {
+ for (int i = 0; i < 2; i++) {
+ aom_hadamard_lp_8x8_c(src_diff + (i * 8), src_stride,
+ (int16_t *)coeff + (i * 64));
+ }
+}
+
+// In place 16x16 2D Hadamard transform
+void aom_hadamard_16x16_c(const int16_t *src_diff, ptrdiff_t src_stride,
+ tran_low_t *coeff) {
+ int idx;
+ for (idx = 0; idx < 4; ++idx) {
+ // src_diff: 9 bit, dynamic range [-255, 255]
+ const int16_t *src_ptr =
+ src_diff + (idx >> 1) * 8 * src_stride + (idx & 0x01) * 8;
+ aom_hadamard_8x8_c(src_ptr, src_stride, coeff + idx * 64);
+ }
+
+ // coeff: 15 bit, dynamic range [-16320, 16320]
+ for (idx = 0; idx < 64; ++idx) {
+ tran_low_t a0 = coeff[0];
+ tran_low_t a1 = coeff[64];
+ tran_low_t a2 = coeff[128];
+ tran_low_t a3 = coeff[192];
+
+ tran_low_t b0 = (a0 + a1) >> 1; // (a0 + a1): 16 bit, [-32640, 32640]
+ tran_low_t b1 = (a0 - a1) >> 1; // b0-b3: 15 bit, dynamic range
+ tran_low_t b2 = (a2 + a3) >> 1; // [-16320, 16320]
+ tran_low_t b3 = (a2 - a3) >> 1;
+
+ coeff[0] = b0 + b2; // 16 bit, [-32640, 32640]
+ coeff[64] = b1 + b3;
+ coeff[128] = b0 - b2;
+ coeff[192] = b1 - b3;
+
+ ++coeff;
+ }
+
+ coeff -= 64;
+ // Extra shift to match AVX2 output (i.e., aom_hadamard_16x16_avx2).
+ // Note that to match SSE2 output, it does not need this step.
+ for (int i = 0; i < 16; i++) {
+ for (int j = 0; j < 4; j++) {
+ tran_low_t temp = coeff[i * 16 + 4 + j];
+ coeff[i * 16 + 4 + j] = coeff[i * 16 + 8 + j];
+ coeff[i * 16 + 8 + j] = temp;
+ }
+ }
+}
+
+void aom_hadamard_lp_16x16_c(const int16_t *src_diff, ptrdiff_t src_stride,
+ int16_t *coeff) {
+ for (int idx = 0; idx < 4; ++idx) {
+ // src_diff: 9 bit, dynamic range [-255, 255]
+ const int16_t *src_ptr =
+ src_diff + (idx >> 1) * 8 * src_stride + (idx & 0x01) * 8;
+ aom_hadamard_lp_8x8_c(src_ptr, src_stride, coeff + idx * 64);
+ }
+
+ for (int idx = 0; idx < 64; ++idx) {
+ int16_t a0 = coeff[0];
+ int16_t a1 = coeff[64];
+ int16_t a2 = coeff[128];
+ int16_t a3 = coeff[192];
+
+ int16_t b0 = (a0 + a1) >> 1; // (a0 + a1): 16 bit, [-32640, 32640]
+ int16_t b1 = (a0 - a1) >> 1; // b0-b3: 15 bit, dynamic range
+ int16_t b2 = (a2 + a3) >> 1; // [-16320, 16320]
+ int16_t b3 = (a2 - a3) >> 1;
+
+ coeff[0] = b0 + b2; // 16 bit, [-32640, 32640]
+ coeff[64] = b1 + b3;
+ coeff[128] = b0 - b2;
+ coeff[192] = b1 - b3;
+
+ ++coeff;
+ }
+}
+
+void aom_hadamard_32x32_c(const int16_t *src_diff, ptrdiff_t src_stride,
+ tran_low_t *coeff) {
+ int idx;
+ for (idx = 0; idx < 4; ++idx) {
+ // src_diff: 9 bit, dynamic range [-255, 255]
+ const int16_t *src_ptr =
+ src_diff + (idx >> 1) * 16 * src_stride + (idx & 0x01) * 16;
+ aom_hadamard_16x16_c(src_ptr, src_stride, coeff + idx * 256);
+ }
+
+ // coeff: 16 bit, dynamic range [-32768, 32767]
+ for (idx = 0; idx < 256; ++idx) {
+ tran_low_t a0 = coeff[0];
