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// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "src/decoder/footprint.h"
#include "src/base/string_utils.h"
#include <map>
#include <string>
#include <utility>
#include <vector>
namespace astc_codec {
namespace {
// Encodes the width and height into an integer so that we can use a switch
// statement instead of a costly lookup map.
constexpr int EncodeDims(int width, int height) {
return (width << 16) | height;
}
} // namespace
base::Optional<FootprintType>
Footprint::GetValidFootprintForDimensions(int width, int height) {
switch (EncodeDims(width, height)) {
case EncodeDims(4, 4): return FootprintType::k4x4;
case EncodeDims(5, 4): return FootprintType::k5x4;
case EncodeDims(5, 5): return FootprintType::k5x5;
case EncodeDims(6, 5): return FootprintType::k6x5;
case EncodeDims(6, 6): return FootprintType::k6x6;
case EncodeDims(8, 5): return FootprintType::k8x5;
case EncodeDims(8, 6): return FootprintType::k8x6;
case EncodeDims(8, 8): return FootprintType::k8x8;
case EncodeDims(10, 5): return FootprintType::k10x5;
case EncodeDims(10, 6): return FootprintType::k10x6;
case EncodeDims(10, 8): return FootprintType::k10x8;
case EncodeDims(10, 10): return FootprintType::k10x10;
case EncodeDims(12, 10): return FootprintType::k12x10;
case EncodeDims(12, 12): return FootprintType::k12x12;
default: return {};
}
}
int Footprint::GetWidthForFootprint(FootprintType footprint) {
switch (footprint) {
case FootprintType::k4x4: return 4;
case FootprintType::k5x4: return 5;
case FootprintType::k5x5: return 5;
case FootprintType::k6x5: return 6;
case FootprintType::k6x6: return 6;
case FootprintType::k8x5: return 8;
case FootprintType::k8x6: return 8;
case FootprintType::k10x5: return 10;
case FootprintType::k10x6: return 10;
case FootprintType::k8x8: return 8;
case FootprintType::k10x8: return 10;
case FootprintType::k10x10: return 10;
case FootprintType::k12x10: return 12;
case FootprintType::k12x12: return 12;
default:
assert(false);
return -1;
}
}
int Footprint::GetHeightForFootprint(FootprintType footprint) {
switch (footprint) {
case FootprintType::k4x4: return 4;
case FootprintType::k5x4: return 4;
case FootprintType::k5x5: return 5;
case FootprintType::k6x5: return 5;
case FootprintType::k6x6: return 6;
case FootprintType::k8x5: return 5;
case FootprintType::k8x6: return 6;
case FootprintType::k10x5: return 5;
case FootprintType::k10x6: return 6;
case FootprintType::k8x8: return 8;
case FootprintType::k10x8: return 8;
case FootprintType::k10x10: return 10;
case FootprintType::k12x10: return 10;
case FootprintType::k12x12: return 12;
default:
assert(false);
return -1;
}
}
Footprint::Footprint(FootprintType footprint)
: footprint_(footprint), width_(GetWidthForFootprint(footprint)),
height_(GetHeightForFootprint(footprint)) { }
////////////////////////////////////////////////////////////////////////////////
base::Optional<Footprint> Footprint::Parse(const char* footprint_string) {
assert(footprint_string && footprint_string[0] != '\0');
std::vector<std::string> dimension_strings;
base::Split(footprint_string, "x", [&dimension_strings](std::string&& s) {
dimension_strings.push_back(std::move(s));
});
if (dimension_strings.size() != 2) {
assert(false && "Invalid format for footprint");
return {};
}
const int width = base::ParseInt32(dimension_strings[0].c_str(), 0);
const int height = base::ParseInt32(dimension_strings[1].c_str(), 0);
assert(width > 0 && height > 0 && "Invalid width or height.");
return FromDimensions(width, height);
}
base::Optional<Footprint> Footprint::FromDimensions(int width, int height) {
base::Optional<FootprintType> valid_footprint =
GetValidFootprintForDimensions(width, height);
if (valid_footprint) {
return Footprint(valid_footprint.value());
} else {
return {};
}
}
// Returns a Footprint for the given FootprintType.
base::Optional<Footprint> Footprint::FromFootprintType(FootprintType type) {
if (type >= FootprintType::k4x4 && type < FootprintType::kCount) {
return Footprint(type);
} else {
return {};
}
}
size_t Footprint::StorageRequirements(int width, int height) const {
const int blocks_wide = (width + width_ - 1) / width_;
const int blocks_high = (height + height_ - 1) / height_;
constexpr size_t kASTCBlockSizeInBytes = 16;
return blocks_wide * blocks_high * kASTCBlockSizeInBytes;
}
// Returns bits/pixel for a given footprint.
float Footprint::Bitrate() const {
const int kASTCBlockBitCount = 128;
const int footprint_pixel_count = width_ * height_;
return static_cast<float>(kASTCBlockBitCount) /
static_cast<float>(footprint_pixel_count);
}
} // namespace astc_codec
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