system/dev/input/hid/hid-parser-lib.cpp

// Copyright 2018 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 "hid-parser.h"

#include <hid-parser/item.h>
#include <hid-parser/parser.h>
#include <hid-parser/usages.h>

#include <stdlib.h>
#include <string.h>

zx_status_t hid_lib_parse_reports(const uint8_t* buf, const size_t buf_len,
                                  hid_reports_t* reports) {

    hid::DeviceDescriptor* desc = nullptr;
    auto res = hid::ParseReportDescriptor(buf, buf_len, &desc);

    if (res != hid::ParseResult::kParseOk) {
        return -1;
    }

    for (size_t item = 0; item < desc->rep_count; item++) {
        hid::ReportDescriptor* desc_rep = &desc->report[item];
        hid_report_size_t* hiddev_rep = &reports->sizes[item];
        hiddev_rep->id = desc_rep->report_id;
        if (hiddev_rep->id != 0) {
            reports->has_rpt_id = true;
        }
        reports->num_reports++;

        for (size_t i = 0; i < desc_rep->count; i++) {
            hid::ReportField* field = desc_rep->first_field + i;
            input_report_size_t size = field->attr.bit_sz;
            switch (field->type) {
            case hid::kInput:
                hiddev_rep->in_size = static_cast<input_report_size_t>(hiddev_rep->in_size + size);
                break;
            case hid::kOutput:
                hiddev_rep->out_size = static_cast<input_report_size_t>(hiddev_rep->out_size
                                                                        + size);
                break;
            case hid::kFeature:
                hiddev_rep->feat_size = static_cast<input_report_size_t>(hiddev_rep->feat_size
                                                                         + size);
                break;
            }
        }
    }

    FreeDeviceDescriptor(desc);
    return ZX_OK;
}