+ tran_low_t a1 = coeff[256];
+ tran_low_t a2 = coeff[512];
+ tran_low_t a3 = coeff[768];
+
+ tran_low_t b0 = (a0 + a1) >> 2; // (a0 + a1): 17 bit, [-65536, 65535]
+ tran_low_t b1 = (a0 - a1) >> 2; // b0-b3: 15 bit, dynamic range
+ tran_low_t b2 = (a2 + a3) >> 2; // [-16384, 16383]
+ tran_low_t b3 = (a2 - a3) >> 2;
+
+ coeff[0] = b0 + b2; // 16 bit, [-32768, 32767]
+ coeff[256] = b1 + b3;
+ coeff[512] = b0 - b2;
+ coeff[768] = b1 - b3;
+
+ ++coeff;
+ }
+}
+
+#if CONFIG_AV1_HIGHBITDEPTH
+static void hadamard_highbd_col8_first_pass(const int16_t *src_diff,
+ ptrdiff_t src_stride,
+ int16_t *coeff) {
+ int16_t b0 = src_diff[0 * src_stride] + src_diff[1 * src_stride];
+ int16_t b1 = src_diff[0 * src_stride] - src_diff[1 * src_stride];
+ int16_t b2 = src_diff[2 * src_stride] + src_diff[3 * src_stride];
+ int16_t b3 = src_diff[2 * src_stride] - src_diff[3 * src_stride];
+ int16_t b4 = src_diff[4 * src_stride] + src_diff[5 * src_stride];
+ int16_t b5 = src_diff[4 * src_stride] - src_diff[5 * src_stride];
+ int16_t b6 = src_diff[6 * src_stride] + src_diff[7 * src_stride];
+ int16_t b7 = src_diff[6 * src_stride] - src_diff[7 * src_stride];
+
+ int16_t c0 = b0 + b2;
+ int16_t c1 = b1 + b3;
+ int16_t c2 = b0 - b2;
+ int16_t c3 = b1 - b3;
+ int16_t c4 = b4 + b6;
+ int16_t c5 = b5 + b7;
+ int16_t c6 = b4 - b6;
+ int16_t c7 = b5 - b7;
+
+ coeff[0] = c0 + c4;
+ coeff[7] = c1 + c5;
+ coeff[3] = c2 + c6;
+ coeff[4] = c3 + c7;
+ coeff[2] = c0 - c4;
+ coeff[6] = c1 - c5;
+ coeff[1] = c2 - c6;
+ coeff[5] = c3 - c7;
+}
+
+// src_diff: 16 bit, dynamic range [-32760, 32760]
+// coeff: 19 bit
+static void hadamard_highbd_col8_second_pass(const int16_t *src_diff,
+ ptrdiff_t src_stride,
+ int32_t *coeff) {
+ int32_t b0 = src_diff[0 * src_stride] + src_diff[1 * src_stride];
+ int32_t b1 = src_diff[0 * src_stride] - src_diff[1 * src_stride];
+ int32_t b2 = src_diff[2 * src_stride] + src_diff[3 * src_stride];
+ int32_t b3 = src_diff[2 * src_stride] - src_diff[3 * src_stride];
+ int32_t b4 = src_diff[4 * src_stride] + src_diff[5 * src_stride];
+ int32_t b5 = src_diff[4 * src_stride] - src_diff[5 * src_stride];
+ int32_t b6 = src_diff[6 * src_stride] + src_diff[7 * src_stride];
+ int32_t b7 = src_diff[6 * src_stride] - src_diff[7 * src_stride];
+
+ int32_t c0 = b0 + b2;
+ int32_t c1 = b1 + b3;
+ int32_t c2 = b0 - b2;
+ int32_t c3 = b1 - b3;
+ int32_t c4 = b4 + b6;
+ int32_t c5 = b5 + b7;
+ int32_t c6 = b4 - b6;
+ int32_t c7 = b5 - b7;
+
+ coeff[0] = c0 + c4;
+ coeff[7] = c1 + c5;
+ coeff[3] = c2 + c6;
+ coeff[4] = c3 + c7;
+ coeff[2] = c0 - c4;
+ coeff[6] = c1 - c5;
+ coeff[1] = c2 - c6;
+ coeff[5] = c3 - c7;
+}
+
+// The order of the output coeff of the hadamard is not important. For
+// optimization purposes the final transpose may be skipped.
