Added unit test for subtract functions

Patch Set 1: gain familiarity with unit tests... added simple
4x4 subtract test
Patch Set 2: fixed mistakes, parameterized as suggested
Patch Set 3: randomized the source/predictor data


Change-Id: I33432bdf7c9f2a9b8c2533a37106382c2a8209ee
Signed-off-by: Scott LaVarnway <slavarnway@google.com>

test/subtract_test.cc

+/*
+ *  Copyright (c) 2012 The WebM project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "third_party/googletest/src/include/gtest/gtest.h"
+#include "test/acm_random.h"
+extern "C" {
+#include "vpx_config.h"
+#include "vpx_rtcd.h"
+#include "vp8/common/blockd.h"
+#include "vp8/encoder/block.h"
+#include "vpx_mem/vpx_mem.h"
+}
+
+typedef void (*subtract_b_fn_t)(BLOCK *be, BLOCKD *bd, int pitch);
+
+namespace {
+
+class SubtractBlockTest : public ::testing::TestWithParam<subtract_b_fn_t> {};
+
+using libvpx_test::ACMRandom;
+
+TEST_P(SubtractBlockTest, SimpleSubtract) {
+  ACMRandom rnd(ACMRandom::DeterministicSeed());
+  BLOCK be;
+  BLOCKD bd;
+  // in libvpx, this stride is always 16
+  const int kDiffPredStride = 16;
+  const int kSrcStride[] = {32, 16, 8, 4, 0};
+  const int kBlockWidth = 4;
+  const int kBlockHeight = 4;
+
+  // Allocate... align to 16 for mmx/sse tests
+  uint8_t *source = reinterpret_cast<uint8_t*>(
+      vpx_memalign(16, kBlockHeight * kSrcStride[0] * sizeof(*source)));
+  be.src_diff = reinterpret_cast<int16_t*>(
+      vpx_memalign(16, kBlockHeight * kDiffPredStride * sizeof(*be.src_diff)));
+  bd.predictor = reinterpret_cast<unsigned char*>(
+      vpx_memalign(16, kBlockHeight * kDiffPredStride * sizeof(*bd.predictor)));
+
+  for(int i = 0; kSrcStride[i] > 0; ++i) {
+    // start at block0
+    be.src = 0;
+    be.base_src = &source;
+    be.src_stride = kSrcStride[i];
+
+    // set difference
+    int16_t *src_diff = be.src_diff;
+    for (int r = 0; r < kBlockHeight; ++r) {
+      for (int c = 0; c < kBlockWidth; ++c) {
+        src_diff[c] = 0xa5a5;
+      }
+      src_diff += kDiffPredStride;
+    }
+
+    // set destination
+    uint8_t *base_src = *be.base_src;
+    for (int r = 0; r < kBlockHeight; ++r) {
+      for (int c = 0; c < kBlockWidth; ++c) {
+        base_src[c] = rnd.Rand8();
+      }
+      base_src += be.src_stride;
+    }
+
+    // set predictor
+    uint8_t *predictor = bd.predictor;
+    for (int r = 0; r < kBlockHeight; ++r) {
+      for (int c = 0; c < kBlockWidth; ++c) {
+        predictor[c] = rnd.Rand8();
+      }
+      predictor += kDiffPredStride;
+    }
+
+    GetParam()(&be, &bd, kDiffPredStride);
+
+    base_src = *be.base_src;
+    src_diff = be.src_diff;
+    predictor = bd.predictor;
+    for (int r = 0; r < kBlockHeight; ++r) {
+      for (int c = 0; c < kBlockWidth; ++c) {
+        EXPECT_EQ(base_src[c], (src_diff[c] + predictor[c])) << "r = " << r
+                                                             << ", c = " << c;
+      }
+      src_diff += kDiffPredStride;
+      predictor += kDiffPredStride;
+      base_src += be.src_stride;
+    }
+  }
+  vpx_free(be.src_diff);
+  vpx_free(source);
+  vpx_free(bd.predictor);
+}
+
+INSTANTIATE_TEST_CASE_P(C, SubtractBlockTest,
+                        ::testing::Values(vp8_subtract_b_c));
+
+#if HAVE_MMX
+INSTANTIATE_TEST_CASE_P(MMX, SubtractBlockTest,
+                        ::testing::Values(vp8_subtract_b_mmx));
+#endif
+
+#if HAVE_SSE2
+INSTANTIATE_TEST_CASE_P(SSE2, SubtractBlockTest,
+                        ::testing::Values(vp8_subtract_b_sse2));
+#endif
+
+}  // namespace

test/test.mk

@@ -39,6 +39,7 @@ LIBVPX_TEST_SRCS-$(CONFIG_POSTPROC)    += pp_filter_test.cc
 LIBVPX_TEST_SRCS-yes                   += sad_test.cc
 LIBVPX_TEST_SRCS-$(CONFIG_VP8_ENCODER) += set_roi.cc
 LIBVPX_TEST_SRCS-yes                   += sixtap_predict_test.cc
+LIBVPX_TEST_SRCS-$(CONFIG_VP8_ENCODER) += subtract_test.cc
 
 endif