src/ui/input/bin/hid/report.cc

// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <stdio.h>

#include <hid-parser/item.h>

namespace {

const char* TypeName(hid::Item::Type t) {
  switch (t) {
#define TYPE(t)               \
  case hid::Item::Type::k##t: \
    return #t
    TYPE(Main);
    TYPE(Global);
    TYPE(Local);
    TYPE(Reserved);
#undef TYPE
    default:
      return "(unknown)";
  }
}

const char* TagName(hid::Item::Tag t) {
  switch (t) {
#define TAG(t)               \
  case hid::Item::Tag::k##t: \
    return #t
    TAG(Input);
    TAG(Output);
    TAG(Feature);
    TAG(Collection);
    TAG(EndCollection);
    TAG(UsagePage);
    TAG(LogicalMinimum);
    TAG(LogicalMaximum);
    TAG(PhysicalMinimum);
    TAG(PhysicalMaximum);
    TAG(UnitExponent);
    TAG(Unit);
    TAG(ReportSize);
    TAG(ReportId);
    TAG(ReportCount);
    TAG(Push);
    TAG(Pop);
    TAG(Usage);
    TAG(UsageMinimum);
    TAG(UsageMaximum);
    TAG(DesignatorIndex);
    TAG(DesignatorMinimum);
    TAG(DesignatorMaximum);
    TAG(StringIndex);
    TAG(StringMinimum);
    TAG(StringMaximum);
    TAG(Delimiter);
    TAG(Reserved);
#undef TAG
    default:
      return "(unknown)";
  }
}
}  // namespace

void print_report_descriptor(const uint8_t* rpt_desc, size_t desc_len) {
  const uint8_t* buf = rpt_desc;
  size_t len = desc_len;
  int indent = 0;
  const int kIndentChars = 4;

  while (len > 0) {
    size_t item_actual = 0;
    auto item = hid::Item::ReadNext(buf, len, &item_actual);

    if (item_actual > len) {
      printf("%zu bytes needed for item\n", item_actual);
      break;
    }

    if (item_actual == 0) {
      printf("Error parsing report stream.\n");
      break;
    }

    if (item.tag() == hid::Item::Tag::kEndCollection) {
      if (indent < kIndentChars) {
        printf("unmatched ==> ");
      } else {
        indent -= kIndentChars;
      }
    }

    printf("%*s Item(%s, %s): %0#x\n", indent, "", TypeName(item.type()), TagName(item.tag()),
           item.data());

    if (item.tag() == hid::Item::Tag::kCollection) {
      indent += kIndentChars;
    }

    len -= item_actual;
    buf += item_actual;
  }

  if (len > 0) {
    printf("%zu bytes not consumed.\n", len);
  }
}