system/hwc3/EdidInfo.cpp

#include "EdidInfo.h"

#include "Common.h"

namespace aidl::android::hardware::graphics::composer3::impl {
std::optional<EdidInfo> EdidInfo::parse(std::span<const uint8_t> blob) {
    constexpr size_t kEdidDescriptorOffset = 54;
    constexpr size_t kEdidDescriptorLength = 18;

    blob = blob.subspan(kEdidDescriptorOffset);

    using byte_view = std::span<const uint8_t>;
    byte_view descriptor(blob.data(), kEdidDescriptorLength);
    if (descriptor[0] == 0 && descriptor[1] == 0) {
        ALOGE("%s: missing preferred detailed timing descriptor", __FUNCTION__);
        return std::nullopt;
    }

    const uint8_t w_mm_lsb = descriptor[12];
    const uint8_t h_mm_lsb = descriptor[13];
    const uint8_t w_and_h_mm_msb = descriptor[14];

    return EdidInfo{
        .mWidthMillimeters =
            static_cast<uint32_t>(w_mm_lsb) | ((static_cast<uint32_t>(w_and_h_mm_msb) & 0xf0) << 4),
        .mHeightMillimeters =
            static_cast<uint32_t>(h_mm_lsb) | ((static_cast<uint32_t>(w_and_h_mm_msb) & 0xf) << 8),
    };
}
}  // namespace aidl::android::hardware::graphics::composer3::impl