+void aom_highbd_hadamard_8x8_c(const int16_t *src_diff, ptrdiff_t src_stride,
+ tran_low_t *coeff) {
+ int idx;
+ int16_t buffer[64];
+ int32_t buffer2[64];
+ int16_t *tmp_buf = &buffer[0];
+ for (idx = 0; idx < 8; ++idx) {
+ // src_diff: 13 bit
+ // buffer: 16 bit, dynamic range [-32760, 32760]
+ hadamard_highbd_col8_first_pass(src_diff, src_stride, tmp_buf);
+ tmp_buf += 8;
+ ++src_diff;
+ }
+
+ tmp_buf = &buffer[0];
+ for (idx = 0; idx < 8; ++idx) {
+ // buffer: 16 bit
+ // buffer2: 19 bit, dynamic range [-262080, 262080]
+ hadamard_highbd_col8_second_pass(tmp_buf, 8, buffer2 + 8 * idx);
+ ++tmp_buf;
+ }
+
+ for (idx = 0; idx < 64; ++idx) coeff[idx] = (tran_low_t)buffer2[idx];
+}
+
+// In place 16x16 2D Hadamard transform
+void aom_highbd_hadamard_16x16_c(const int16_t *src_diff, ptrdiff_t src_stride,
+ tran_low_t *coeff) {
+ int idx;
+ for (idx = 0; idx < 4; ++idx) {
+ // src_diff: 13 bit, dynamic range [-4095, 4095]
+ const int16_t *src_ptr =
+ src_diff + (idx >> 1) * 8 * src_stride + (idx & 0x01) * 8;
+ aom_highbd_hadamard_8x8_c(src_ptr, src_stride, coeff + idx * 64);
+ }
+
+ // coeff: 19 bit, dynamic range [-262080, 262080]
+ for (idx = 0; idx < 64; ++idx) {
+ tran_low_t a0 = coeff[0];
+ tran_low_t a1 = coeff[64];
+ tran_low_t a2 = coeff[128];
+ tran_low_t a3 = coeff[192];
+
+ tran_low_t b0 = (a0 + a1) >> 1;
+ tran_low_t b1 = (a0 - a1) >> 1;
+ tran_low_t b2 = (a2 + a3) >> 1;
+ tran_low_t b3 = (a2 - a3) >> 1;
+
+ // new coeff dynamic range: 20 bit
+ coeff[0] = b0 + b2;
+ coeff[64] = b1 + b3;
+ coeff[128] = b0 - b2;
+ coeff[192] = b1 - b3;
+
+ ++coeff;
+ }
+}
+
+void aom_highbd_hadamard_32x32_c(const int16_t *src_diff, ptrdiff_t src_stride,
+ tran_low_t *coeff) {
+ int idx;
+ for (idx = 0; idx < 4; ++idx) {
+ // src_diff: 13 bit, dynamic range [-4095, 4095]
+ const int16_t *src_ptr =
+ src_diff + (idx >> 1) * 16 * src_stride + (idx & 0x01) * 16;
+ aom_highbd_hadamard_16x16_c(src_ptr, src_stride, coeff + idx * 256);
+ }
+
+ // coeff: 20 bit
+ for (idx = 0; idx < 256; ++idx) {
+ tran_low_t a0 = coeff[0];
+ tran_low_t a1 = coeff[256];
+ tran_low_t a2 = coeff[512];
+ tran_low_t a3 = coeff[768];
+
+ tran_low_t b0 = (a0 + a1) >> 2;
+ tran_low_t b1 = (a0 - a1) >> 2;
+ tran_low_t b2 = (a2 + a3) >> 2;
+ tran_low_t b3 = (a2 - a3) >> 2;
+
+ // new coeff dynamic range: 20 bit
+ coeff[0] = b0 + b2;
+ coeff[256] = b1 + b3;
+ coeff[512] = b0 - b2;
+ coeff[768] = b1 - b3;
+
+ ++coeff;
+ }
+}
+#endif // CONFIG_AV1_HIGHBITDEPTH
+
+// coeff: 20 bits, dynamic range [-524287, 524287].
+// length: value range {16, 32, 64, 128, 256, 512, 1024}.
+int aom_satd_c(const tran_low_t *coeff, int length) {
+ int i;
+ int satd = 0;
+ for (i = 0; i < length; ++i) satd += abs(coeff[i]);
+
+ // satd: 30 bits, dynamic range [-524287 * 1024, 524287 * 1024]
+ return satd;
+}
+
+int aom_satd_lp_c(const int16_t *coeff, int length) {
+ int satd = 0;
+ for (int i = 0; i < length; ++i) satd += abs(coeff[i]);
+
+ // satd: 26 bits, dynamic range [-32640 * 1024, 32640 * 1024]
+ return satd;
+}
+
+// Integer projection onto row vectors.
+// height: value range {16, 32, 64, 128}.
+void aom_int_pro_row_c(int16_t *hbuf, const uint8_t *ref, const int ref_stride,
+ const int width, const int height, int norm_factor) {
+ assert(height >= 2);
+ for (int idx = 0; idx < width; ++idx) {
+ hbuf[idx] = 0;
+ // hbuf[idx]: 14 bit, dynamic range [0, 32640].
+ for (int i = 0; i < height; ++i) hbuf[idx] += ref[i * ref_stride];
+ // hbuf[idx]: 9 bit, dynamic range [0, 1020].
+ hbuf[idx] >>= norm_factor;
+ ++ref;
+ }
+}
+
+// width: value range {16, 32, 64, 128}.
+void aom_int_pro_col_c(int16_t *vbuf, const uint8_t *ref, const int ref_stride,
+ const int width, const int height, int norm_factor) {
+ for (int ht = 0; ht < height; ++ht) {
+ int16_t sum = 0;
+ // sum: 14 bit, dynamic range [0, 32640]
+ for (int idx = 0; idx < width; ++idx) sum += ref[idx];
+ vbuf[ht] = sum >> norm_factor;
+ ref += ref_stride;
+ }
+}
+
+// ref: [0 - 510]
+// src: [0 - 510]
+// bwl: {2, 3, 4, 5}
+int aom_vector_var_c(const int16_t *ref, const int16_t *src, int bwl) {
+ int i;
+ int width = 4 << bwl;
+ int sse = 0, mean = 0, var;
+
+ for (i = 0; i < width; ++i) {
+ int diff = ref[i] - src[i]; // diff: dynamic range [-510, 510], 10 bits.
+ mean += diff; // mean: dynamic range 16 bits.
+ sse += diff * diff; // sse: dynamic range 26 bits.
+ }
+
+ // (mean * mean): dynamic range 31 bits.
+ // If width == 128, the mean can be 510 * 128 = 65280, and log2(65280 ** 2) ~=
+ // 31.99, so it needs to be casted to unsigned int to compute its square.
+ const unsigned int mean_abs = abs(mean);
+ var = sse - ((mean_abs * mean_abs) >> (bwl + 2));
+ return var;
+}